effect of comparison in literature

What is a Comparison?

Comparison definition.

A comparison is a consideration of the similarities or differences between two things. Comparisons can be made between people, places, ideas, or other entities. Making a comparison can highlight how two things are alike or unalike, creating meaningful and/or innovative perspectives for the reader.

Use of Comparison in Literature

Writers use comparisons for description and imagery to enhance a reader’s understanding and/or enjoyment of the material. Many literary devices utilize this form of figurative language , such as:

Poetry is often constructed by using comparison, such as “She walks in beauty , like the night .”

Examples of Comparison in Literature

In the following comparison examples, we will try to analyze literary devices used to show comparisons.

A metaphor makes a hidden comparison between two things or objects that are dissimilar to each other, but have some characteristics common between them. Unlike simile , we do not use “like” or “as” to develop a comparison in a metaphor. Consider the following examples:

Example #1: When I Have Fears (By John Keats)

These lines are from When I Have Fears , by John Keats .

“Before high-pil’d books, in charact’ry Hold like rich garners the full-ripened grain,”

John Keats compares writing poetry with reaping and sowing, and both these acts stand for the insignificance of a life and dissatisfied creativity.

Example #2: As You Like It (By William Shakespeare)

This line is from As You Like It , by William Shakespeare .

“All the world’s a stage and men and women merely players…”

Shakespeare uses a metaphor of a stage to describe the world, and compares men and women living in the world with players (actors).

A simile is an open comparison between two things or objects to show similarities between them. Unlike a metaphor, a simile draws resemblance with the help of words “like” or “as.”

Example #3: Lolita (By Vladimir Nabokov)

This line is from the short story Lolita , by Vladimir Nabokov.

“Elderly American ladies leaning on their canes listed toward me like towers of Pisa.”

In this line, Vladimir Nabokov compares old women leaning on their sticks to the Leaning Tower of Pisa. Here the comparison made between two contrasting things creates a hilarious effect.

An analogy aims at explaining an unfamiliar idea or thing, by comparing it to something that is familiar.

Example #4: The Noiseless Patient Spider (By Walt Whitman)

These lines are from Walt Whitman ’s poem The Noiseless Patient Spider “:

“And you O my soul where you stand, Surrounded, detached, in measureless oceans of space, Ceaselessly musing, venturing, throwing, seeking the spheres to connect them, Till the bridge you will need be form’d, till the ductile anchor hold, Till the gossamer thread you fling catch somewhere, O my soul.”

Walt Whitman uses an analogy to show similarity between a spider spinning a web and his soul.

Example #5: Night Clouds (By Amy Lowell)

These lines are from Night Clouds , written by Amy Lowell:

“The white mares of the moon rush along the sky Beating their golden hoofs upon the glass Heavens.”

Amy constructs an analogy between clouds and mares. She compares the movement of the white clouds in the sky at night with the movement of white mares on the ground.

An allegory uses symbols to compare persons or things, to represent abstract ideas or events. The comparison in allegory is implicit.

Example #6: Animal Farm (By George Orwell)

Animal Farm , written by George Orwell , is an allegory that compares animals on a farm to the Communist Revolution in Russia before WW II. The actions of the animals on the farm can be compared with the greed and corruption after the revolution. The animals on the farm represent different sections of Russian society after the revolution.

For instance, “Pigs” can be compared to those who became the authority after the revolution;”Mr. Jones,” the owner of the farm, is likened to the overthrown Tsar Nicholas II; and “Boxer,” the horse, stands for the laborer class.

Example #7: Faerie Queen (By Edmund Spenser)

Faerie Queen is an allegory by Edmund Spenser, in which the good characters of the book can be compared to the various virtues , while the bad characters can be compared to vices. For example, “The Red- Cross Knight” represents Holiness, and “Lady Una” Truth, Wisdom, and Goodness. Her parents symbolize the Human Race, and the “Dragon,” which has imprisoned them, stands for Evil.

Function of Comparison

The above examples of comparison help us realize that, in general, writers utilize different kinds of comparison to link an unfamiliar or a new idea to common and familiar objects. It helps readers to comprehend a new idea, which may have been difficult for them to understand otherwise. The understanding of a new idea turns out to be simpler when viewed with a comparison to something that is familiar to them.

In addition, by making use of various literary tools for comparison, writers increase their chances of catching the attention and interest of their readers, as comparisons help them identify what they are reading to their lives.

Comparison and Contrast Essay

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Comparing and contrasting in an essay | Tips & examples

Comparing and Contrasting in an Essay | Tips & Examples

Published on August 6, 2020 by Jack Caulfield . Revised on July 23, 2023.

Comparing and contrasting is an important skill in academic writing . It involves taking two or more subjects and analyzing the differences and similarities between them.

When should i compare and contrast, making effective comparisons, comparing and contrasting as a brainstorming tool, structuring your comparisons, other interesting articles, frequently asked questions about comparing and contrasting.

Many assignments will invite you to make comparisons quite explicitly, as in these prompts.

Compare the treatment of the theme of beauty in the poetry of William Wordsworth and John Keats.
Compare and contrast in-class and distance learning. What are the advantages and disadvantages of each approach?

Some other prompts may not directly ask you to compare and contrast, but present you with a topic where comparing and contrasting could be a good approach.

One way to approach this essay might be to contrast the situation before the Great Depression with the situation during it, to highlight how large a difference it made.

Comparing and contrasting is also used in all kinds of academic contexts where it’s not explicitly prompted. For example, a literature review involves comparing and contrasting different studies on your topic, and an argumentative essay may involve weighing up the pros and cons of different arguments.

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As the name suggests, comparing and contrasting is about identifying both similarities and differences. You might focus on contrasting quite different subjects or comparing subjects with a lot in common—but there must be some grounds for comparison in the first place.

For example, you might contrast French society before and after the French Revolution; you’d likely find many differences, but there would be a valid basis for comparison. However, if you contrasted pre-revolutionary France with Han-dynasty China, your reader might wonder why you chose to compare these two societies.

This is why it’s important to clarify the point of your comparisons by writing a focused thesis statement . Every element of an essay should serve your central argument in some way. Consider what you’re trying to accomplish with any comparisons you make, and be sure to make this clear to the reader.

Comparing and contrasting can be a useful tool to help organize your thoughts before you begin writing any type of academic text. You might use it to compare different theories and approaches you’ve encountered in your preliminary research, for example.

Let’s say your research involves the competing psychological approaches of behaviorism and cognitive psychology. You might make a table to summarize the key differences between them.

Or say you’re writing about the major global conflicts of the twentieth century. You might visualize the key similarities and differences in a Venn diagram.

A Venn diagram showing the similarities and differences between World War I, World War II, and the Cold War.

These visualizations wouldn’t make it into your actual writing, so they don’t have to be very formal in terms of phrasing or presentation. The point of comparing and contrasting at this stage is to help you organize and shape your ideas to aid you in structuring your arguments.

When comparing and contrasting in an essay, there are two main ways to structure your comparisons: the alternating method and the block method.

The alternating method

In the alternating method, you structure your text according to what aspect you’re comparing. You cover both your subjects side by side in terms of a specific point of comparison. Your text is structured like this:

Mouse over the example paragraph below to see how this approach works.

One challenge teachers face is identifying and assisting students who are struggling without disrupting the rest of the class. In a traditional classroom environment, the teacher can easily identify when a student is struggling based on their demeanor in class or simply by regularly checking on students during exercises. They can then offer assistance quietly during the exercise or discuss it further after class. Meanwhile, in a Zoom-based class, the lack of physical presence makes it more difficult to pay attention to individual students’ responses and notice frustrations, and there is less flexibility to speak with students privately to offer assistance. In this case, therefore, the traditional classroom environment holds the advantage, although it appears likely that aiding students in a virtual classroom environment will become easier as the technology, and teachers’ familiarity with it, improves.

The block method

In the block method, you cover each of the overall subjects you’re comparing in a block. You say everything you have to say about your first subject, then discuss your second subject, making comparisons and contrasts back to the things you’ve already said about the first. Your text is structured like this:

Point of comparison A
Point of comparison B

The most commonly cited advantage of distance learning is the flexibility and accessibility it offers. Rather than being required to travel to a specific location every week (and to live near enough to feasibly do so), students can participate from anywhere with an internet connection. This allows not only for a wider geographical spread of students but for the possibility of studying while travelling. However, distance learning presents its own accessibility challenges; not all students have a stable internet connection and a computer or other device with which to participate in online classes, and less technologically literate students and teachers may struggle with the technical aspects of class participation. Furthermore, discomfort and distractions can hinder an individual student’s ability to engage with the class from home, creating divergent learning experiences for different students. Distance learning, then, seems to improve accessibility in some ways while representing a step backwards in others.

Note that these two methods can be combined; these two example paragraphs could both be part of the same essay, but it’s wise to use an essay outline to plan out which approach you’re taking in each paragraph.

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Some essay prompts include the keywords “compare” and/or “contrast.” In these cases, an essay structured around comparing and contrasting is the appropriate response.

Comparing and contrasting is also a useful approach in all kinds of academic writing : You might compare different studies in a literature review , weigh up different arguments in an argumentative essay , or consider different theoretical approaches in a theoretical framework .

Your subjects might be very different or quite similar, but it’s important that there be meaningful grounds for comparison . You can probably describe many differences between a cat and a bicycle, but there isn’t really any connection between them to justify the comparison.

You’ll have to write a thesis statement explaining the central point you want to make in your essay , so be sure to know in advance what connects your subjects and makes them worth comparing.

Comparisons in essays are generally structured in one of two ways:

The alternating method, where you compare your subjects side by side according to one specific aspect at a time.
The block method, where you cover each subject separately in its entirety.

It’s also possible to combine both methods, for example by writing a full paragraph on each of your topics and then a final paragraph contrasting the two according to a specific metric.

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Comparison Definition

Comparison is a rhetorical or literary device in which a writer compares or contrasts two people, places, things, or ideas. In our everyday life, we compare people and things to express ourselves vividly. So when we say, someone is “as lazy as a snail,” you compare two different entities to show similarity i.e. someone’s laziness to the slow pace of a snail.

Comparisons occur in literary works frequently. Writers and poets use comparison in order to link their feelings about a thing to something readers can understand. There are numerous devices in literature that compare two different things to show the similarity between them, such as simile , metaphor , and analogy .

Examples of Comparison in Literature

In the following comparison examples, we will try to analyze literary devices used to show comparisons.

Example #1: When I Have Fears (By John Keats)

These lines are from When I Have Fears , by John Keats.

“Before high-pil’d books, in charact’ry Hold like rich garners the full-ripened grain,”

John Keats compares writing poetry with reaping and sowing, and both these acts stand for the insignificance of a life and dissatisfied creativity.

Example #2: As You Like It (By William Shakespeare)

This line is from As You Like It , by William Shakespeare.

“All the world’s a stage and men and women merely players…”

Shakespeare uses a metaphor of a stage to describe the world, and compares men and women living in the world with players (actors).

A simile is an open comparison between two things or objects to show similarities between them. Unlike a metaphor , a simile draws resemblance with the help of words “like” or “as.”

Example #3: Lolita (By Vladimir Nabokov)

This line is from the short story Lolita , by Vladimir Nabokov.

“Elderly American ladies leaning on their canes listed toward me like towers of Pisa.”

In this line, Vladimir Nabokov compares old women leaning on their sticks to the Leaning Tower of Pisa. Here the comparison made between two contrasting things creates a hilarious effect.

An analogy aims at explaining an unfamiliar idea or thing, by comparing it to something that is familiar.

Example #4: The Noiseless Patient Spider (By Walt Whitman)

These lines are from Walt Whitman’s poem The Noiseless Patient Spider “:

“And you O my soul where you stand, Surrounded, detached, in measureless oceans of space, Ceaselessly musing, venturing, throwing, seeking the spheres to connect them, Till the bridge you will need be form’d, till the ductile anchor hold, Till the gossamer thread you fling catch somewhere, O my soul.”

Walt Whitman uses an analogy to show similarity between a spider spinning a web and his soul.

Example #5: Night Clouds (By Amy Lowell)

These lines are from Night Clouds , written by Amy Lowell:

“The white mares of the moon rush along the sky Beating their golden hoofs upon the glass Heavens.”

Amy constructs an analogy between clouds and mares. She compares the movement of the white clouds in the sky at night with the movement of white mares on the ground.

An allegory uses symbols to compare persons or things, to represent abstract ideas or events. The comparison in allegory is implicit.

Example #6: Animal Farm (By George Orwell)

Animal Farm , written by George Orwell, is an allegory that compares animals on a farm to the Communist Revolution in Russia before WW II. The actions of the animals on the farm can be compared with the greed and corruption after the revolution. The animals on the farm represent different sections of Russian society after the revolution.

Example #7: Faerie Queen (By Edmund Spenser)

Faerie Queen is an allegory by Edmund Spenser, in which the good characters of the book can be compared to the various virtues, while the bad characters can be compared to vices. For example, “The Red-Cross Knight” represents Holiness, and “Lady Una” Truth, Wisdom, and Goodness. Her parents symbolize the Human Race, and the “Dragon,” which has imprisoned them, stands for Evil.

Function of Comparison

Literary Devices

Literary devices, terms, and elements, definition of comparison.

As a literary device, comparison is a broad term for any act of describing the relationship between two things or more things. These things (whether people, actions, intangible concepts, places, etc) may be alike or different to any degree. Through comparison, an author may show new connections that the reader may not have thought of, or may make an unfamiliar thing more familiar. There are many more specific types of comparison, as we will see below.

The word comparison comes from the Latin word comparare , which means “to pair, match.”

Types of Comparisons

Analogy —Another umbrella term, similar to the definition of comparison, referring to any comparison that explores the similarities or differences between two things.
Juxtaposition —Placing two concepts, characters, ideas, etc., near each other so that the reader makes comparisons between them and perhaps contrasts them as well.
Metaphor —Comparing two things without the use of “like” or “as;” asserting that one thing is another, such as “My love is an ocean.”
Simile —Comparing two things with the conjunction “like” or “as,” such as “My love was like an ocean.”
Pun —Using comparison to creative cognitive links in a humorous way, for example, “I’m glad I know sign language, it’s pretty handy.”
Allegory —An extended metaphor that carries throughout an entire piece of literature that compares the situation in the story to a real-life situation.

Common Examples of Comparison

We use comparisons all the time in the real world and in everyday speech. Comparisons help us understand the world around us because we can either explain unfamiliar things through already known entities, or complicate familiar things by describing them in new ways that thus creates cognitive links. Examples of comparison abound, and are found in each of the following cases:

“Have you met my friend Janet? She’s exactly like your sister, except more dramatic.”
“This new young adult novel is like Harry Potter meets Titanic.”
“Come on now, quick as a bunny.”
“The little red dress is the new little black dress this season when it comes to Hollywood glamour.”
“Wearing white after Labor Day would be a sin of epic proportions.”

Significance of Comparison in Literature

Comparisons play an important role in just about any work of literature imaginable, as they are a primary function of the brain. It is through comparisons that we learn and map out the world. Even the simple act of naming things requires comparison in the brain—we refer, for example, to many different-looking objects as “chair” because we can compare them in our minds and realize they all have the same general function. Comparisons are especially important in literature because authors are creating a new world for the reader to understand and become interested in, and authors must show how this new, fictive world is similar and dissimilar from the one the reader lives in (even if the work of literature is completely realistic). Writers also may use comparisons to make their lines more poetic.

Examples of Comparison in Literature

Shall I compare thee to a summer’s day? Thou art more lovely and more temperate. Rough winds do shake the darling buds of May, And summer’s lease hath all too short a date. Sometime too hot the eye of heaven shines, And often is his gold complexion dimmed; And every fair from fair sometime declines, By chance, or nature’s changing course, untrimmed; But thy eternal summer shall not fade,

(“ Sonnet 18” by William Shakespeare)

William Shakespeare’s “Sonnet 18” includes one of the famous examples of comparison in literature. The speaker asks explicitly if he should compare his beloved to “a summer’s day,” and goes on to do so. He finds the summer’s day inadequate as a comparison for his beloved, insisting that “thou art more lovely and more temperate.” This comparison works to show the speaker’s all-encompassing love.

Something there is that doesn’t love a wall, That wants it down.’ I could say ‘Elves’ to him, But it’s not elves exactly, and I’d rather He said it for himself. I see him there Bringing a stone grasped firmly by the top In each hand, like an old-stone savage armed.

(“Mending Wall” by Robert Frost)

Robert Frost uses many examples of comparisons in his poetry in order to create stronger imagery . In this excerpt from “Mending Wall,” the speaker and his neighbor walk along the wall that divides them, trying to put it back together. While the neighbor likes this wall, and affirms that “good fences make good neighbors,” the speaker is suspicious of this premise. The speaker uses the simile of his neighbor looking like “an old-stone savage armed,” which creates a sense that the neighbor is more like a caveman than a modern human, and that his opinions are similarly outdated.

Gatsby believed in the green light, the orgastic future that year by year recedes before us. It eluded us then, but that’s no matter—tomorrow we will run faster, stretch out our arms farther…. And then one fine morning— So we beat on, boats against the current, borne back ceaselessly into the past.

( The Great Gatsby by F. Scott Fitzgerald)

This excerpt from F. Scott Fitzgerald’s classic The Great Gatsby comprises the final few lines of the novel. There is a strong sense of nostalgia that Fitzgerald relates through this ending. He does this by creating the metaphor of the characters trying to travel into the future against a current that pulls them back into reflections on their past. This example of comparison is an excellent metaphor in that in describes the familiar relationship of trying to row against the current with a more intangible experience.

TOM: But the wonderfullest trick of all was the coffin trick. We nailed him into a coffin and he got out of the coffin without removing one nail. . . . There is a trick that would come in handy for me—get me out of this two-by-four situation! . . . You know it don’t take much intelligence to get yourself into a nailed-up coffin, Laura. But who in hell ever got himself out of one without removing one nail?

( The Glass Menagerie by Tennessee Williams)

In this excerpt from Tennessee Williams’s play The Glass Menagerie , the protagonist Tom compares his own life to the magician’s trick of getting out of a nailed-up coffin. This is a particularly striking example of comparison because from the outside Tom’s life might not look so terrible. Clearly, however, he views it as a prison that is nearly impossible to escape.

So Gen should have said something more, and Carmen should have listened more, but instead she kissed him, because the important thing was to forget. That kiss was like a lake, deep and clear, and they swam into it forgetting.

( Bel Canto by Ann Patchett)

This evocative comparison example comes from the contemporary author Ann Patchett’s novel Bel Canto . In it, she compares a kiss between two characters to a lake. This is an interesting comparison because it is unusual, and perhaps not one that the reader will have thought of before. Patchett justifies this comparison with the beautiful idea of the characters swimming into the kiss, as they might have done into a lake, forgetting the dangerous situation they are in.

Test Your Knowledge of Comparison in Literature

1. Which of the following statements is the best comparison definition? A. Describing two or more things in relation to each other. B. Showing that one thing is better than another. C. Showing how two things are dissimilar.

2. Which type of comparison can be found in the following quote from William Shakespeare’s tragedy Othello?

Oh, beware, my lord, of jealousy! It is the green-eyed monster which doth mock The meat it feeds on.

A. Pun B. Allegory C. Metaphor

3. Which of the following lines from Robert Frost poetry contains a comparison example? A.

For I have had too much Of apple-picking: I am overtired Of the great harvest I myself desired.

(“After Apple Picking”) B.

You may see their trunks arching in the woods Years afterwards, trailing their leaves on the ground Like girls on hands and knees that throw their hair Before them over their heads to dry in the sun.

(“Birches”) C.

Whose woods these are I think I know. His house is in the village though; He will not see me stopping here To watch his woods fill up with snow.

(“Stopping by Woods on a Snowy Evening”)

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10.7 Comparison and Contrast

Learning objectives.

Determine the purpose and structure of comparison and contrast in writing.
Explain organizational methods used when comparing and contrasting.
Understand how to write a compare-and-contrast essay.

The Purpose of Comparison and Contrast in Writing

Comparison in writing discusses elements that are similar, while contrast in writing discusses elements that are different. A compare-and-contrast essay , then, analyzes two subjects by comparing them, contrasting them, or both.

The key to a good compare-and-contrast essay is to choose two or more subjects that connect in a meaningful way. The purpose of conducting the comparison or contrast is not to state the obvious but rather to illuminate subtle differences or unexpected similarities. For example, if you wanted to focus on contrasting two subjects you would not pick apples and oranges; rather, you might choose to compare and contrast two types of oranges or two types of apples to highlight subtle differences. For example, Red Delicious apples are sweet, while Granny Smiths are tart and acidic. Drawing distinctions between elements in a similar category will increase the audience’s understanding of that category, which is the purpose of the compare-and-contrast essay.

Similarly, to focus on comparison, choose two subjects that seem at first to be unrelated. For a comparison essay, you likely would not choose two apples or two oranges because they share so many of the same properties already. Rather, you might try to compare how apples and oranges are quite similar. The more divergent the two subjects initially seem, the more interesting a comparison essay will be.

Writing at Work

Comparing and contrasting is also an evaluative tool. In order to make accurate evaluations about a given topic, you must first know the critical points of similarity and difference. Comparing and contrasting is a primary tool for many workplace assessments. You have likely compared and contrasted yourself to other colleagues. Employee advancements, pay raises, hiring, and firing are typically conducted using comparison and contrast. Comparison and contrast could be used to evaluate companies, departments, or individuals.

Brainstorm an essay that leans toward contrast. Choose one of the following three categories. Pick two examples from each. Then come up with one similarity and three differences between the examples.

Romantic comedies
Internet search engines
Cell phones

Brainstorm an essay that leans toward comparison. Choose one of the following three items. Then come up with one difference and three similarities.

Department stores and discount retail stores
Fast food chains and fine dining restaurants
Dogs and cats

The Structure of a Comparison and Contrast Essay

The compare-and-contrast essay starts with a thesis that clearly states the two subjects that are to be compared, contrasted, or both and the reason for doing so. The thesis could lean more toward comparing, contrasting, or both. Remember, the point of comparing and contrasting is to provide useful knowledge to the reader. Take the following thesis as an example that leans more toward contrasting.

Thesis statement: Organic vegetables may cost more than those that are conventionally grown, but when put to the test, they are definitely worth every extra penny.

Here the thesis sets up the two subjects to be compared and contrasted (organic versus conventional vegetables), and it makes a claim about the results that might prove useful to the reader.

You may organize compare-and-contrast essays in one of the following two ways:

According to the subjects themselves, discussing one then the other
According to individual points, discussing each subject in relation to each point

See Figure 10.1 “Comparison and Contrast Diagram” , which diagrams the ways to organize our organic versus conventional vegetables thesis.

Figure 10.1 Comparison and Contrast Diagram

The organizational structure you choose depends on the nature of the topic, your purpose, and your audience.

Given that compare-and-contrast essays analyze the relationship between two subjects, it is helpful to have some phrases on hand that will cue the reader to such analysis. See Table 10.3 “Phrases of Comparison and Contrast” for examples.

Table 10.3 Phrases of Comparison and Contrast

Create an outline for each of the items you chose in Note 10.72 “Exercise 1” and Note 10.73 “Exercise 2” . Use the point-by-point organizing strategy for one of them, and use the subject organizing strategy for the other.

Writing a Comparison and Contrast Essay

First choose whether you want to compare seemingly disparate subjects, contrast seemingly similar subjects, or compare and contrast subjects. Once you have decided on a topic, introduce it with an engaging opening paragraph. Your thesis should come at the end of the introduction, and it should establish the subjects you will compare, contrast, or both as well as state what can be learned from doing so.

The body of the essay can be organized in one of two ways: by subject or by individual points. The organizing strategy that you choose will depend on, as always, your audience and your purpose. You may also consider your particular approach to the subjects as well as the nature of the subjects themselves; some subjects might better lend themselves to one structure or the other. Make sure to use comparison and contrast phrases to cue the reader to the ways in which you are analyzing the relationship between the subjects.

After you finish analyzing the subjects, write a conclusion that summarizes the main points of the essay and reinforces your thesis. See Chapter 15 “Readings: Examples of Essays” to read a sample compare-and-contrast essay.

Many business presentations are conducted using comparison and contrast. The organizing strategies—by subject or individual points—could also be used for organizing a presentation. Keep this in mind as a way of organizing your content the next time you or a colleague have to present something at work.

Choose one of the outlines you created in Note 10.75 “Exercise 3” , and write a full compare-and-contrast essay. Be sure to include an engaging introduction, a clear thesis, well-defined and detailed paragraphs, and a fitting conclusion that ties everything together.

Key Takeaways

A compare-and-contrast essay analyzes two subjects by either comparing them, contrasting them, or both.
The purpose of writing a comparison or contrast essay is not to state the obvious but rather to illuminate subtle differences or unexpected similarities between two subjects.
The thesis should clearly state the subjects that are to be compared, contrasted, or both, and it should state what is to be learned from doing so.

There are two main organizing strategies for compare-and-contrast essays.

Organize by the subjects themselves, one then the other.
Organize by individual points, in which you discuss each subject in relation to each point.
Use phrases of comparison or phrases of contrast to signal to readers how exactly the two subjects are being analyzed.

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Learning Objectives

Understand the common structures and uses of comparison and contrast writing.

One of the most common types of writing (and thinking) is comparison writing. When considering the pros and cons of a new purchase or decision, for instance, many of us use comparisons to existing models. Students are also often asked to compare something they’re reading with another similar text. Reviews of popular media also often compare or contrast: consider the line, “Her best work since…” which offers a direct comparison with a previous performance.

Comparison and contrast essays, however, often get the reputation of being boring or sounding automatic. While the form is useful, it is also plain, and it can inspire uninspiring writing. This chapter aims to help you understand when comparison is appropriate, the terms that we use to talk about it, how to structure it, and then how to use those structures in a meaningful and creative way across media.

What is Comparison and Contrast Writing?

Comparison and Contrast writing is used to show a reader the similarities and/or differences between two subjects. Comparison writing focuses on similarities (ways things are alike), while contrast writing focuses on differences or ways they are not alike.

In order to do this, the subjects chosen have to be related or share at least some characteristics. You may have heard that it’s impossible to compare apples and oranges. This isn’t true, of course: an apple can easily be compared to an orange, since they both share many characteristics (both fruit, both vaguely round, both on sale at the store, both considered nutritious, etc.). However, some items would be very difficult to compare: writing a short essay comparing a Fuji apple to an Apple MacBook might result in no meaningful similarities. That paper would, likely, be a waste of a reader’s (and writer’s) time.

Meaningful comparison, however, can enlighten an audience toward unknown similarities or differences between subjects. The more informative or surprising a comparative is, the more likely an audience is to be engaged. For example, writing a paper that compares two well-known superheroes and discusses their similarities might not be that interesting. Showing how alike a superhero and a villain are, though, might subvert the audience’s expectation (that heroes and villains have nothing in common), which could lead to a more interesting paper.

Some assignments will specifically ask for a comparison or a contrast. Others may want you to incorporate both. Read carefully to find what’s most appropriate.

Here are a few example essay prompts that might lead to comparison/contrast writing:

What are the major similarities and differences between the Honda Hobbit and the Ford Frodo? (Asks for compare/contrast)
Discuss the leadership styles of Ulysses S. Grant and Robert E. Lee. (Could be comparing/contrasting)
How do recent behaviors around social media compare to the early introduction of the telegraph? (Asks for comparison, but may also want contrast)

Objective versus Subjective Comparison

The purpose of a comparison/contrast paper seems obvious – we’re talking about similarities/differences between two subjects to better inform our readers. However, there’s sometimes a secondary purpose to these papers: Comparison papers are often written to convince a reader that one subject is superior to the other.

Compare and contrast the SmartPhone A to the new SmartPhone AX. Which is better for a student?
Compare two presidents from the 19th century. Which one practiced better military leadership?

A subjective comparison includes factual information about both subjects but may also include the writer’s opinions. It may also work to convince a reader to consider one subject to be better than the other. Subjective comparisons also include the writer’s evaluation of the information. For instance, a writer will present facts about SmartPhone A, analysis of these facts, and their own opinion: [Fact] SmartPhone A is less expensive than SmartPhone AX by nearly $100, which [Analysis] makes it a better buy for most students. However, I’d [opinion] easily pay $100 to get a phone as sleek as the AX.

In addition, a subjective comparison will lead toward a conclusion at the end, deciding between the subjects being compared. This means that subjective comparison papers often function as argumentative writing, though they spend a good deal of time with the second subject.

By contrast, an objective comparison paper does not automatically seek to decide between options when it begins. It may list the categories for comparison that the subjects will be judged against, but it will build toward its conclusion through presenting facts, evidence, and analysis, not through subjective evaluation. An objective comparison is an informative paper, not an argumentative paper. Nevertheless, at the end, it may draw the conclusion that one side is better than the other, within the set of criteria established.

What’s that all mean? Here’s an example: An objective comparison of two types of smartphone would include factual information about both phones, like price, weight, available apps, camera resolution, and maybe a roundup of how they’ve been reviewed by credible sources. The author might find that college students have said the three most important things they look for in a phone are price, plans available, and apps available, so at the end of the piece, they could say, Based on the information presented here, the SmartPhone A would be a better buy for the average college student.

In a subjective opinion of the same two phones, the author would likely tell the audience as they start which phone is superior, and then spend the paper proving why by comparing the two. They would also present facts (cost, plans, apps, etc.), but they would add information from personal experience and their opinion of why some features are better than other.

A reader who wants to know more about the two phones before making her own decision would likely appreciate an objective comparison, while a reader who trusts the writer and wants to hear their opinion on the subject would likely appreciate a subjective comparison.

Getting started with comparison writing

The place to start with comparison writing is in choosing your subjects. Usually, this will involve two subjects (though longer papers might engage with more). Subjects are the main people, things, places, or ideas that we’ll be comparing or contrasting throughout the paper. Subjects must be related in some way. For example, I might choose to compare two college courses: even if their subjects are very different, because they are both classes, I will likely find ways to compare them.

Next, after researching the subjects, you’ll establish the points of comparison that you’ll use. These are the criteria that you’ll use to compare the two subjects, and they are your decision as a writer. For a short (3-5) page paper, you’ll usually select 3-4 points. Above, in the smartphone example, my points were: cost, app availability, plan pricing, weight, camera resolution, and reviews. I would likely narrow these down to focusing on three points.

How do I select points? This is generally where considering your audience comes into play: What would they be most interested in or convinced by? If I’m writing for a cost-conscious audience who also wants to be able to play games, I’d likely narrow down to cost, plan pricing, and apps available. I might choose something different (like durability or available security measures) if I was writing a paper to be read by parents of young children. The choice of comparison points is up to the writer, and your research should guide the decision you make. You’ll need to write about the same points for each subject.

Structuring comparison writing

The comparison essay can follow a set outline. In fact, two structures are common for comparison writing: the Point-by-Point structure and the Subject-by-Subject or Block structure. Both have advantages. They can also be combined, as needed.

Subject-by-Subject (Block) Structure

In subject-by-subject comparisons, each subject is tackled separately. After an introduction paragraph (covered later in this chapter), the paper goes directly into a section (one paragraph or multiple paragraphs) that addresses the first subject. This allows time to describe the subject for an unfamiliar audience or to place a concept in context. Then, after a transition, the second subject is discussed.

Within each section, the same points for comparison will be covered in approximately the same order and depth. Here’s an example outline for a subject-by-subject paper, written about two different types of smartphones:

Introduction

General description of the phone
Available pricing plans
Available apps

Though it may appear that this essay is only four paragraphs long, it is useful to think of each number as a “section,” instead of a paragraph. The description might run for an entire paragraph when comparing two complex subjects: Consider, for example, an essay that wants to compare two video games. The first part of the subject discussion might be only about how the game is played and its major objectives, while the next paragraph would talk about its cost, time to play, and popular reviews.

Generally, in a subject-by-subject paper, during the second subject area (section 3), the writer will use comparison words to start reminding the reader of how things line up (or don’t) with the first subject.

Common Comparison/Contrast Words:

In contrast
On the other hand
As shown before
Almost like

Point-by-point structure

In point-by-point comparison writing, the work is organized around the criteria for comparison. A sample outline would look like this:

Cost of Smartphone A
Cost of Smartphone AX
Plans for Smartphone A
Plans for Smartphone AX
Apps on Smartphone A
Apps on Smartphone AX

The point-by-point structure means that both subjects are discussed side by side throughout the paper, which can be a great way to line up complicated topics or subjects which require frequent references to numbers. For example, in a paper comparing two potential vacation choices, the cost of many pieces of the trip might be important to see side by side: “If we travel to Island A, plane tickets will cost $476 per person, while Island B will cost $345 per person but will include a $50 baggage charge and a $20 shuttle ride.”

Point-by-point structure allows a writer to emphasize the importance of the categories for comparison over the subjects themselves. It can be a good format for informative papers or for papers where the comparison criteria are complex. For example, in our smartphone example, it may be difficult to explain why pricing plans for phones are so wildly different. A point-by-point structure would allow the writer to offer a quick explanation of types of plans before diving in to say how the two subjects stack up.

Though it may appear to be a longer structure than subject-by-subject, this is not necessarily true; again, think of the parts of the outline as sections instead of paragraphs, knowing that some parts may require more space to deal with than others.

Both outlines require the writer to frequently use comparison words and phrases. They also can be expanded to meet the needs of the assignment.

Comparison Introduction, Thesis, and Conclusion

A comparison paper will begin with an introduction paragraph. This paragraph should, at minimum, establish for the reader that they are about to read a comparison/contrast essay. While that seems obvious, it’s easy to start a paper by talking only about one subject, or only about one point for comparison, which might lead a reader to think they’re going to read about only one idea. It can be useful to start the paper by describing why it’s important to study the differences or similarities between the two subjects: could it make a difference in the reader’s opinion or behavior?

If a comparison or contrast is being made between two subjects that will require the audience to have additional background knowledge, a secondary introduction may be necessary. For instance, if I were writing a paper comparing two characters from the Star Wars series, but my audience wasn’t guaranteed to have seen the films, I might put in a second paragraph that briefly described the plots of the relevant movies before getting into my character comparisons.

Though by no means the only right place to put it, many comparison essays will have a thesis at the end of the first paragraph. The comparison thesis will name both subjects and will state whether they will be compared, contrasted, or both. An excellent thesis will also remind the reader of the importance of this comparison.

Example Thesis Statements

Smartphone A and Smartphone AX look alike in the store, but a cost-conscious student should study their similarities and differences in price, plans, and apps to find which one will be the best fit.
Though they were similarly popular as toys, R2-D2 and BB-8 served very different purposes in the Star Wars universe and continue to show the ways the movies have evolved.
Harry Potter and Hermione Granger had radically different methods of studying, which could have led readers to favor one character over another.

The final section in a comparison paper is left for the conclusion. This can be a simple wrap-up, where the thesis is re-stated and the major points are reviewed. However, a comparison can also end with an additional discussion section, where the author considers and analyzes the two subjects and recommends or predicts which will be a better fit for the audience. In the smartphone example, a paragraph or two at the end might be reserved to discuss the features that weren’t described and why they aren’t as important, or to mention that both phones will soon be outdated. Discussion can be a useful way to bring in additional information or to place everything else in context.

Key Takeaways

Comparison/Contrast writing is frequently required in school and work settings. Keep in mind:

Subjects are the main people, places, things, or ideas/concepts to be compared or contrasted (or both)
Points are the criteria used to compare these subjects, and both subjects must be compared using the same points
A subjective comparison draws a conclusion or evaluates the subjects at the end, based on the writer’s opinion.
An objective comparison lets a reader become better informed about the subjects and allows them to draw their own conclusion
Two structures (subject-by-subject or point-by-point) are usually used in basic comparison writing.

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Thesis, Analysis, & Structure

Comparing and Contrasting

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The professor says to compare and contrast A and B ...

Determining the Structure of your Essay:

Determining the structure of your essay is the most important step towards conducting and presenting to the reader a well-developed comparison. Students are often asked to compare things in twos. For example, compare these two articles, or two characters in a novel, or a film and a novel or an article and a poem... The possibilities are endless.

When you are faced with the task of having to compare and contrast, it can be overwhelming. You're thinking about two pieces of writing that you know are different, and perhaps there are some similarities, too, but how can you suddenly start talking about them both? Which one should I talk about first? Which one should I talk about last?

Sometimes, comparisons are done in the following manner:

You pick one article to describe: Article A. Then you talk about Article B. Perhaps at the end, you talk about the similarities in both articles.

This format will consist of three main parts: A, B, and, finally, their similarities.

Although this format is an acceptable way of making comparisons, and it is sometimes used to present well-developed "compare and contrast" essays, the format has its weaknesses that can jeopardize an effective comparison.

What could happen when you use this format and you completely isolate Article A from Article B is that you make it more difficult to compare. Your final essay might end up divided in two parts: half of the paper talks about only Article A and the second half talks about only Article B . You do not want to split your essay into a description of Article A and a description of Article B because then it will be harder to compare them since you invested most of your energy into describing them and not comparing them.

How to avoid the "Split Essay": A Second Option for Comparison

The best way to avoid the Split Essay is to unify both split ends. Do not discuss Article B at the end. Talk about both A and B from the beginning. The question now is:

What do I do to eliminate the Split?

Break it down:

You do not get rid of the gap between the two halves of the essay that are split. You simply break it down . This is done by finding common themes, or points of comparison in Article A and Article B. Once you find those points of comparison, you can discuss each individual theme and how each shows up in Article A and B . Consider the following questions:

What major themes are discussed in each of the essays?
What doe the writer of Article A say about the first theme, and how is this similar to or different than what the writer of Article B says about the same topic?
What conclusions can you make about these differences or similarities?

After developing a thorough explanation of the first theme, you can mow move on to discuss the second theme that appears in both essays and write about it. Ideally, each theme will be discussed thoroughly in its own paragraph, explaining how each is similar or different in Article A and Article B

During the seventies, Gabriel Garcia Marquez wrote his most famous novel, One Hundred Years of Solitude , in which he discussed themes regarding the solitude of Latin America.

In 1982, Marquez received the Nobel Prize in Literature for his novel and wrote a speech for this occasion. In his speech, he called attention to Latin American economic struggles and their historical context.

In 1990, Enrique Krauze, a Mexican economist, published an article in which he discussed the same topic: problems in Latin American economics.

The prompt says:

Compare and contrast Enrique Krauze's essay to the speech written by Marquez.

Possible approaches:

Option #1: Text by text comparison

First paragraph:

A: An explanation of Marquez's entire speech

Second paragraph:

B: An explanation of Krauze's entire essay

Third paragraph:

Similarities or differences

(this might lead to the "Split Essay" comparison)

Option #2: Point by point comparison

The breakdown: Finding common themes or points of comparison:

• Neoliberalism (free trade)

• US involvement

• Proposed solutions to the problems (macro or micro economy?)

A: Krauze's opinion on neoliberalism

B: Marquez's opinion on neoliberalism

A: US involvement good or bad? According to Marquez

B: US involvement good or bad? According to Krauze

Whatever other theme that stands out as significant for explaining the differences of opinions.

Sample paragraph:

Enrique Krauze and Gabriel Garcia Marquez take different positions in regards to the implementation of more neoliberalist policies in Latin American countries. While Krauze argues the need to expand open trade in Latin America to improve its economy, Marquez opposes this idea and argues that an open trade economy would only aid foreign investors in further exploiting the natural resources in Latin America. Krauze's support of neoliberalism is based on the idea that through a macro economy, the "undeveloped" countries will soon see the light at the end of the tunnel. On the other hand, Marquez rebuts this argument, claiming that the World Bank and the International Monetary Fund, which forced neoliberalist policies onto Latin American countries, only served to increase their foreign debt.

Notice how the beginning of this paragraph discusses only one theme: neoliberalism. Also notice how the writer was able to incorporate both articles and not just one. Pay attention, too, to the use of words and phrases that juxtapose or suggest comparison. These words establish links between A and B .

Handout created by Rubén Garibaldo, Student Learning Center, University of California, Berkeley

Handout revised by Carolyn Swalina, Student Learning Center, University of California, Berkeley

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.

The Writing Center • University of North Carolina at Chapel Hill

Comparing and Contrasting

What this handout is about.

This handout will help you first to determine whether a particular assignment is asking for comparison/contrast and then to generate a list of similarities and differences, decide which similarities and differences to focus on, and organize your paper so that it will be clear and effective. It will also explain how you can (and why you should) develop a thesis that goes beyond “Thing A and Thing B are similar in many ways but different in others.”

Introduction

In your career as a student, you’ll encounter many different kinds of writing assignments, each with its own requirements. One of the most common is the comparison/contrast essay, in which you focus on the ways in which certain things or ideas—usually two of them—are similar to (this is the comparison) and/or different from (this is the contrast) one another. By assigning such essays, your instructors are encouraging you to make connections between texts or ideas, engage in critical thinking, and go beyond mere description or summary to generate interesting analysis: when you reflect on similarities and differences, you gain a deeper understanding of the items you are comparing, their relationship to each other, and what is most important about them.

Recognizing comparison/contrast in assignments

Some assignments use words—like compare, contrast, similarities, and differences—that make it easy for you to see that they are asking you to compare and/or contrast. Here are a few hypothetical examples:

Compare and contrast Frye’s and Bartky’s accounts of oppression.
Compare WWI to WWII, identifying similarities in the causes, development, and outcomes of the wars.
Contrast Wordsworth and Coleridge; what are the major differences in their poetry?

Notice that some topics ask only for comparison, others only for contrast, and others for both.

But it’s not always so easy to tell whether an assignment is asking you to include comparison/contrast. And in some cases, comparison/contrast is only part of the essay—you begin by comparing and/or contrasting two or more things and then use what you’ve learned to construct an argument or evaluation. Consider these examples, noticing the language that is used to ask for the comparison/contrast and whether the comparison/contrast is only one part of a larger assignment:

Choose a particular idea or theme, such as romantic love, death, or nature, and consider how it is treated in two Romantic poems.
How do the different authors we have studied so far define and describe oppression?
Compare Frye’s and Bartky’s accounts of oppression. What does each imply about women’s collusion in their own oppression? Which is more accurate?
In the texts we’ve studied, soldiers who served in different wars offer differing accounts of their experiences and feelings both during and after the fighting. What commonalities are there in these accounts? What factors do you think are responsible for their differences?

You may want to check out our handout on understanding assignments for additional tips.

Using comparison/contrast for all kinds of writing projects

Sometimes you may want to use comparison/contrast techniques in your own pre-writing work to get ideas that you can later use for an argument, even if comparison/contrast isn’t an official requirement for the paper you’re writing. For example, if you wanted to argue that Frye’s account of oppression is better than both de Beauvoir’s and Bartky’s, comparing and contrasting the main arguments of those three authors might help you construct your evaluation—even though the topic may not have asked for comparison/contrast and the lists of similarities and differences you generate may not appear anywhere in the final draft of your paper.

Discovering similarities and differences

Making a Venn diagram or a chart can help you quickly and efficiently compare and contrast two or more things or ideas. To make a Venn diagram, simply draw some overlapping circles, one circle for each item you’re considering. In the central area where they overlap, list the traits the two items have in common. Assign each one of the areas that doesn’t overlap; in those areas, you can list the traits that make the things different. Here’s a very simple example, using two pizza places:

Venn diagram indicating that both Pepper's and Amante serve pizza with unusual ingredients at moderate prices, despite differences in location, wait times, and delivery options

To make a chart, figure out what criteria you want to focus on in comparing the items. Along the left side of the page, list each of the criteria. Across the top, list the names of the items. You should then have a box per item for each criterion; you can fill the boxes in and then survey what you’ve discovered.

As you generate points of comparison, consider the purpose and content of the assignment and the focus of the class. What do you think the professor wants you to learn by doing this comparison/contrast? How does it fit with what you have been studying so far and with the other assignments in the course? Are there any clues about what to focus on in the assignment itself?

Here are some general questions about different types of things you might have to compare. These are by no means complete or definitive lists; they’re just here to give you some ideas—you can generate your own questions for these and other types of comparison. You may want to begin by using the questions reporters traditionally ask: Who? What? Where? When? Why? How? If you’re talking about objects, you might also consider general properties like size, shape, color, sound, weight, taste, texture, smell, number, duration, and location.

Two historical periods or events

When did they occur—do you know the date(s) and duration? What happened or changed during each? Why are they significant?
What kinds of work did people do? What kinds of relationships did they have? What did they value?
What kinds of governments were there? Who were important people involved?
What caused events in these periods, and what consequences did they have later on?

Two ideas or theories

What are they about?
Did they originate at some particular time?
Who created them? Who uses or defends them?
What is the central focus, claim, or goal of each? What conclusions do they offer?
How are they applied to situations/people/things/etc.?
Which seems more plausible to you, and why? How broad is their scope?
What kind of evidence is usually offered for them?

Two pieces of writing or art

What are their titles? What do they describe or depict?
What is their tone or mood? What is their form?
Who created them? When were they created? Why do you think they were created as they were? What themes do they address?
Do you think one is of higher quality or greater merit than the other(s)—and if so, why?
For writing: what plot, characterization, setting, theme, tone, and type of narration are used?
Where are they from? How old are they? What is the gender, race, class, etc. of each?
What, if anything, are they known for? Do they have any relationship to each other?
What are they like? What did/do they do? What do they believe? Why are they interesting?
What stands out most about each of them?

Deciding what to focus on

By now you have probably generated a huge list of similarities and differences—congratulations! Next you must decide which of them are interesting, important, and relevant enough to be included in your paper. Ask yourself these questions:

What’s relevant to the assignment?
What’s relevant to the course?
What’s interesting and informative?
What matters to the argument you are going to make?
What’s basic or central (and needs to be mentioned even if obvious)?
Overall, what’s more important—the similarities or the differences?

Suppose that you are writing a paper comparing two novels. For most literature classes, the fact that they both use Caslon type (a kind of typeface, like the fonts you may use in your writing) is not going to be relevant, nor is the fact that one of them has a few illustrations and the other has none; literature classes are more likely to focus on subjects like characterization, plot, setting, the writer’s style and intentions, language, central themes, and so forth. However, if you were writing a paper for a class on typesetting or on how illustrations are used to enhance novels, the typeface and presence or absence of illustrations might be absolutely critical to include in your final paper.

Sometimes a particular point of comparison or contrast might be relevant but not terribly revealing or interesting. For example, if you are writing a paper about Wordsworth’s “Tintern Abbey” and Coleridge’s “Frost at Midnight,” pointing out that they both have nature as a central theme is relevant (comparisons of poetry often talk about themes) but not terribly interesting; your class has probably already had many discussions about the Romantic poets’ fondness for nature. Talking about the different ways nature is depicted or the different aspects of nature that are emphasized might be more interesting and show a more sophisticated understanding of the poems.

Your thesis

The thesis of your comparison/contrast paper is very important: it can help you create a focused argument and give your reader a road map so she/he doesn’t get lost in the sea of points you are about to make. As in any paper, you will want to replace vague reports of your general topic (for example, “This paper will compare and contrast two pizza places,” or “Pepper’s and Amante are similar in some ways and different in others,” or “Pepper’s and Amante are similar in many ways, but they have one major difference”) with something more detailed and specific. For example, you might say, “Pepper’s and Amante have similar prices and ingredients, but their atmospheres and willingness to deliver set them apart.”

Be careful, though—although this thesis is fairly specific and does propose a simple argument (that atmosphere and delivery make the two pizza places different), your instructor will often be looking for a bit more analysis. In this case, the obvious question is “So what? Why should anyone care that Pepper’s and Amante are different in this way?” One might also wonder why the writer chose those two particular pizza places to compare—why not Papa John’s, Dominos, or Pizza Hut? Again, thinking about the context the class provides may help you answer such questions and make a stronger argument. Here’s a revision of the thesis mentioned earlier:

Pepper’s and Amante both offer a greater variety of ingredients than other Chapel Hill/Carrboro pizza places (and than any of the national chains), but the funky, lively atmosphere at Pepper’s makes it a better place to give visiting friends and family a taste of local culture.

You may find our handout on constructing thesis statements useful at this stage.

Organizing your paper

There are many different ways to organize a comparison/contrast essay. Here are two:

Subject-by-subject

Begin by saying everything you have to say about the first subject you are discussing, then move on and make all the points you want to make about the second subject (and after that, the third, and so on, if you’re comparing/contrasting more than two things). If the paper is short, you might be able to fit all of your points about each item into a single paragraph, but it’s more likely that you’d have several paragraphs per item. Using our pizza place comparison/contrast as an example, after the introduction, you might have a paragraph about the ingredients available at Pepper’s, a paragraph about its location, and a paragraph about its ambience. Then you’d have three similar paragraphs about Amante, followed by your conclusion.

The danger of this subject-by-subject organization is that your paper will simply be a list of points: a certain number of points (in my example, three) about one subject, then a certain number of points about another. This is usually not what college instructors are looking for in a paper—generally they want you to compare or contrast two or more things very directly, rather than just listing the traits the things have and leaving it up to the reader to reflect on how those traits are similar or different and why those similarities or differences matter. Thus, if you use the subject-by-subject form, you will probably want to have a very strong, analytical thesis and at least one body paragraph that ties all of your different points together.

A subject-by-subject structure can be a logical choice if you are writing what is sometimes called a “lens” comparison, in which you use one subject or item (which isn’t really your main topic) to better understand another item (which is). For example, you might be asked to compare a poem you’ve already covered thoroughly in class with one you are reading on your own. It might make sense to give a brief summary of your main ideas about the first poem (this would be your first subject, the “lens”), and then spend most of your paper discussing how those points are similar to or different from your ideas about the second.

Point-by-point

Rather than addressing things one subject at a time, you may wish to talk about one point of comparison at a time. There are two main ways this might play out, depending on how much you have to say about each of the things you are comparing. If you have just a little, you might, in a single paragraph, discuss how a certain point of comparison/contrast relates to all the items you are discussing. For example, I might describe, in one paragraph, what the prices are like at both Pepper’s and Amante; in the next paragraph, I might compare the ingredients available; in a third, I might contrast the atmospheres of the two restaurants.

If I had a bit more to say about the items I was comparing/contrasting, I might devote a whole paragraph to how each point relates to each item. For example, I might have a whole paragraph about the clientele at Pepper’s, followed by a whole paragraph about the clientele at Amante; then I would move on and do two more paragraphs discussing my next point of comparison/contrast—like the ingredients available at each restaurant.

There are no hard and fast rules about organizing a comparison/contrast paper, of course. Just be sure that your reader can easily tell what’s going on! Be aware, too, of the placement of your different points. If you are writing a comparison/contrast in service of an argument, keep in mind that the last point you make is the one you are leaving your reader with. For example, if I am trying to argue that Amante is better than Pepper’s, I should end with a contrast that leaves Amante sounding good, rather than with a point of comparison that I have to admit makes Pepper’s look better. If you’ve decided that the differences between the items you’re comparing/contrasting are most important, you’ll want to end with the differences—and vice versa, if the similarities seem most important to you.

Our handout on organization can help you write good topic sentences and transitions and make sure that you have a good overall structure in place for your paper.

Cue words and other tips

To help your reader keep track of where you are in the comparison/contrast, you’ll want to be sure that your transitions and topic sentences are especially strong. Your thesis should already have given the reader an idea of the points you’ll be making and the organization you’ll be using, but you can help her/him out with some extra cues. The following words may be helpful to you in signaling your intentions:

like, similar to, also, unlike, similarly, in the same way, likewise, again, compared to, in contrast, in like manner, contrasted with, on the contrary, however, although, yet, even though, still, but, nevertheless, conversely, at the same time, regardless, despite, while, on the one hand … on the other hand.

For example, you might have a topic sentence like one of these:

Compared to Pepper’s, Amante is quiet.
Like Amante, Pepper’s offers fresh garlic as a topping.
Despite their different locations (downtown Chapel Hill and downtown Carrboro), Pepper’s and Amante are both fairly easy to get to.

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Comparison Definition Comparison is a rhetorical or literary tool wherein a author compares or contrasts two humans, places, things, or ideas. In our ordinary existence, we compare people and matters to express ourselves vividly. So while we say, someone is “as lazy as a snail,” you examine exclusive entities to show similarity i.E. someone’s laziness to the sluggish tempo of a snail. Comparisons occur in literary works frequently. Writers and poets use contrast as a way to hyperlink their emotions approximately a component to something readers can apprehend. There are numerous gadgets in literature that examine two different matters to reveal the similarity between them, together with simile, metaphor, and analogy. Examples of Comparison in Literature In the following comparison examples, we are able to try to analyze literary gadgets used to expose comparisons. Metaphor A metaphor makes a hidden assessment between two matters or items which can be distinct to every other, however have a few characteristics commonplace between them. Unlike simile, we do not use “like” or “as” to broaden a contrast in a metaphor. Consider the subsequent examples: Example #1: When I Have Fears (By John Keats) These strains are from When I Have Fears, by using John Keats. “Before high-pil’d books, in charact’ry Hold like rich garners the full-ripened grain,” John Keats compares writing poetry with reaping and sowing, and each those acts stand for the insignificance of a lifestyles and dissatisfied creativity. Example #2: As You Like It (By William Shakespeare) This line is from As You Like It, by using William Shakespeare. “All the global’s a level and ladies and men simply players…” Shakespeare uses a metaphor of a level to describe the international, and compares males and females living inside the global with players (actors). Simile A simile is an open contrast among things or items to show similarities between them. Unlike a metaphor, a simile draws resemblance with the assist of words “like” or “as.” Example #3: Lolita (By Vladimir Nabokov) This line is from the quick story Lolita, by Vladimir Nabokov. “Elderly American ladies leaning on their canes listed towards me like towers of Pisa.” In this line, Vladimir Nabokov compares old ladies leaning on their sticks to the Leaning Tower of Pisa. Here the contrast made between two contrasting things creates a hilarious effect. Analogy An analogy goals at explaining an unusual idea or thing, by means of evaluating it to something this is acquainted. Example #4: The Noiseless Patient Spider (By Walt Whitman) These traces are from Walt Whitman’s poem The Noiseless Patient Spider“: “And you O my soul wherein you stand, Surrounded, detached, in measureless oceans of space, Ceaselessly musing, venturing, throwing, searching for the spheres to connect them, Till the bridge you will want be form’d, until the ductile anchor hold, Till the gossamer thread you fling seize somewhere, O my soul.” Walt Whitman uses an analogy to expose similarity between a spider spinning a web and his soul. Example #5: Night Clouds (By Amy Lowell) These strains are from Night Clouds, written by Amy Lowell: “The white mares of the moon rush alongside the sky Beating their golden hoofs upon the glass Heavens.” Amy constructs an analogy between clouds and mares. She compares the motion of the white clouds inside the sky at night with the motion of white mares at the ground. Allegory An allegory makes use of symbols to evaluate folks or matters, to represent abstract thoughts or events. The evaluation in allegory is implicit. Example #6: Animal Farm (By George Orwell) Animal Farm, written by way of George Orwell, is an allegory that compares animals on a farm to the Communist Revolution in Russia earlier than WW II. The actions of the animals on the farm can be as compared with the greed and corruption after the revolution. The animals on the farm represent different sections of Russian society after the revolution. For instance, “Pigs” can be as compared to people who became the authority after the revolution;”Mr. Jones,” the owner of the farm, is likened to the overthrown Tsar Nicholas II; and “Boxer,” the horse, stands for the laborer class. Example #7: Faerie Queen (By Edmund Spenser) Faerie Queen is an allegory with the aid of Edmund Spenser, in which the coolest characters of the book can be in comparison to the various virtues, even as the horrific characters can be in comparison to vices. For example, “The Red-Cross Knight” represents Holiness, and “Lady Una” Truth, Wisdom, and Goodness. Her mother and father signify the Human Race, and the “Dragon,” which has imprisoned them, stands for Evil. Function of Comparison The above examples of contrast help us recognise that, in general, writers utilize different sorts of assessment to hyperlink an strange or a new idea to not unusual and familiar items. It helps readers to realise a new concept, which might also have been tough for them to understand otherwise. The expertise of a new idea turns out to be less complicated when viewed with a contrast to something this is familiar to them. In addition, by means of making use of numerous literary equipment for assessment, writers boom their chances of catching the attention and hobby in their readers, as comparisons help them perceive what they're analyzing to their lives.

Alliteration
Anachronism
Antimetabole
Aposiopesis
Characterization
Colloquialism
Connotation
Deus Ex Machina
Didacticism
Doppelganger
Double Entendre
Flash Forward
Foreshadowing
Internal Rhyme
Juxtaposition
Non Sequitur
Onomatopoeia
Parallelism
Pathetic Fallacy
Personification
Poetic Justice
Point of View
Portmanteau
Protagonist
Red Herring
Superlative
Synesthesia
Tragicomedy
Tragic Flaw
Verisimilitude

Effectiviology

The Contrast Effect: When Comparison Enhances Differences

The contrast effect is a cognitive bias that distorts our perception of something when we compare it to something else, by enhancing the differences between them. This comparison can be either explicit or implicit, simultaneous or at separate points in time, and can apply to various traits, ranging from physical qualities, such as color and taste, to more abstract qualities, such as price and attractiveness.

For example, the contrast effect can make an item appear lighter than it actually is when it’s placed against a dark background, or it can make an expensive product appear cheaper when it’s presented next to a more expensive product.

The contrast effect plays a role in a wide variety of situations, so it can be highly beneficial to understand it. As such, in the following article you will learn more about the contrast effect, understand why people experience it, and see what you can do in order to account for its influence.

Examples of the contrast effect

A simple example of the contrast effect appears in the image below, where the grey square that’s placed on the light background appears darker than the grey square that’s placed on the dark background, despite the fact that they’re both the exact same color:

Another example of the contrast effect appears in the literary technique called juxtaposition , in which two elements, such as characters, actions, events, or ideas, are mentioned one after the other with the goal of emphasizing the differences between them. For instance, consider the following famous example of juxtaposition in literature:

“It was the best of times, it was the worst of times, it was the age of wisdom, it was the age of foolishness, it was the epoch of belief, it was the epoch of incredulity, it was the season of Light, it was the season of Darkness, it was the spring of hope, it was the winter of despair, we had everything before us, we had nothing before us, we were all going direct to Heaven, we were all going direct the other way…” — The opening to Charles Dickens’s “ A Tale of Two Cities ” (1859)

Furthermore, the contrast effect can influence people’s thinking in a variety of other ways. Examples of the influence of the contrast effect include the following:

Sweet drinks generally taste sweeter if you drink them right after drinking something that is less sweet, compared to when you drink them right after drinking something sweeter .
People sometimes feel that they’re more physically attractive after they look at pictures of people who are relatively unattractive .
Students sometimes feel less confident in their academic abilities when they’re in a class that has a lot of high-performing students .

Note : the last example, of students feeling less confident when they’re in a class with many high-performing students, has to do with a related social phenomenon , called the big-fish—little-pond effect , which is often discussed in the context of the contrast effect. It occurs when people feel better about their performance in some domain when they’re surrounded by people who have relatively low performance in that domain, compared to when they’re surrounded by people who have relatively high performance in the same domain.

Positive and negative contrast effects

In some cases, the contrast effect is categorized as belonging to one of two main types:

Positive contrast effects. A positive contrast effect occurs when something is perceived as better than it would usually be perceived, because it’s compared to something worse . For example, a positive contrast effect could cause a book cover to appear more interesting than usual if it’s placed next to a book with a boring cover.
Negative contrast effects. A negative contrast effect occurs when something is perceived as worse than it would usually be perceived, because it’s compared to something better . For example, a negative contrast effect could cause a car to appear cheaper than usual if it’s parked next to an expensive car.

This categorization scheme is generally only used when the trait in question can be evaluated as ‘better’ or ‘worse’. This is applicable, for example, when people assess traits such as attractiveness or intelligence, or factors such as the price of a product.

However, this categorization does not apply in the case of traits that can’t be classified as ‘better’ or ‘worse’, such as color or sound levels.

Why people experience the contrast effect

Because of the wide range of situations and ways in which people can experience contrast effects, there is no single mechanism that is used to explain this phenomenon. However, all explanations of the contrast effect have to do with the way in which our cognitive system intuitively utilizes comparisons when it processes and evaluates information.

For example, when people assess objects or entities that they encounter, they often intuitively compare them to similar objects/entities, or to their memory of them. This can, for instance, make an expensive product feel like it’s reasonably priced, if its price is intuitively compared to that of a more expensive product, even if we’re not interested in the more expensive alternative, and even if we would normally feel that the original product is significantly overpriced.

One notable psychological model that is used to explain the contrast effect is called the inclusion/exclusion model . Under this model, when we evaluate a certain entity based on its features, we have two mental representations: one of the target entity that we’re evaluating, and one of the standard against which we evaluate this target.

Based on this model, a contrast effect can occur when information is excluded from the mental representation of the target entity. This can happen various reasons, such as because people feel that the information doesn’t properly describe the target, or because they feel that it comes to mind for the wrong reason.

For example, consider a situation where someone is faced with an expensive target product, that is contrasted with a more expensive background product.

In this case, negative information regarding the high price of the target product might be excluded from its representation, as a result of the comparison to the more expensive background product. This, in turn, could cause the target to be perceived in a more positive manner than it usually would when compared against the standard that is used in order to represent products of this type, by making it appear less expensive, and thus more reasonably priced.

Furthermore, this excluded information can sometimes be used during the construction of the standard against which the target is compared. This could mean, for example, that if a certain negative trait of the target is ignored when it comes to the conceptualization of the target and is used instead to enhance the negativity of the standard against which the target is compared, then the target will be rated more positively in comparison.

There are other psychological models that are used to explain the contrast effect , many of which incorporate the inclusion/exclusion model to some degree.

Overall however, while the cognitive mechanisms responsible for the contrast effect are still being investigated, the main reason why people experience this bias is that the process which we use to process and evaluate information often relies on comparisons, regardless of whether or not those comparisons are to our benefit.

Note : the contrast effect is sometimes also referred to as the background contrast effect or the perceptual contrast effect .

Context effects: contrast and assimilation

The contrast effect is generally categorized as one of the two main types of context effects , which are cognitive biases that occur when comparisons with background information affect our evaluation of some stimuli.

The other main type of context effect is called the ‘assimilation effect’. The assimilation effect is a cognitive bias that distorts our perception of something when we compare it to something else, by reducing the apparent differences between them, which makes them appear more similar to one another. For example, the assimilation effect can influence people who see someone acting in a hostile manner, and cause them to view other people’s behavior as more hostile than they would otherwise.

The assimilation effect is therefore similar to the contrast effect, with the difference between the two being that the assimilation effect decreases the perceived difference between the things that are being compared, while the contrast effect increases this difference. Accordingly, the assimilation effect is seen as involving a positive relationship between the context information and the evaluation that people make, while the contrast effect is seen as having a negative relationship between the two.

Note : context effects are often discussed in conjunction with the concept of priming , which is a phenomenon where exposure to a stimulus subconsciously influences our response to consequent stimuli. In addition, another related phenomenon is anchoring , which similarly causes exposure to initial information to heavily influence future decisions.

Psychological mechanisms of assimilation and contrast

A notable psychological model that is used to explain why people can experience both types of context effects is the global/local processing model . This model suggests that global processing, which involves forming relatively abstract representations, leads to assimilation, while local processing, which involves forming more concrete representations, leads to contrast.

The model explains this phenomenon by saying that global processing leads to the inclusion of relevant information, which leads to assimilation by increasing the degree to which traits are perceived as shared between the representation of the target entity and the standard against which it’s compared. Conversely, local processing leads to exclusion of relevant information, which, as we saw in the section on why people experience the contrast effect, increases the perceived difference between the target and the standard.

Factors leading to contrast versus assimilation

A variety of factors can play a role when it comes to determining whether people experience a contrast effect or an assimilation effect.

For example, one study found that people are more likely to experience an assimilation effect if they focus on the similarities between the different options that are being assessed, while they are more likely to experience a contrast effect if they focus on the differences between them.

Similarly, another study found that when people view pictures of physically attractive people, they tend to rate their own attractiveness as higher afterward if they’re made to feel psychologically close to those people, by being told that they share similar attitudes and values. Furthermore, they display a similar assimilation effect after viewing pictures of unattractive people that they’re made to feel close to. Conversely, when people are shown pictures of people that they don’t feel psychologically close to, they experience a contrast effect, which causes them to feel less attractive after viewing pictures of attractive people, and more attractive after viewing pictures of unattractive people.

How to account for the contrast effect

In some situations, you may want to reduce the degree to which you are influenced by the contrast effect, in order to improve your ability to make rational decisions. This might be the case, for example, if a company’s marketing material is attempting to use contrast in order to make a certain product appear like a good deal, when in reality it’s overpriced.

In such situations, the main way to debias yourself is to break the connection between the main target item that you’re evaluating, and the alternative background items that it’s contrasted against. For example, if you’re trying to evaluate the price of a product, you would want to disconnect it from the background products that are used to justify its high cost.

To accomplish this, there are various approaches you can use. For example, you can:

Increase the distance between the options. Increasing the distance between the entities that you’re evaluating, in terms of factors such as time and space, can reduce the degree to which you experience a contrast effect between them.
Add more options. Throwing a variety of additional options into the mix can sometimes reduce the degree to which you notice the contrast between the initial options that you were presented with, because it makes it more difficult to compare them.
Explain why the comparison is irrelevant. Explaining to yourself why the comparison that you’re presented with is irrelevant, for example by focusing on the absolute price of a product rather than on its relative price, can help reduce the likelihood that you will experience the contrast effect.

In addition, you can use other debiasing strategies , such as slowing down your reasoning process, which will help reduce the degree to which you rely on the flawed intuition that causes you to experience the contrast effect in the first place.

How to use the contrast effect

You can use the contrast effect to your advantage in order to influence people’s thinking in various situations. For example, you could:

Highlight an important button in a design by placing it against a drab background.
Make an expensive product feel reasonably priced by placing it next to a more expensive option.
Minimize the perceived severity of an issue that you cause by comparing it with more serious issues that happened in the past.

Note that using the contrast effect in this manner can be valuable not only when it comes to influencing other people, but also when it comes to influencing your own thoughts.

For example, consider the example of using the contrast effect to minimize the perceived severity of an issue that you caused. You could do this in order to influence the opinion of someone related to the issue, in order to reduce the backlash that you have to deal with, or you could do this to influence yourself, and get yourself to feel less anxious about what you did.

When you use the contrast effect to influence people’s thinking in this manner, there are generally several factors that you should pay attention to, in order to create a powerful contrast:

High relevance. The more related the things you are comparing are to each other, especially in terms of the main trait in question, the more noticeable the contrast between them will be.
A strong connection. The closer the things that you are comparing are to each other, in terms of factors such as space or time, the easier it will be to notice the contrast between them.
A large difference. The more different the things that you are comparing are from each other, especially in terms of the main trait in question, the more noticeable the contrast between them will be.

Keep in mind, however, that these are only general guidelines, and the exact implementation of the contrast effect will vary in different situations.

For example, in some cases, going past a certain point when increasing the difference between the available options might actually decrease the likelihood that people will experience the desired contrast effect. This might happen, for instance, if your preferred product is contrasted with a product that is much, much more expensive, which could cause people to avoid comparing the two, or to assume that the cheaper product must be defective in some way.

Summary and conclusions

The contrast effect is a cognitive bias that distorts our perception of something when we compare it to something else, by enhancing the differences between them.
This comparison can be either explicit or implicit, simultaneous or at separate points in time, and can apply to various traits, ranging from physical qualities, such as color and taste, to more abstract qualities, such as price and attractiveness.
For example, the contrast effect can make a sweet drink taste bland if you drink it immediately after drinking something sweeter, or it can make an overpriced product feel relatively cheap if it’s displayed next to a more expensive product.
To reduce the impact that the contrast effect has on you, you can increase the distance between the available options (in terms of factors such as time or space), add more options into the mix, explain why the comparison in question is irrelevant, or use general debiasing strategies.
You can use the contrast effect intentionally, to influence other people’s thinking, as well as your own, such as in cases where you try to reduce the apparent severity of a mistake that you made, by contrasting it with issues caused by others; if you do this, try to make sure that the things being contrasted are related to each other, easy to compare, and noticeably different.

Literary Criticism: Comparing/Contrasting Works, Characters, or Authors

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1. What is Literary Criticism
Critical Literary Lenses
Literary Elements
Comparing/Contrasting Works, Characters, or Authors
3. Find Literary Criticism
4. Write Your Paper
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Comparing/Contrasting Literary Works, Characters, or Authors

Comparing literary works.

Consider which works you want to compare/contrast.
You could make a list of themes from each work and compare them side by side.
Free writing is also a great way to get your ideas on paper.
Spend time brainstorming- those who explore their ideas often have better essays in the end.
Try to determine the central theme of the work you are considering.
Look for a second work that has a similar theme

Common Themes

Good vs. Evil
Coming of Age
War and its perils
Individual vs. Society
Heroism

These are only some of the themes out there. You can explore many other options for your paper!

Questions to Ask

What is the overall message of the work?
Does the main character evolve as the story progresses?
What was the main conflict in the work?
Is the work trying to convey a message about society?
How do symbols tie into or help to develop the theme?

Character Analysis

Select two characters you would like to analyze.
Reread text and focus in on these characters, taking notes as you go.
Make a list of traits for each character and compare/contrast them side by side.
What important traits do the characters possess?
Is the character a main protagonist or antagonist?
Look at the characters actions- how can they be interpreted?
How does the character interact with others?
How does the character interact with the world they live in?
Do you see changes in the character as the plot progresses?

Author Analysis

You can also focus your compare/contrast criticism on two authors.
Reread the authors works you will be critiquing
Take notes about the authors as you read
What does the text say about the Author?
What kind of message is the Author trying to convey to their audience?
Does the author's life and background effect the themes of their works?
Do historical events influence the authors?
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COLT Department of Comparative Literature

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What is Comparative Literature

Comparative Literature is trans-national, trans-medial, and transcultural.

It is a discipline built on pursuing connections—connections between different aesthetic forms, cultural traditions, and ideas. Tracing those connections wherever they lead is what we mean by “comparison,” whether we are following a theme across national and linguistic borders, studying filmic adaptations of literary texts, or inquiring into the places where disciplines intersect.

The “literature” in Comparative Literature refers both to literature as it is traditionally conceived—as fiction, drama, poetry, and literary nonfiction—and also to visual culture and cultural production more broadly.

But fundamentally the discipline of Comparative Literature is also a practice, a habit of learning, a way of studying literature, film and culture without arbitrarily stopping at national or linguistic borders. We acknowledge that the world is interconnected. When we follow ideas across borders we assume, not that the world should come to us, cater to us, or be translated into our language, but rather that it is our responsibility to explore the world, to seek to understand cultures on their own terms, to find commonalities and respect differences.

A language requirement that asks students to begin the journey toward fluency in more than one language marks this fundamental value. We take the steps we can to read and view cultural texts in their original languages; when we cannot, we pay careful attention to what is gained and lost in translation.

Comparative Literature is both an individualized program of study with a high degree of flexibility and a strong cohort of faculty and students with shared interests and values.

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How to Write Comparative Essays in Literature

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What Are the Essential Parts of a College Essay?

A comparative essay is a writing task that requires you to compare two or more items. You may be asked to compare two or more literary works, theories, arguments or historical events. In literature, a comparative essay typically asks you to write an essay comparing two works by the same writer. For example, you may be asked to write a comparative essay comparing two plays written by William Shakespeare.

Although an essay may simply state to compare two literary texts, the assumption is that you should contrast the texts as well. In other words, your comparative essay should not only compare but also contrast the literary texts, it should address the similarities and differences found within the texts.

Identify the Basis for Comparison

In writing your comparative essay, you should first identify the basis for the comparison. The basis of comparison allows you to look for the similarities and differences between the two texts. You might be provided with an essay question or you might have to come up with your own topic. In either case you need to begin by identifying the basis for your comparison. For example, an essay question might ask you to compare the representation of women in Jane Austen's “Sense and Sensibility” and in Ernest Hemingway's “For Whom the Bell Tolls.” In this example, the basis for comparison is the representation of women. If the directions only ask you to compare two literary works then you will need to develop your own basis for comparison. For example, a basis for comparison may be representations of women or minorities or theme, mood, tension or any other literary element that is appears in both texts.

Develop a List of Similarities and Differences

After you identify your basis for comparison, you should examine the literary texts for similarities and differences. The similarity and differences should focus on the basis of comparison. For example, you might conclude that in “Sense and Sensibility” women appear strong willed and confident, while in “For Whom the Bell Tolls,” women appear weak willed and two-dimensional. You will use these observations, along with your list of similarities and differences, to construct your thesis statement and an outline for your comparative essay.

Develop a Thesis Statement and Structure

Once you have compiled a list of similarities and differences and decided what you want to focus on, you should then develop your thesis statement. A thesis statement is the essay’s main argument, and it should reflect the relative significance of each similarity and difference. A good thesis statement will typically include both similarities and differences and take a certain position about which is more important. The structure of your comparative paper should consist of an introductory paragraph, with a thesis statement at the end, a number of supporting paragraphs and a conclusion. The purpose of the supporting paragraphs is to support your thesis statement. You may group them as you say fit. For instance, you might discuss one literary work at a time or focus first on the similarities between the works and then on the differences. Always end your essay with a concluding paragraph that summarizes the information in the essay.

University of Toronto: The Comparative Essay; Vikki Visvis and Jerry Plotnick

Kate Prudchenko has been a writer and editor for five years, publishing peer-reviewed articles, essays, and book chapters in a variety of publications including Immersive Environments: Future Trends in Education and Contemporary Literary Review India. She has a BA and MS in Mathematics, MA in English/Writing, and is completing a PhD in Education.

What Are the Main Points Used to Write a Comparison Essay?

Compare & contrast essay structure, difference between linear note-taking & mind mapping, how to write an essay comparing two movies, how to write the intro paragraph of a literary elements essay, organizing principles for writing an essay, how to write a unified essay, how to start an introduction when writing an essay about poetry, how to cite in asr style, most popular.

1 What Are the Main Points Used to Write a Comparison Essay?
2 Compare & Contrast Essay Structure
3 Difference Between Linear Note-Taking & Mind Mapping
4 How to Write an Essay Comparing Two Movies

Parallelism

Parallelism Definition

What is parallelism? Here’s a quick and simple definition:

Parallelism is a figure of speech in which two or more elements of a sentence (or series of sentences) have the same grammatical structure. These "parallel" elements can be used to intensify the rhythm of language, or to draw a comparison, emphasize, or elaborate on an idea. The following well-known adage is an example of parallelism: "Give a man a fish, and you feed him for a day. Teach a man to fish, and you feed him for a lifetime." The grammatical structures of the first and second sentences parallel each other.

Some additional key details about parallelism:

Parallelism can be as simple as choosing grammatically similar elements when writing a list, as in "First do X, second do Y, third do Z."
In some cases, parallelism involves the exact repetition of words, but all that is required to fit the definition of parallelism is the repetition of grammatical elements.
Parallelism is a prominent feature of Hebrew and Middle Eastern poetry, and it appears frequently in both the Old and New Testaments of the Bible.

How to Pronounce Parallelism

Here's how to pronounce parallelism: par -uh-lel-iz-em

Parallelism in Grammar vs. in Rhetoric and Literature

The term "parallelism" is used to describe both a figure of speech and a principle in grammar, although its use in each context is slightly different.

Parallelism in Grammar

In grammar, parallelism is the principle that using similar grammatical elements in certain contexts—when making a list, for example—leads to sentences that flow in a more natural way. In the following sets of sentences, the first version is parallel while the second is not. Note how the examples without parallelism are awkward and a little confusing.

In this first set of sentences, the first sentence contains a list of three parallel nouns , while the second combines two nouns with a verb .

Parallelism: Their son loved playing chess , video games , and soccer .
No parallelism: Their son loved chess , video games , and to play soccer .

In the second set of sentences, the first contains parallel adjectives , while the second combines two adjectives with a verb .

Parallelism ( adjectives ): The Bach Sonata was beautiful , moving , and inspiring .
No parallelism: The Bach Sonata was beautiful , moving , and it inspired .

Parallelism in Rhetoric and Literature

In contrast to the strictly grammatical view of parallelism, in rhetoric and literature parallelism can do much more than just create a pleasing and grammatical sentence structure. Writers use parallel grammatical elements within one sentence or, more broadly, between and among different sentences in a paragraph, for effect : to emphasize ideas or themes , suggest connections, or highlight contrasts, all while adding rhythm to the structure of their expression.

Parallelism and Related Figures of Speech

While parallelism is itself a figure of speech, it can also be seen as a kind of "umbrella" category of a number of different figures of speech. Put another way: there are a number of figures of speech that make use of parallelism in specific ways. It's useful to know what these other terms mean, since technically speaking they are specific types of parallelism.

Parallelism and Antithesis

One literary device that often makes use of parallelism is antithesis . In antitheses, two elements of a sentence are placed in contrast to one another. This opposition is clearest when a writer puts the ideas in parallel positions. Neil Armstrong used antithesis with parallelism when he first stepped onto the surface of the moon in 1969, using the parallel structure of the two halves of his sentence to highlight the contrast between his "small step" and the "giant leap" that this step represented in the history of humanity.

That's one small step for a man, one giant leap for mankind.

Parallelism and Anaphora

Another specific type of parallelism is anaphora . This figure of speech involves the repetition of at least one word at the beginning of successive clauses or phrases. In one of Winston Churchill's most famous speeches during World War II, he makes stirring use of anaphora :

.... We shall fight in France, we shall fight on the seas and oceans, we shall fight with growing confidence and growing strength in the air, we shall defend our island, whatever the cost may be. We shall fight on the beaches, we shall fight on the landing grounds, we shall fight in the fields and in the streets, we shall fight in the hills; we shall never surrender...

Note that there are also other uses of parallelism in this excerpt of Churchill's speech that do not fall into the category of anaphora. The different locations that Churchill names ("on the beaches...on the landing grounds...in the fields and in the streets...in the hills") create parallelism through their grammatical similarity.

Parallelism and Asyndeton

In asyndeton , a conjunction (such as "and") is omitted between parts of a sentence to create a certain rhythm. Often, this is made possible by parallelism, which helps the reader to interpret the sentence's meaning even when it is not (technically) grammatically correct. In Julius Caesar's famous boast to the Senate after his victory at the Battle of Zela, he makes use of asyndeton because he omits the word "and" before the final clause.

Veni, vidi, vici : I came, I saw, I conquered.

Technically this omission of "and" makes the sentence an example of "comma splicing," which is a grammatical no-no, but the parallelism allows the meaning to come through and creates a pleasing rhythm.

Parallelism and Epistrophe

Epistrophe is the opposite of anaphora . Instead of repeated word(s) at the beginning of successive phrases, epistrophe involves repeating words at the end of successive phrases. Abraham Lincoln employed epistrophe when he declared in his Gettysburg Address that the Union was fighting to defend a government "of the people , by the people , for the people ." Again, this is an example of parallelism as well as epistrophe, since epistrophe is just a specific type of parallelism.

Parallelism Examples

Parallelism examples in literature.

Parallelism occurs frequently in poetry and prose, from ancient Hebrew poetry to contemporary fiction.

Parallelism in Psalms of the Old Testament

Parallelism is found throughout both the Old and New Testaments of the Christian Bible. In this pair of verses from Psalm 24, there are two examples of what biblical scholars call synonymous parallelism , meaning that the idea of the first clause is repeated and rephrased with a parallel grammatical structure in the second clause to emphasize or amplify the point.

The earth is the LORD's and everything in it , the world, and all who live in it ; for he founded it upon the seas and established it upon the waters .

Parallelism in Shakespeare's Julius Caesar

In Shakespeare's Julius Caesar , Mark Antony is given the opportunity to speak at the funeral of his recently assassinated friend, Caesar. He uses this chance to incite a riot in the hopes of winning back control of the Senate from the conspirators who assassinated Caesar in the first place.

Friends, Romans, countrymen , lend me your ears; I come to bury Caesar , not to praise him . The evil that men do lives after them ; The good is oft interred with their bones ...

The first use of parallelism in Antony's speech comes in the list of nouns with which he calls the crowd to attention, naming their reasons to be loyal listeners as friends and patriotic citizens. Antony then uses parallelism again (with antithesis ) to state his intended purpose by contrasting the verbs "to bury" and "to praise." The third instance of parallelism is also an example of antithesis.

Parallelism in Ernest Hemingway's A Farewell to Arms

In this passage from A Farewell to Arms , Hemingway uses repetition and parallelism to create a rhythm that gives his simple style a precise and powerful effect. This repetition continues the matter-of-fact tone in which the narrator is describing the events of the war. This particular parallelism could also be called an example of epistrophe because its repetition occurs at the end of successive clauses.

Up the river the mountains had not been taken ; none of the mountains beyond the river had been taken . That was all left for next year.

Parallelism in Henry Wadsworth Longfellow's "Paul Revere's Ride"

In this famous poem, Longfellow chronicles the ride of Paul Revere on his way to warn colonists of the attacking British soldiers. The first two instances of parallelism are simple repetitions of grammatical elements— first the repetition of a verb phrase, and then a series of adjectives . The third instance is also an example of antithesis (as well as anaphora , with the repetition of "now"). This third parallelism also sets the scene with the striking imagery of the horse's hooves.

He has left the village and mounted the steep And beneath him, tranquil and broad and deep , Is the Mystic, meeting the ocean tides; And under the alders, that skirt its edge, Now soft on the sand , now loud on the ledge , Is heard the tramp of his steed as he rides.

Parallelism in Jhumpa Lahiri's The Namesake

In this short excerpt from Jhumpa Lahiri's The Namesake , there are several examples of parallelism used to create rhythm within a sentence while elaborating on an idea. Here you can see how even without using the more elaborate versions of parallelism (anaphora, antithesis, asyndeton, etc.), the simple choice to use elements that are grammatically parallel within a sentence helps these sentences to flow effectively.

Without a single grandparent or parent or uncle or aunt at her side, the baby's birth, like most everything else in America, feels somehow haphazard , only half true . As she strokes and suckles and studies her son, she can't help but pity him. She has never known of a person entering the world so alone , so deprived .

Parallelism Examples in Rhetoric

Parallelism can add pleasing rhythm to speech that makes it seem more eloquent, can help to highlight or emphasize ideas, and through its use of repetition can make a speech more persuasive. No wonder politicians and other speech-makers use it all the time.

Parallelism in President John F. Kennedy's Inaugural Address

In his first speech to the American public as President, JFK explicitly sent a message to the nations of the world that the United States would undergo any difficulty to defend liberty around the world. In just this one sentence, he uses parallelism in a few places, two of which could also be classified as antitheses .

Let every nation know, whether it wishes us well or ill , that we shall pay any price , bear any burden , meet any hardship , support any friend , oppose any foe to assure the survival and the success of liberty.

Parallelism in President George W. Bush's Address to the Nation on Terrorism (September 20th, 2001).

In this speech, delivered just over a week after the attacks of September 11th, President Bush declared a "war on terror." There are three instances of parallelism in just these two sentences, with the first also being an example of anaphora , since it involves a repetition of words at the beginning of a phrase. The second and third uses of parallelism are lists whose parallel structures create rhythm and establishes a link between the many different responses to the terrorist attack.

We have seen the state of our Union in the endurance of rescuers, working past exhaustion. We've seen the unfurling of flags , the lighting of candles , the giving of blood , the saying of prayers —in English , Hebrew , and Arabic .

Parallelism Examples in Song

Parallelism is a common feature of many song traditions. Songwriters use parallelism to create rhythm and link ideas together.

Parallelism in "The House of the Rising Sun"

In this traditional folk song from the American South, made famous by The Animals, parallelism paints a picture of the singer's background, while contrasting his mother's honest profession (tailor) with his father's dishonest one (gamblin' man):

My mother was a tailor She sewed my new blue jeans My father was a gamblin' man Down in New Orleans.

Parallelism in "Days Like This" by Van Morrison

In this song , Van Morrison uses several forms of parallelism, including both anaphora and epistrophe —which, when used together, create symploce . This example makes the rhythmic potential of parallelism clear, and shows its usefulness in song-writing.

When it's not always raining there'll be days like this When there's no one complaining there'll be days like this When everything falls into place like the flick of a switch Well mama told me there'll be days like this .

Why Do Writers Use Parallelism?

Parallelism is an important tool at any writer's disposal, and can be used for a variety of purposes:

To emphasize the relationship between two or more sentences in a paragraph, or two or more ideas within a single sentence.
To compare or contrast two different things or ideas.
To create a stronger sense of rhythm in a text.
To drive home a point through repetition.
To elaborate on an idea.

Notice how even the bulleted list above is an example of parallelism. It's easy to read in part because the grammatical structure of each line is identical, beginning with an infinitive ("to" + verb). Parallelism is everywhere because it's one of the rules of grammar that makes ideas (both simple and complex) easier to understand.

Other Helpful Parallelism Resources

Sound bites from history: This website collects audio samples from speeches in American history, so that you can hear parallelism in action.
University Webpage: This professor's page includes some helpful breakdowns of sentence structure and grammatically correct examples of parallelism.
The Wikipedia Entry on Parallelism: A useful rundown of parallelism with relevant examples from throughout world history.

The printed PDF version of the LitCharts literary term guide on Parallelism

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Connotation
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Comparative Literature With Examples

Comparisons are about aspects of texts of different cultures. The main focus of the Comparisons has a specific time, type of title and theme, or it can be in the text itself such as language and structure. We all live in a modern world where the texts, languages, and cultures meet which is the main reason; we have to expand our scope to look at the world.

Importance of Comparative Literature

Comparative texts allow you to read a variety of topics around the world and improve your perspective by analyzing and comparing themes. These can be religious, social, or political. Overall, it develops a broader perspective on the world’s literature and its roots. For those who are planning to study this type of literature, here are some reasons why they should continue:

1. For Comparing Variety of Written Pieces

Comparing the Scriptures is more than comparing one book with another. You also learn about the different literary styles that exist in two different countries and cultures and how they look at books. By analyzing the differences, we also learn about the similarity of the pieces of writing. By reading Comparison Texts, you will learn about works from countries like Egypt, Russia, South Africa, Europe, and more.

2. You get to work in another language

If you know many languages, you can read and write text in the first language. With this, you can take your skills to the next level and begin translating texts into different languages. Even if you are new to learning a language, make an effort to learn it well as this can help you in your work and you are very good at Comparative Literature.

3. Comparative Lit Challenges Your Viewpoint

Comp Lit not only analyzes as it also helps to develop your perspective on the challenges of writing. It allows you to delve deeper into topics such as colonialism, capitalism, and more and decide whether you agree or disagree with this view. It moves you to think about why there is no such thing as a global bookstore and if there are any opportunities. The ideas and methods you follow will allow you to create a completely different perspective.

4. You get to learn from academicians who are involved in research

For newbies, it is a great opportunity to learn from people who are already researching topics and provide expert opinion on discussion topics. With regular workshops and conferences, you will delve deeper into the world of comparative literature.

Comparative texts are an exploratory topic and are at a very high level as you need to develop an idea in two different ways of literature. Over time, you begin to think about the different themes that exist around the world and why they are the same and different.

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Title: causal models for longitudinal and panel data: a survey.

Abstract: This survey discusses the recent causal panel data literature. This recent literature has focused on credibly estimating causal effects of binary interventions in settings with longitudinal data, with an emphasis on practical advice for empirical researchers. It pays particular attention to heterogeneity in the causal effects, often in situations where few units are treated. The literature has extended earlier work on difference-in-differences or two-way-fixed-effect estimators and more generally incorporated factor models or interactive fixed effects. It has also developed novel methods using synthetic control approaches.

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Published: 25 November 2023

The effect of animal-assisted interventions on the course of neurological diseases: a systematic review

Veronika Mittly ORCID: orcid.org/0000-0003-1670-2501 1 , 2 ,
Cecilia Farkas-Kirov 3 ,
Ágnes Zana ORCID: orcid.org/0000-0001-8569-1776 1 ,
Kata Szabó 4 ,
Veronika Ónodi-Szabó 5 &
György Purebl ORCID: orcid.org/0000-0002-9750-2001 1

Systematic Reviews volume 12 , Article number: 224 ( 2023 ) Cite this article

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In our experience, working with a therapy animal strengthens endurance, maintains motivation, provides a sense of achievement, and boosts overall mental resilience. The aims of this work were to summarize the results of quantitative research on the possibilities of animal-assisted intervention (AAI) among people with neurodegenerative and cerebrovascular diseases and to attempt to assess the effects of animal-assisted interventions in an objective manner and to find supporting evidence based on published literature.

Our target groups are people diagnosed with Parkinson’s disease, multiple sclerosis, or stroke. A systematic search of relevant articles was conducted by two independent researchers in April 2021 and August 2023. The search for studies was conducted using PubMed, Google Scholar, Web of Science, Scopus, and Ovid databases, specifying keywords and search criteria. The qualitative evaluation of the research reports was conducted by four independent researchers, using the Newcastle–Ottawa Quality Assessment Form.

According to the scientific criteria and based on the Newcastle–Ottawa Quality Assessment Form, thirteen publications met the search criteria, out of which 9 publications were rated good and 4 publications were rated poor. Evaluating the publications we found evidence that AAI had a measurable impact on participants, as their physical and mental health status significantly improved; however, mental health improvement was more prominent.

Conclusions

By developing evidence-based research methodology and standardized research settings, AAI could be measured effectively as part of health care practice. This would bring significant benefits to the rehabilitation of patients in need.

Systematic review registration

PROSPERO CRD42021255776.

Peer Review reports

The therapeutic use of animals goes back several decades. Animal-assisted interventions in healthcare institutions and among patients are widespread worldwide [ 1 , 2 ]. Clinicians and rehabilitation professionals consider the involvement of therapy animals as an effective complementary therapy option, which can greatly assist doctors and therapists in encouraging patients to achieve therapeutic goals.

Approximately 40% of those in need of rehabilitation have a neurological problem underlying their functional impairment. According to a study, more than half of those affected by a cerebrovascular event develop speech and/or motor function impairment, and only about one third of them are able to resume their previous job. Due to the nervous system’s plasticity, the regular practice of specific tasks and daily skill development can help restore impaired function [ 3 ].

Besides stroke, the effects of animal-assisted interventions have also been examined in many studies in other areas of neurorehabilitation. Dog-assisted therapy carried out with Parkinson’s disease patients has been shown to have a positive effect on motor performance, mood, and quality of sleep [ 4 ]. The introduction of dog-assisted therapy for these patients was recommended by several experts to improve gait and balance and to treat depression, mood disorders, apathy, and anxiety often associated with the disease [ 5 ]. Equine-assisted/dog-assisted therapy has been successfully used with patients with multiple sclerosis. As a result of the rhythmic movement, the torsional and extension motions of the trunk musculature led to a significant reduction in lower limb spasticity and an improved sense of balance. In addition, psychosocial effects of the therapy have also been reported among these patients, who reported that their quality of life improved as a result of animal-assisted therapy [ 6 , 7 ]. Hammer et al. found that animal-assisted therapy had a positive effect on the subjects’ gait, balance, coordination, and muscle strength [ 8 ]. The above is supported by another research study conducted among people with multiple sclerosis. According to this study, quality of life indicators significantly improved among people in the intervention group. Based on their scores on the Berg Balance Scale, their balance and coordination improved, and they became more confident in their movements [ 9 ].

Animal therapy can be implemented in several ways. Animal-assisted intervention is a goal-oriented activity for healing (AAT, animal-assisted therapy) and/or recreation (AAA, animal-assisted activity), which is carried out with animal involvement. In animal-assisted therapy, a trained therapy animal, a trained therapy animal handler, and a professional with expertise in the respective field who knows the individual or group work together to carry out a goal-oriented and personalized therapeutic intervention. In animal-assisted activity, however, only the beneficial effect of the presence of the therapeutic animal is utilized, primarily for recreational purposes and to improve quality of life [ 2 ].

Two issues definitely need to be clarified in connection with AAA and AAT. First, the question of efficacy, i.e., whether the positive clinical experiences that make AATs so popular can actually be measured in terms of clinical effectiveness (i.e., both symptom reduction and improvement in quality of life) and, if so, what the active impact factors of AATs might be. Based on several years of experience in animal-assisted intervention, our research team found animal-assisted intervention to be highly beneficial for the mental and physical well-being of both children and adults. The aim of the present systematic review is to summarize the results of quantitative research on the possibilities of animal-assisted activity or therapy among people with neurodegenerative and cerebrovascular disease. The rationale for this topic is demonstrated by the significant rates of functional impairment that develop and persist as a result of the abovementioned diseases. Our further aim is to provide a scientific approach to the effects of animal-assisted interventions, to objectify them, and—based on a summary of the reviewed studies—to identify evidence.

The target populations of the reviewed literature include people with Parkinson’s disease, multiple sclerosis, and stroke. The rehabilitation methods of these diseases share the common property that AAI is used as a complementary therapy, e.g., in addition to rhythm and music therapy or ergotherapy, and the aim is rehabilitation and improving the patients’ quality of life.

We conducted our search on these three diseases. In the selected literature, only one publication mentions Parkinson’s disease patients and one mentions patients diagnosed with multiple sclerosis without quantifying them. The subjects of the other eleven studies were stroke patients. The literature predominantly presents AAI and related research on people with mental disorders; however, we decided not to include this in the search criteria, so that our focus would be more consistent and clear.

Search strategy

Our review was previously registered at PROSPERO (registration number: CRD42021255776). A systematic search for relevant articles was performed by two independent researchers on 21 April 2021, on 29 April 2021, and was repeated on 29 August 2023. To obtain greater coverage of possible articles for our study we executed the search in multiple databases. Besides Pubmed, we searched an additional four databases: Google Scholar, Web of Science, Ovid, and Scopus. Based on relevant studies in this field, this combination should cover more than 90% of all relevant references [ 10 , 11 ]. These studies were identified using the following terms and boolean operators: ("animal assisted therapy" OR "animal assisted intervention" OR "animal assisted activity" OR "pet therapy" OR "dog assisted" OR "canine assisted" OR "equine assisted" OR hippotherapy) AND (stroke OR "multiple sclerosis" OR Parkinson OR neurodegenerative OR neuromusculoskeletal). The range of year of publication was between 2001 and 2023.

Selecting studies, inclusion, and exclusion criteria

To ensure that selected articles met all the inclusion criteria, title, abstract, and full text of records identified from the search were independently screened for eligibility by two researchers. The following criteria were applied for inclusion in our systematic review:

Studies conducted on animal-assisted intervention

Involving adult patients suffering from stroke, Parkinson’s disease, or multiple sclerosis

In addition to randomized, controlled trials, we also included non-randomized, non-controlled studies, as only a few randomized controlled trials had been conducted in this field and we sought to present as many study designs as possible. Reports on children, publications on assistance or service dogs, case reports, systematic reviews and meta-analyses, and studies conducted on robotic animals were excluded. Discrepancies were resolved through discussion between the two review authors or by seeking advice from a third author. Publications in English were included. Duplicate records in the search results were removed using EndNote Web. Figure 1 shows the PRISMA flow chart of our study’s identification and selection process. An additional file shows the PRISMA checklist of our systematic review (see Additional file 1 ).

PRISMA chart of the study’s identification and selection process

Data extraction

Data extraction from all included studies was completed by four independent authors. The following information was extracted from each eligible article: the first author’s name, year of publication, sample size, targeted diseases, measurement tools and methods (e.g. questionnaires), and follow-up results.

Quality assessment

The quality of each study was evaluated by four independent authors with the Newcastle–Ottawa Quality Assessment Form. This scale is one of the most used methods for assessing the quality of non-randomized studies in systematic reviews and meta-analyses. Its widespread use has led to a shared understanding and acceptance of its criteria and scoring system among researchers and reviewers. The Newcastle–Ottawa Quality Assessment Form provides clear criteria for assessing study quality, making the assessment process more transparent. Being well-structured, the Newcastle–Ottawa Quality Assessment Form provides a well-based framework for evaluating multiple domains of study quality.

We assessed eight items, grouped into three categories:

1. Selection of the study groups

2. Comparability of the groups

3. Outcome of the study

Studies were graded as good quality if they met 6 to 8 criteria, fair quality if they met 5 to 7 criteria, and poor quality if they met 0 or 1 point in the selection category or 0 points in the comparability category or 0 or 1 point in the outcome category.

We decided not to execute a meta-analysis for the following reasons: Although statistical methods are available for quantifying the heterogeneity, there are many qualitative differences in the enrolled studies which limit the interpretation of any comparison among them, independently from any kind of formal quantification. Firstly, these are different neurodegenerative conditions with different pathomechanisms. Secondly, all investigated conditions have significant inherent clinical heterogeneity, characterized by different subtypes and many forms of clinical manifestations which also hinder any comparison. Thirdly, the enrolled studies were not homogenous according to severity, age of onset, symptom lengths, and level of disability. Fourthly, considering treatment, different clinical protocols were administered that cannot be standardized statistically.

All of the abovementioned factors hinder the interpretability of any kind of quantitative statistical approach; therefore, we decided to conduct a stand-alone systematic review without meta-analysis.

Details of the abovementioned 13 articles are presented in Tables 1 and 2 .

The main results of the study and results of our quality assessment are summarized in Table 3 .

Table 4 summarizes the outcomes and their abbreviations used in the research.

In their study, Bunketrop et al. (2017 and 2020) assessed whether multimodal equine-assisted interventions targeting functional deficits and behavioral limitations are effective and whether functional improvement is sustained in the late phase after stroke. According to the evaluation, the proportion of people who observed improvement was higher in the experimental groups, with higher scores in gait ability, balance, and working memory, respectively. The improvements were sustained at 3 months and 6 months, as well [ 17 , 15 ].

A study by Beinotti et al. (2013) investigated the impact of equine-assisted therapy on the quality of life of stroke patients. The functional capacity, physical fitness, and mental health of the subjects significantly improved in each area of the SF-36 questionnaire, compared to the control group [ 13 ].

Beinotti et al. (2010) examined the impact of equine-assisted therapy on the re-learning of gait in hemiparetic stroke patients. Compared to the control group, equine-assisted therapy significantly improved lower limb motor function and balance in the experimental group [ 12 ].

In their study, Berardi et al. (2022) investigated the impact of equine-assisted therapy on activities of daily living, quality of life, mood, balance, and gait in patients with Parkinson’s disease. Equine-assisted therapy resulted in statistically significant improvements in the occupational performance, mood, quality of life, gait, and balance of the participants [ 14 ].

Bunketrop et al. (2019) examined whether therapeutic riding and rhythm and music therapy have an effect on functional mobility in the late phase of stroke. In the equine-assisted therapy group, immediate and sustained improvement was shown in short-term gait ability. The music therapy group showed measurable improvement only at the 6-month measurement. The study confirms the beneficial effects of equine-assisted therapy on gait and functional task performance in the late phase of post-stroke rehabilitation [ 16 ].

Sunwoo et al. (2012) analyzed the effects of therapeutic riding on motor skills in adults with brain disorders. The balance and gait of patients significantly improved as a result of equine-assisted therapy. The study indicates that equine-assisted therapy improves the balance and gait speed of people with chronic brain disorders [ 23 ].

Lee et al . (2014) investigated the effects of equine-assisted therapy on balance and gait among adult stroke patients. In the experimental group, significant improvement was found in balance, gait speed, and gait asymmetry, while in the control group, only gait asymmetry was significantly improved. The research indicates that by improving balance and increasing step length and gait speed, therapeutic riding may reduce the risk of falls overall [ 18 ].

Machová et al. (2019) examined the benefits of dog-assisted therapy as a complementary therapy in the rehabilitation of stroke survivors concerning physiological and psychological status. Compared with the baseline measurements, there was no significant decrease in heart rate and systolic blood pressure in either group at the end of therapy, but there was a significant improvement in the subjective well-being of patients who had received AAT [ 20 ].

In their research study, Peppe et al. (2017) analyzed whether the motor and non-motor symptoms in patients with Parkinson’s disease could be improved in the short term by using equine-assisted therapy. According to the results, all participants in the study showed improvement in motor skills; however, this was not significant. The step length increased, the stance and double stance percentages decreased, and their attention, balance, mood, and quality of life improved in their short-term analysis [ 21 ].

Macauley examined the effectiveness of dog-assisted speech therapy for patients with aphasia and its impact on patient motivation. According to the results, the patients felt that they had made more progress during the AAT sessions and had been more motivated to undergo therapy combined with AAT. The effectiveness of AAT was reflected in subjective measures; the patients perceived the therapy as more enjoyable, they were more motivated, showed a wider range of emotions, and became more open in their communication [ 19 ].

In their study, Rondeau et al. (2010) examined the impact of the therapy dog as a therapeutic method and as a walking aid in the rehabilitation of stroke patients. In the presence of a therapy dog, gait speed and gait pattern improved significantly in all cases. According to their results, practicing with a therapy dog improves these scores of patients significantly more than using other aids [ 22 ].

The study of Palsdottir et al. (2020) aimed to analyze the impact of equine-assisted therapy on the participants’ daily engagement and perceived health and to understand what the interventions might mean for the participants' daily lives. The scores of perceived health were higher among those receiving equine-assisted therapy [ 24 ].

In our study, we attempted to review the available methods for quantification of the effectiveness of AAI, based on published literature. Since AAI is a diverse field, both qualitative and quantitative research methodologies were used in the reviewed publications. Therefore, we considered it necessary to review both evidence-based studies and published methods aiming to measure the effectiveness of AAT.

Main findings

To summarize the original findings of our review, although there are multiple research about AAT and many best practices were published, the quantitative comparison of best practices is not possible because of the lack of standardized methodology and lack of standardized research protocols. As the quality assessment scores of the reviewed studies show there are only a few appropriate research methods in this field. Our original findings suggest that AAT is an emerging adjunctive treatment in the rehabilitation of various disorders, which has gained significant popularity. Future studies with homogenized patients’ groups and standardized methodology are needed to increase the comparability of the studies and therefore provide more robust evidence of the efficacy of AAT. Thus, based on the results, we may conclude that AAI significantly improved both the physical and mental well-being of participants, but the mental improvement was more outstanding. According to the results, the physical rehabilitation achieved by AAI is slower, while psychological coping can be facilitated in the short term by the therapy animal.

In-depth comparison of the reviewed research

Of all the research studies we reviewed, three studies examined the effects of animal-assisted intervention on participants based on how the intervention complementing the usual treatment impacted them (Beinotti 2010, 2013, Machová). In addition, two articles examined the effect of animal-assisted interventions carried out in addition to standard therapy, and the effects of other additional interventions besides standard therapy (Bukentrop 2017, 2019).

This is supported by Palsdottir’s research. In their study, participants spent 30 min with effective equine-assisted therapy once a week, complementing this by patients spending 60 min connecting with each other, attuning to the therapy animal, and preparing for the joint activity (social connection, building bridges). This is an important intervention from both the musculoskeletal and the mental perspectives. From Palsdottir’s research, it is clear that AAI induced significant positive changes in the patients’ mental state. Machová et al. indicated that those patients who received AAT felt better despite showing no significant changes in heart rate or blood pressure. The beneficial effect of AAT on patients' well-being is also demonstrated by the subjective mood ratings on a Likert scale that patients completed before and after the session. By improving the mood of the patients, AAT has an indirect impact on the successful rehabilitation of patients. It encourages proactivity in the treatments they receive, improves their interaction with other therapists, and thus improves their relationship with the whole team providing the treatment (Machová, 2019).

In the studies we reviewed, the use of horse-assisted interventions was over-represented compared to dog-assisted ones; however, the results of the research studies suggest that horses are more likely to assist with physical development, while dogs are more likely to assist with mental and social development. Beinotti, Bunketorp, Lee, and Sunwoo et al. supported the beneficial effects of equine-assisted therapy on balance, gait function, and hand and arm use. However, Peppe’s small sample size study found that a 5-week course of equine-assisted therapy in Parkinson’s patients improved motor skills and also reduced anxiety and apathy among participants. The developmental impact of a dog-assisted intervention is supported by the results of Machova and Macaulay. They found that dog therapy increased motivation, mood, and self-reliance in stroke survivors.

Limitations

Clarity is made difficult by the fact that concepts of AAT are still not applied uniformly, as experts do not refer to exactly the same things by them. Despite this incongruity, we tried to use the terminology related to animal-assisted intervention consistently. Thus, we used the term “dog-assisted therapy” for interventions with dogs and “equine-assisted therapy” for interventions with horses, but the activities carried out in the studies with dogs and horses differ from one study to another.

Another important limitation is the diversity of measurement tools. Physical (gross motor function, fine motor function, and balance) and mental changes (mood, motivation, and well-being) are measured very differently, making it difficult to compare results. From the publications we analyzed, we have identified approximately thirty different scales, such as FAC, Fugl-Meyer Scale, BBS, NIHSS SIS, TUG, Timed 10 m-WT, M-MAS (UAS) for the measurement of physical changes, and STAI, OVal-pd, EQ-VAS/EuroQol-VAS SMBQ for the measurement of mental changes. There are also tools that measure both physical and mental states, such as the MOSF36 SF. There are also measurement tools that we identified in several publications, e.g., TUG, Barthel index, and Timed 10 m-WT.

Also, an important limitation is the disproportionality of studies with different species. In the literature reviewed, equine-assisted therapy is over-represented (3 therapies with dogs, 10 therapies with horses), but we have no information on the number of AAI in the world and the proportion of dog-assisted therapies and equine-assisted therapies, and on how many of these attempts to measure the impact of animal therapy. Our research team could analyze only published papers. It is a well-known fact that in past centuries, in the case of dogs and horses (as opposed to other animals), cooperation with humans was a main selection criterion during the course of breeding, and both species have a long tradition of being involved in tasks and being specifically trained.

The quality of the published research varies widely. In the present review article, we examined thirteen publications with the following results: 9 publications were rated good, and 4 publications were rated poor. One possible reason for this may be the scarcity of available literature on the topic that meets the criteria and the novelty of the research field. Due to the small number of papers published on this topic and meeting our quality criteria, we did not limit the scope of the present review to one group of animals, one disease, or one type of animal-assisted intervention. The low number of quality articles published posed a challenge to our research. On one hand, this paints an incomplete/distorted picture of this form of complementary rehabilitation; on the other hand, it also draws attention to the fact that there have been very few studies of appropriate excellence on this topic. Since this field has been undergoing explosive development, our study calls attention to the fact that many more qualitative research studies are necessary to provide an overview of the subject. Besides the low number of quality publications, the other major limitation was methodological heterogeneity. Although the definitions are provided and there is literature that specifies criteria, e.g., for animal-assisted therapy, on reviewing the research reports we found that these definitions are not used consistently in practice. Furthermore, we could find no information on whether there are comparable forms of quality control measurement in place in different countries, and due to their absence, the use of measurement tools and interventions may differ from one country to another, or even from one research study to another. The length of musculoskeletal and social interventions varies. The interventions range from a few weeks or months to complex programs lasting a year. This makes it difficult to compare the effectiveness of AAIs of varying lengths.

In most studies, AAT was used as an adjuvant to conventional medical therapy, but the studies do not provide clear-cut information on whether patients with similar illness severity were selected in the experimental and control groups. Therefore, as mentioned earlier, quantitative comparison of efficacy has major limitations. Although Parkison’s disease seems to be associated with a higher efficacy of AAT than MS, we cannot draw definite conclusions due to significant confounders such as the great variability of the severity, symptoms, and course of the conditions. Affected brain areas can be very different even in the case of one particular disease, which may have direct effects on psychomotor functions. There are many psychological confounding factors (mood, apathy, level of motivation, locus of contol, etc.) which also affect the response to any intervention. Another important factor is the great variability of the studies and the lack of standardized methodology for measuring efficacy. Future studies with standardized assessment and methodology and more homogenous participants groups considering psychomotor functions, disease severity, and mental health state can be eligible for quantifying efficacy differences.

As interest in AAT has grown rapidly and the number of scientific publications on the subject has increased significantly over the last 15 years, there has been an increasing need for both providers and users to review the state of the art in AAT. An important strength of the paper is that it attempts to investigate the effectiveness of AAT by summarizing highly heterogeneous studies that differ in methodology, quality, and target group. The publication following the 2006 peer-reviewed paper, which met the selection criteria in terms of quality, is from 2010, followed by papers published in 2013 and 2014. The fact that 7 of the publications we analyzed were written in the past 7 years suggests that interest in the topic has increased in recent years, with more and more people using AAI. The number of research studies on AAI is growing, and its literature is expanding at a faster pace. A further strength of our paper is that the approach presented in the review provides a quality framework for the development of methodological features for future research. If the presented framework is followed in future studies, comparability, and evidence-gathering would be much easier.

Implication for practice and research

There are few evidence-based studies available, and their summary is insufficient to draw any far-reaching conclusions; however, we may venture to conclude that AAT is an effective adjuvant treatment for the studied diseases, adding significant value to conventional therapies, particularly for psychiatric symptoms and quality of life, and, in the case of equine-assisted therapy, for movement rehabilitation. Therefore, we need to emphasize the importance of developing a uniform measuring methodology, a larger sample size, and detecting significant changes. In the case of control group studies, it would be important to use simultaneous complementary therapies, such as dog-assisted therapy and art therapy in the two analyzed groups. By developing evidence-based research methodology and standardizing the research setting, the effects of animal-assisted therapy could be effectively measured as part of healthcare practice, which would bring about significant benefits in the rehabilitation of patients in need. Interventions of different lengths could be subject to further research in order to identify the length of intervention that is the most effective, and the systemic change a 12-month intervention can trigger in patients’ lives.

It would be a step forward in quantifiable interventions with measurable impact if professionals used the definitions uniformly. It would also be important for research and interventions to have a regulated professional framework for animal-assisted therapy, within which the professionals have the flexibility to tailor the therapy to the clients’ needs.

In connection with the measurements, the idea may arise that control group studies conducted in health care institutions would be more fit for the purpose. However, given the heterogeneity of the patient group and the pharmacotherapy used, the implementation of this cannot be standardized as of yet. In contrast, biometric measurements could be helpful in measuring the impact of AAI.

We would like to confirm that although this is a difficult area to assess, at the same time, an evidence-based approach is indispensable. Psychometric tools (depression, anxiety) are key in measuring changes in mental health.

Based on the results, we concluded that placing emphasis on strengthening coping skills and improving subjectively experienced quality of life and emotional states is important when using animal-assisted interventions. Therefore, AAI has an indirect positive effect on well-being, which is important not only for the individual, but for society as a whole. In our own experience, the effects of animal-assisted therapy are manifested sooner in psychological and mental factors than in physical fitness, and a few appropriate sessions can already have a positive effect on patients’ motivation, general well-being, and quality of life. However, our experience so far suggests that AAI has an effect on physical fitness as well, mainly in terms of reducing pain and increasing mobility.

Our studies have certainly shown that AAT is an area worth investigating, but one that really needs practice guidelines and standardized research methodology. As the popularity of AAT continues to grow among users, it is very important that providers not only respond to these needs, but do so in a way that is evidence-based and according to appropriate standards. The true place of AAT in patient care can only be accurately determined on the basis of methodological excellence both in research and clinical practice.

Availability of data and materials

All data generated or analyzed during this study are included in this published article.

Abbreviations

Animal-assisted activity

Animal-assisted intervention

Animal-assisted therapy

Apathy evaluation scale

Berg balance scale

BDL balance scale

Client satisfaction questionnaire

EuroQol visual analog scale

Functional ambulation category scale

Gait analysis

Geriatric depression scale

Hamilton depression rating scale

Korean berg balance scale

Korean beck depression inventory

Korean modified barthel index

Letter–number sequencing test

Modified motor assessment scale (according to Uppsala University Hospital)

Medical outcomes study 36-item short-form

National institute of health stroke score

Occupational value assessment

Tinetti performance-oriented mobility assessment

Stroke impact scale

Shirom-melamed burnout questionnaire

State-trait anxiety inventory

Timed 10 metre walk test

Time up and go

Unified parkinson’s disease rating scale III

Western aphasia battery

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We thank all personnel working at Semmelweis University, Institute of Behavioral Sciences, and South-Pest Central Hospital National Institute of Haematology and Infectology, Center for Rehabilitation for their support.

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Veronika Mittly, Cecília Farkas-Kirov, Ágnes Zana, and György Purebl had the idea for this article. All authors contributed to the study conception and design. Material preparation, literature search, and data collection were performed by Veronika Mittly and Cecília Farkas-Kirov. Data analysis was performed by Veronika Mittly, Cecília Farkas-Kirov, Kata Szabó, and Veronika Ónodi-Szabó. The first draft of the manuscript was written by Veronika Mittly, Cecília Farkas-Kirov, and Ágens Zana, and all authors commented on previous versions of the manuscript. György Purebl critically revised the work. All authors read and approved the final manuscript.

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Published: 30 November 2023
Oral cancer

Are e-cigarettes a safer alternative to reduce incidences of oral cancer?

Manveer Singh Chhina 1

Evidence-Based Dentistry ( 2023 ) Cite this article

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Oral medicine

Introduction

The rapid increase in the use of electronic nicotine delivery systems (ENDS), such as e-cigarettes and vape pens, has raised concerns about their potential impact on oral health and the risk of oral cancer. Despite their popularity and claims of being a safer alternative to traditional smoking, there is a lack of conclusive evidence regarding the detrimental effects of vaping. ENDS were initially introduced as a safer option for smokers, attracting both traditional smokers and adolescents due to appealing flavours. These devices use a battery-powered heating element to aerosolise a liquid containing nicotine, flavourings, formaldehyde, glycerol, and heavy metals. However, the variability in product composition and design makes it challenging to establish reliable toxicity profiles. This commentary aims to provide an overview of the existing evidence to inform oral and maxillofacial surgery (OMFS) practitioners about the potential risks associated with vaping on oral health and cancer.

Data sources

Data was extracted from ten recent studies, which included systematic reviews, meta-analyses, literature reviews, cross-sectional analyses, and in-vitro studies.

While e-cigarettes have fewer carcinogens than traditional cigarettes, concerns remain about their potential for DNA damage. Reported oral symptoms related to e-cigarette use include dry mouth, irritation, pain, oral ulcers, nicotine-related conditions, and accidents resulting from device malfunctions. ENDS exposure has been linked to oral health issues like dysbiosis, inflammation, periodontal disease, and alterations in the oral microbiome. In-vitro studies have shown that e-cigarettes can induce DNA damage, oxidative stress, and genotoxicity in oral cells. Although direct causality between e-cigarettes and oral cancer remains unclear, there are case reports of oral cancer in heavy e-cigarette users without other traditional risk factors. Additionally, some ENDS components, such as formaldehyde and acetaldehyde, are known human carcinogens, potentially posing a nasopharyngeal cancer risk. ENDS use may increase chemotherapy resistance and alter immune-related gene expression, potentially facilitating HPV-16 infection. Moreover, there is concern that ENDS use could lead to future tobacco smoking among adolescents. The variability in ENDS products further complicates assessing their oral health effects.

Conclusions

Based on current evidence, ENDS should not be considered ‘safe’. The authors recommend documenting ENDS consumption and emphasise the need for extensive research to better understand their effects on oral cavity tissues. Clinicians should remain vigilant and educate patients about the potential risks associated with vaping to make informed decisions about their oral health.

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Holliday R, McColl E. Vaping and oral health—an update for the dental team—dentistry [Internet]. 2022. Accessed 6 Nov 2023. https://dentistry.co.uk/2022/08/22/vaping-and-oral-health-an-update-for-the-dental-team/ .

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Chhina, M.S. Are e-cigarettes a safer alternative to reduce incidences of oral cancer?. Evid Based Dent (2023). https://doi.org/10.1038/s41432-023-00956-7

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Published: 03 November 2023

The comparison of dispersal rate between invasive and native species varied by plant life form and functional traits

Bo Zhang 1 , 2 ,
Alan Hastings 1 , 3 ,
Edwin D. Grosholz 1 &
Lu Zhai 4

Movement Ecology volume 11 , Article number: 73 ( 2023 ) Cite this article

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A long dispersal distance is widely used to indicate high invasiveness, but it ignores the temporal dimensions of plant invasion. Faster dispersal rates (= distance/time) of invasive species than native ones have been widely used in modeling species invasion and planning control management. However, the comparison of dispersal rate between invasive and native plants, particularly for dispersal on a local or landscape scale, has not been tested with a comprehensive dataset. Moreover, both the effects of plant functional traits on the dispersal rate and variation in the functional-trait effects between invasive and native plants remain elusive. Compiling studies from 30 countries globally, we compared seed dispersal rates (km/year) on a local or landscape scale between 64 observations of invasive and 78 observations of native plants given effects of plant life forms, disturbance levels, and measurement methods. Furthermore, we compared the effects of functional traits on dispersal rate between invasive and native species. We found that: (1) Trait values were similar between the invasive and native plants except for the greater height of woody native plants than woody invasive ones; (2) Compared within the same plant life form, the faster dispersal rates of invasive species were found in herbaceous plants, not in woody plants, and disturbance level and measurement methods did not affect the rate comparison; (3) Plant height and seed length had significant effects on dispersal rates of both invasive and native plants, but the effect of leaf dry matter content (LDMC) was only significant on herbaceous invasive plants. The comparison of dispersal rate between invasive and native plants varied by plant life form. The convergent values but divergent dispersal effects of plant traits between invasive and native species suggest that the trait effects on invasiveness could be better understood by trait association with key factors in invasiveness, e.g., dispersal rate, than the direct trait comparison between invasive and native plants.

Introduction

Understanding mechanisms of species invasions is of fundamental interest to biological conservation [ 48 ], and the understanding can be improved by a comprehensive comparison between invasive and native species, e.g., van Kleunen et al. [ 64 ], Davidson et al. [ 10 ], Broadbent et al. [ 5 ]. For example, previous studies revealed that, compared with native plants, invasive ones had significantly higher values of performance-related traits, including seedling relative growth rate [ 23 ], resource use efficiency [ 27 ], and seed production per seed mass [ 37 ]. Moreover, the comparisons suggest that a strong dispersal ability has been recognized as a fundamental driver of biological invasion [ 4 , 53 ], due to dispersal impacts on species range expansions [ 30 , 34 ]. Previous studies focused more on dispersal distance, for example, Nunez‐Mir et al. [ 47 ] showed that invasive species had longer dispersal distance than native ones. However, dispersal distance ignores the temporal dimension of dispersal, which can significantly affect the dispersal ability conferring invasiveness, i.e., if a species disperses the same distance as another species, but in a shorter time, it has a better dispersal ability [ 51 ]. Therefore, by considering the temporal dimension, dispersal rate (= distance/time) could improve the understanding of invasion mechanisms and be another component of a unified framework for biological invasions [ 2 ]. However, to our knowledge, no studies have comprehensively compared dispersal rates between invasive and native plants across a broad range of species since dispersal is one of the most challenging ecological processes to measure in the field [ 8 ].

Dispersal rate information is critical to understand species distribution, abundance, and population dynamics [ 11 , 18 , 61 ]. For example, an intermediate dispersal rate can significantly increase total population abundance in heterogeneous environments than both low and high dispersal rates [ 73 ], and the difference of dispersal rate between two competing species could alter their coexistence trajectory [ 25 ]. Therefore, dispersal rate, which appears as “diffusion rate” in reaction–diffusion models, is one of the most widely used variables to project invasion dynamics in many mathematical models [ 28 , 45 , 72 ]. For instance, to model spread of an invader, a dispersal rate is one of the most important parameters in “Fisher’s equation” [ 20 ], and dispersal rate-based models are more successful in predicting population spread than life-history-based models [ 26 ]. A failure to incorporate dispersal rate into models of vegetation dynamics greatly compromises their predictive capability, leading to substantial modeling uncertainty [ 40 ]. In mathematical models of species invasion, invasive species have been widely parameterized with faster dispersal rates than native ones, given that invasive species are expanding to new habitats, but native ones tend to be stable in their habitats [ 21 ]. However, the variation in the comparison of dispersal rate between invasive and native species are largely unknown, and the variation may be driven by plant life forms (herbaceous vs. woody plants), disturbance levels (low vs. high disturbance levels), and measurement methods. Without considering these factors, we may get a biased comparison of dispersal rate [ 52 ]. Thus, our study compiled dispersal rate data from previous studies and compared dispersal rate between invasive and native plants, given the potential effects of above-mentioned factors.

Seed dispersal could be related to plant functional traits, including seed size and mass, plant longevity, plant height, and leaf traits. For example, seed mass and plant height are significantly related to maximum dispersal distances of multiple species [ 60 ]. Leaf traits, such as greater leaf dry matter content (LDMC) could reduce leaf N and water content, and further decrease plant palatability [ 15 ]. As a result, leaves with lower LDMC are preferred by herbivores, ultimately leading to increased dispersal rates. Thus, these traits are also expected to relate to dispersal rate. Compared with small seeds, large seeds are preferentially selected by animal dispersers [ 54 ], potentially contributing to their more rapid dispersal [ 57 ]. Given similar seed size, seed mass is often negatively correlated with dispersal rate, since wind-dispersed seeds tend to spread faster with lighter mass [ 66 ]. The above-mentioned expectation is well-supported in a broad range of ecosystem types [ 57 ], but exceptions occur, e.g., Wyse et al. [ 70 ]. Plant longevity shows a negative correlation with the dispersal rate because short-lived plants are likely to have better dispersal capacity [ 17 ]. For leaf traits, higher leaf dry matter contents (LDMC) suggest relatively low nutrient contents that tend to reduce plant palatability and attractiveness to herbivores, leading to lower seed dispersal [ 67 ]. Therefore, these functional traits could be used to predict dynamics of seed dispersal [ 1 ]. More importantly, the potentially divergent values of these dispersal-related traits (i.e., functional dissimilarity) between invasive and native plants may explain their hypothesized differences in dispersal rate. The comparison of these traits between invasive and native plants is expected to contribute to explaining and predicting species invasion from dispersal perspective [ 53 ].

We assembled dispersal rates (km/year) of invasive and native species from published data across a broad range of plant species at a global scale. The species invasiveness (invasive vs. native) was based on specific location based on the data source. Furthermore, we extracted data of different plant functional traits for the species studied from public trait databases. Capitalizing on the data of dispersal rate and plant functional traits of invasive and native plants, we tested two hypotheses: (1) Invasive plants have faster dispersal rates than native ones; (2) Functional traits are different between invasive and native plants and affect dispersal rate.

Dispersal rate data

To identify dispersal rate differences between invasive and native plants, we searched research articles written in English in Google Scholar database from 1980 to 2020 and used the keyword combination: (“invasive”, “exotic”, “non-native”, “alien”, “foreign”, “non-indigenous”) AND (“native”, “indigenous”, “native”, “non-exotic”, “non-alien”, “non-foreign”) AND (“dispersal rate”, “slow dispersal”, “fast dispersal”) AND (“plant”, “grass”, “herb”, “tree”, “shrub”, “forest”) in sections of title, abstract, and keyword. It is important to note that very few references (three found in our search) calculated dispersal rates of both invasive and native plants in similar study areas. Therefore, we conducted searches for dispersal rates of invasive and native plants, independently, and this searching approach has already been used by other studies to compile functional trait data of invasive and native species (e.g., Nunez‐Mir et al. [ 47 ]). Note that we followed standard protocol for conducting systematic reviews [ 41 ] to only include species that are clearly defined as an invasive species in the study location, and exclude species that could be defined as invasive due to their high dispersal rate. Additionally, it is important to be aware that some native species may be invasive elsewhere outside of their native range, potentially confounding results. Based on the searching outputs, we went through the sections of Abstract, Methods, and Results of each article. Finally, we compiled data of 64 observations for invasive plants (39 species, 67% herbaceous and 33% woody), and 78 observations for native plants (74 species, 74% herbaceous and 36% woody), derived from 35 published studies for invasive plants and 10 published studies for native plants (Reference list is included in Additional file 1 ). The recognition of invasive and native species was determined by species descriptions from these studies, i.e., invasive species are those not native and causing threats to local ecosystems, native species are those that have always been parts of the ecosystems where studies were conducted. These published works are from 30 countries covering six continents (except Antarctica).

Given that disturbance is a critical factor in plant dispersal, we classified habitats where dispersal rate was collected in each study into two groups (low vs. high disturbed group). The habitats that are close to areas with high human activities (e.g., farm, dock, wasteland, etc.) or characterized by highly dynamic environments (e.g., coastal dune, pasture, and river) are classified into the high disturbed group. Alternatively, the habitats that are generally under relatively stable environments, such as forest, shrubland, and grassland, are classified into the low disturbed group. The disturbance group was included in the data analysis to consider its effect on the comparison of dispersal rate between invasive and native plants.

Additionally, we hypothesized that the difference in dispersal rate between invasive and native plants could be associated with the measuring protocol. Hence, we documented the protocol of how the dispersal rate was measured for all the available studies. We classified these protocols into two groups: Ground based and non-ground-based data. Some studies used field data (pollen or other ground-based measures) to measure dispersal rate as dividing the distance between the location where a species was recorded on the earliest date and the most distant point where a species was recorded by the residence time [ 9 , 29 ], and measures from these studies are classified as ground-based data. Alternatively, studies that used aerial photographs or microsatellite information were defined as the nonground-based data group. For instance, some studies used a series of aerial photographs and population dynamics data at a fine scale to calculate an invaded area, then dispersal rate was calculated via dividing the square root of the invaded area by residence time [ 43 , 50 ], other studies used microsatellite genotypes of seed arrays to determine the dispersal rate [ 13 ]. To keep the dispersal rate in a consistent and standard unit, we used “km/year” as the unit for all the collected data.

Plant functional trait data

We compiled five functional traits that are relevant to dispersal rate from the Botanical Information and Ecology Network (BIEN) database [ 36 ]. The five traits are whole-plant height (m), leaf dry matter content (LDMC) (mg g −1 ), plant longevity (year), seed mass (mg), and seed length (mm). For each of these traits, we selected values from the same ecoregion with a study area. If not available, we used all observations from the trait database. Then, we calculated mean of the selected values for one species. In addition, we classified the plants studied into two growth forms: woody and herbaceous plants.

Statistical analysis

Comparison of dispersal rate and functional traits between invasive and non- invasive species.

The comparisons were made by linear mixed-effect (LME) models with a phylogenetic relatedness between the species studied, and a phylogenetic tree of these species is shown in the Fig. S1 of the Additional file 2 . Both the dispersal rate and functional traits were used at the natural logarithmic scale, and species was used as a random factor in the analysis. Both two models (with a phylogenetic relatedness between the species studied and a phylogenetic tree of these species) used the plant groups (i.e., invasive vs. native plant) as fixed factors. Fixed factors of the dispersal rate model also consisted of plant life forms (i.e., herbaceous vs. woody species), disturbance groups (i.e., low vs. high disturbance), and measurement methods (i.e., ground vs. non-ground data). The homogeneity of residual variance was examined using the residual plots along with fitted values and fixed predictors of the models. The violations of normality were examined using the normal quantile plots. The above statistical analyses were implemented by the R program (R Core Team 2020), and the models were built by the ‘phyr’ package [ 31 ], and the figures were made by the ‘ggplot2’ package [ 68 ]. All analyses were considered significant at p < 0.05.

Structural equation models

A structural equation model (SEM) was built to compare the direct and indirect effects of the five functional traits on the dispersal rate. The dispersal effects of functional traits were compared between invasive and native species using a multigroup analysis. Correlation paths and their directions were hypothesized from previous studies, including from tree height to dispersal rate [ 6 , 38 , 59 ], LDMC to dispersal rate [ 67 ], seed length and seed mass to dispersal rate [ 12 , 56 , 66 , 69 ]. The partial residuals of dispersal rate from the above LME model were used as standardized dispersal rates to mitigate the confounding effects studied above to focus on the effects of plant traits. The plant height, longevity, seed mass, and seed length were used at the natural logarithmic scale to satisfy the assumptions of normality and linearity. The SEM analysis and multigroup analysis were carried out through the piecewiseSEM package in R [ 33 ]. All analyses were considered significant at p < 0.05.

The comparison of standardized dispersal rate

Our results showed that invasive plants had a significantly faster dispersal rate than native ones ( p < 0.001, z score = − 5.79, Fig. 1 A). However, the comparison of the dispersal rate between the two plant groups varied with plant life forms, i.e., compared with native plants, faster dispersal rates of invasive ones were only observed in herbaceous species ( p < 0.001, z score = 4.98), and not in woody species (Fig. 1 B). Moreover, the comparison of dispersal rate between the two plant groups did not vary with disturbance and measurement methods. There were no significant rate differences between the two levels of disturbance ( p = 0.6, z score = 0.52, Fig. 1 C), but ground-based measures showed higher rates than non-ground measures ( p < 0.001, z score = − 4.92, Fig. 1 D). Summary of Z score and p value of predictors in the linear mixed-effect model are recoded in Table S2 in Additional file 2 .

Partial residual plots showing the dispersal rate comparison by plant groups ( A ), plant life forms ( B ), disturbance groups ( C ), and measurement methods ( D ). Boxplots denote the median (centerline) and interquartile range (box), with upper and bottom whiskers (or error bars) extending to 1.5 × interquartile range measured out from upper and bottom sides of the box, respectively. Statistical significances of the comparisons were denoted by the p values calculated by the linear mixed model. The different letters indicate significant differences ( p < 0.05)

The associations between dispersal rate and functional traits

The structural equation model (SEM) explained 34% variation in the dispersal rate and goodness of fit of the SEM was validated ( p = 0.39, Fisher's C = 12.74, df = 12). Based on the SEM, there are two pathways that were similar between invasive and native plants and had significant correlations with dispersal rate (solid lines in Fig. 2 ): (1) seed length was negatively related to dispersal rate (regression coefficient = − 1.26, p = 0.03, t-statistic = − 2.23, df = 81); (2) plant height was positively related to dispersal rate (regression coefficient = 1.44, p < 0.001, t-statistic = 5.65, df = 81). Note that compared with the non-significant factors, standard errors of the significant ones are smaller relative to their coefficient values, i.e., the ratios between standard error and coefficient value are smaller for significant factors than non-significant ones.

Structural Equation Model assesses the direct and indirect effects of functional traits on standardized dispersal rate (standardized D_rate) among the four plant types: woody invasive, woody native, herbaceous invasive, and herbaceous native plants. The solid lines denote similar effects, but the dashed lines denote significantly different effects among the four plant types. The values on the solid and dashed lines are regression coefficients (or slopes), and the values in the parentheses are standard errors of the regression coefficients. Height: whole plant height (m); LDMC: leaf dry mass per leaf fresh mass (mg g −1 ); Seed length (mm); Seed mass (mg); Plant longevity (year)

Notably, we detected pathways from plant functional traits to dispersal rate that were divergent among the four plant types defined by combinations of plant group (invasive vs. native plants) and growth form (woody vs. herbaceous plants) (dash lines in Fig. 2 ). Compared with the other three plant types, herbaceous invasive plants characterized a significant compound path from longevity to LDMC (regression coefficient = − 0.01, p < 0.001, t-statistic = − 4.79, df = 24), and then to dispersal rate (regression coefficient = − 0.02, p = 0.003, t-statistic = − 3.40, df = 21). Based on product of these two negative coefficients, the compound path suggests positive effect of longevity on dispersal rate.

The comparisons of the functional traits

From the above-mentioned trait and dispersal rate correlation analysis, there are four traits showing significant associations with dispersal rates, including longevity, height, LDMC, and seed length. Here we compared values of these functional traits between the four plant types: woody invasive, woody native, herbaceous invasive, and herbaceous native plants. Within each plant growth form, invasive and native plants show similar trait values except for plant height (Fig. 3 , see p values and z scores of the comparisons in Table S1 in Additional file 2 ). For woody species, native plants had greater height than invasive ones ( p < 0.001, z score = 6.830, Fig. 3 B).

Comparison of A Longevity (year), B Plant height (m); C LDMC: leaf dry mass per leaf fresh mass (mg/g) and D Seed length (mm) among the four plant types. All other variables are as previously defined. The asterisk sign indicates the significant difference between invasive and native plants within a plant life form

Compared within a plant growth form, the faster dispersal rates of invasive species than native ones were found in herbaceous plants, not in woody plants

Our analysis showed that the dispersal rates of invasive plants were generally faster than that of native ones. This result parallels previous studies showing longer dispersal distances of invasive plants than native ones, e.g., Nunez‐Mir et al. [ 47 ]. Therefore, both faster rates and longer distances of seed dispersal facilitate plant invasion over a wider spatial range in a shorter time [ 58 ]. Compared with native plants, the faster dispersal rates of invasive plants further support the classic theory that successful invasive species would have greater dispersal ability to occupy vacant niches [ 16 ]. Notably, compared within a plant life form, the faster rates of invasive species were only found in herbaceous plants, not in woody plants. This result is consistent with that compared with herbaceous plants, woody ones are often poor dispersers, and woody invasion tend to be more related to changes in extrinsic conditions such as climate, fire, grazing, and long-distance dispersal mediated by human than local dispersal studied here [ 14 , 55 ]. Therefore, the difference of dispersal rate between invasive and native woody plants may not be as large as previously expected, suggesting the important role of plant growth form in parameterizing dispersal rates of species invasion in mathematical models. In addition to dispersal rate, maximum dispersal is also significantly related to plant growth form [ 60 ]. Moreover, land disturbance and measurement methods did not affect the rate comparison, but we showed that there were faster rates calculated by ground-based than non-ground-based data (e.g., aerial image measurements). The method-caused difference may result from that small individuals (e.g., seedlings) are difficult to be identified with aerial images or other non-ground-based methods, resulting in underestimates of dispersal rate using non-ground measures. This limit may be overcome by recent advance in remote sensing technology, e.g., application of hyperspectral data to map invasive plants [ 22 ].

The dispersal rates showed divergent and convergent associations with functional traits between invasive and native plants

The SEM analysis revealed both divergent and convergent trait effects on dispersal rates between the two plant groups. The effect of LDMC was divergent between the two plant groups. We found that the pathway from longevity to LDMC to wind dispersal rate was only significant on the invasive plants, but not on native ones. The negative association between LDMC and dispersal rate could result from that greater LDMC could reduce leaf N and water content, and further decrease plant palatability [ 15 ]. Therefore, relatively high LDMC is one of the critical anti-herbivory leaf traits [ 32 , 49 ]. As a result, leaves with lower LDMC are preferred by herbivores, ultimately leading to increased dispersal rates. Notably, we showed that the LDMC effect was only significant in invasive plants. It may be caused by that compared with native plants, invasive ones may have less herbivory pressure in the early stage of invasion due to few specialized herbivores in their new ranges, i.e., the Enemy Release Hypothesis [ 71 ]. Consequently, invasive plants may evolve to allocate resources to growth or reproduction instead of defenses against enemies [ 44 ]. This allocation strategy results in declined LDMC and higher seed production, rendering faster dispersal rates with more attractiveness to generalist herbivores as the invasion is progressing [ 24 ]. Therefore, with the allocation strategy, the significant effect of LDMC may contribute to the faster dispersal rates of invasive plants than native ones. However, the dispersal-rate effects of plant height and seed length were convergent between invasive and native plants. Our study showed the positive effect of plant height on dispersal rate, particularly for wind-based dispersal, which is consistent with another cross-species study [ 62 ]. Meanwhile, mixed height effects on dispersal distance were reported (i.e., positive, negative, and neutral effect) in previous studies reviewed by Schupp et al. [ 57 ]. Shorter species could achieve fast dispersal rate through animals by attaching to their fur when seeds are small, leading to high invasion capability [ 42 ].

The functional traits had convergent values between the invasive and native plants

The values of most function traits (longevity, LDMC, and seed mass), with the significant associations with dispersal rate, were similar between invasive and native plants grouped by plant growth form. The functional similarity is consistent with the results of Nunez‐Mir et al. [ 47 ], showing that these functional traits make minor contributions to the separation of invasive and native plants in a trait space. Therefore, the high functional similarity between invasive and native plants supports the ‘join-the-locals’ hypothesis, i.e., invasive plants share traits with native ones to adapt to local environments [ 35 ]. Note that the trait comparison between invasive and native species vary with specific traits studied, e.g., another pair-wise comparison-based study showed invasive plants have higher values for traits related to performance than native ones [ 64 ].

The invasive and native plants showed convergent values of LDMC but different effects of LDMC on dispersal rate as discussed above, i.e., the negative effects of LDMC on dispersal rate was only significant on invasive plants. Thus, compared with the trait values, the divergent responses to LDMC could be more important to understand the different dispersal rates between invasive and native plants. The specific responses to critical functional trait could inform the prediction of dispersal rate and the related species invasion. Therefore, distinguishing invasive and native species could rely on traits associations with key factors determining invasiveness, e.g., dispersal rate, rather than the direct comparison of traits between invasive and native species [ 7 ].

Conclusions and implications

Taken together, the faster dispersal rates of invasive plants were only found in herbaceous plants, suggesting the comparison of dispersal rate between invasive and native plants varied by plant life form. Moreover, the convergent values but divergent dispersal effects of plant traits between invasive and native species suggest the trait effects on invasiveness could be understood by trait association with key factors in invasiveness, e.g., dispersal rate, rather than the direct trait comparison between invasive and native plants. Our study has important implications for modeling species invasion and invasion control. Our database can be used to calibrate mathematical models of species invasion [ 46 ] and develop a dispersal component in modeling large-scale vegetation dynamics given this component is one of the most undeveloped demographic processes, e.g., in Earth System Models (ESM) [ 39 ]. Notably, the significant associations between dispersal rate and functional traits in our study reveal the potentials of using easily-measured functional traits to predict hardly-measured dispersal rates. Moreover, the dispersal rate database compiled by our study can inform practices of invasion control. For example, field applications of biocontrol agents can use our dataset to determine an appropriate releasing speed of biocontrol agents to catch up with the spreads of invasive species [ 19 ].

When collecting data from previous studies, we noticed some critical issues about dispersal studies. First, there is a lack of studies investigating dispersal of a species in both its native range and new environment where it is invading. For example, our dataset only has one species found in both invasive and native plants. This study gap limits our ability to examine whether an invasive species also maintain high dispersal rates when they are native. Second, there is a need to report specific dispersal agent in dispersal studies because dispersal agent is a critical dispersal factor, potentially confounding other factors on dispersal [ 65 ]. However, the agent information were not available from most studies included in our dataset. Third, our dataset focuses on dispersal at a local or landscape scale (or short-distance dispersal events), and the short-distance dispersal is an important step of establishing invasion after a species arrives at a specific location. However, there is a limited data availability of long-distance dispersal events, describing the dispersal process before the species arrival. The long-distance dispersal of invasive species is increasingly dominated by human-mediated dispersal at a global scale [ 63 ]. The long-distance dispersal may still be informed by the trait-based analysis of the short-distance dispersal in our study. For example, given the climate change impacts, plant functional traits related to drought and heat stress could indicate plant preference during the global horticultural trade which is causing another wave of plant invasions [ 3 ]. Meanwhile, the human-mediated dispersal is affected by a wide range of social, economic, cultural, and environmental factors, which could be analyzed by future studies with the increasing data availability.

Availability of data and materials

Data are provided as private-for-peer review. The material is currently stored at Dryad ( https://datadryad.org/stash/share/WP2pW4QA0ADxIIers-CZaIaifoIs4j_ySHA8U_VXk-Y ), and data will be permanently archived by Dryad if the paper is accepted for publication.

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Acknowledgements

We would like to thank Drs. Daijiang Li and Fiona Tooke for suggestions on phylogenetic analysis and standardizing dispersal rate across forest type, respectively. B.Z. and L.Z. acknowledge financial support from the NSF Mathematical Biology program (2325196). L.Z. also acknowledges the OCAST program (PS21-019), USDA McIntire-Stennis program (OKL03208), and USDA-AMS Acer Program (ACER22000057) for financial support.

AH was supported by NSF DMS Division of Mathematical Sciences (1817124). LZ was supported by the OCAST-Basic Plant Science Research program (PS21-019) and McIntire-Stennis project (OKL0 3208).

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BZ, AH, ED and LZ designed the research, BZ and LZ collected and analyzed the data. BZ and LZ wrote the first draft. All authors contributed to revisions of the manuscript.

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Additional file 1. .

Original data of species dispersal rates and functional traits.

Additional file 2: Fig. S1.

The phylogenetic tree of both the invasive and native species studied. Table S1. The p values and z scores of the trait comparisons between the invasive and non-invasive species within one plant forms, i.e., herbaceous and woody plants. Table S2. Summary of Z score and p value of predictors in the linear mixed-effect model.

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Zhang, B., Hastings, A., Grosholz, E.D. et al. The comparison of dispersal rate between invasive and native species varied by plant life form and functional traits. Mov Ecol 11 , 73 (2023). https://doi.org/10.1186/s40462-023-00424-y

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Interprofessional collaboration in primary care: what effect on patient health? A systematic literature review

Céline Bouton 1 , 2 ,
Manon Journeaux 1 ,
Maud Jourdain 1 , 2 ,
Morgane Angibaud 2 ,
Jean-François Huon 2 , 3 &
Cédric Rat 1 , 2

BMC Primary Care volume 24 , Article number: 253 ( 2023 ) Cite this article

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In a period of change in the organization of primary care, Interprofessional Collaboration (IPC) is presented as one of the solutions to health issues. Although the number of inter-professional interventions grounded in primary care increases in all developed countries, evidence on the effects of these collaborations on patient-centred outcomes is patchy. The objective of our study was to assess the effects of IPC grounded in the primary care setting on patient-centred outcomes.

We conducted a systematic literature review using the PubMed, Embase, PsycINFO and CINAHL databases from 01/01/1995 to 01/03/2021, according to the PRISMA guidelines. Studies reporting the effects of IPC in primary care on patient health outcomes were included. The quality of the studies was assessed using the revised Downs and Black checklist.

Sixty-five articles concerning 61 interventions were analysed. A total of 43 studies were prospective and randomized. Studies were classified into 3 main categories as follows: 1) studies with patients at cardiovascular risk (28 studies)—including diabetes (18 studies) and arterial hypertension (5 studies); 2) studies including elderly and/or polypathological patients (18 studies); and 3) patients with symptoms of mental or physical disorders (15 studies). The number of included patients varied greatly (from 50 to 312,377). The proportion of studies that reported a positive effect of IPC on patient-centred outcomes was as follows: 23 out of the 28 studies including patients at cardiovascular risk, 8 out of the 18 studies of elderly or polypathological patients, and 11 out of the 12 studies of patients with mental or physical disorders.

Conclusions

Evidence suggests that IPC is effective in the management of patients at cardiovascular risk. In elderly or polypathological patients and in patients with mental or physical disorders, the number of studies remains very limited, and the results are heterogeneous. Researchers should be encouraged to perform studies based on comparative designs: it would increase evidence on the positive effect and benefits of IPC on patient variables.

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Introduction

The development of primary care, defined as a model of care that supports first-contact, accessible, continuous, comprehensive and coordinated person-focused care, is a global priority [ 1 ]. Studies have already shown that most patients are treated in a primary care setting [ 2 , 3 ]. Most patients suffering from common diseases such as hypertension, diabetes, chronic obstructive pulmonary disease and asthma only consult a primary care provider [ 4 ]. The ageing of populations, the growing importance of chronic pathologies, the international shortage in the health care workforce [ 5 ], and the growing complexity of care pathways call for development of new modalities of practice in primary care.

Functioning in a primary care team, based on Interprofessional Collaboration (IPC), is widely supported by the health authorities in France [ 6 ], similar to existing models in several countries [ 7 ]. IPC is defined as several health workers from different professional backgrounds providing comprehensive services by working with patients, their families, and other caregivers [ 8 ]. This definition can be supplemented by the need for contact, negotiation and interaction among health care professionals. As this concept is recent and vast, several terms have been used, but the term IPC is the most currently used [ 9 ]. Part of these IPC teams regroup professionals in the same practice. Many practices work as a team of GP's, nurses (including Advanced Nurse Practitioners), paramedics (including Advanced Clinical Practitioners), clinical pharmacists, physiotherapists, physician associates and others. In this model, an integrated and collaborative approach to patient care has been developed. The literature on this subject shows a recent emulation with numerous articles in many journals [ 1 , 7 , 8 , 9 , 10 , 11 ]. Several authors have reported that working as a team is a source of satisfaction among professionals [ 7 , 10 ]. A 2018 literature review reported how primary care teams were formed [ 11 ], but it did not report any information on the effect of these organizations on patient-centred outcomes.

Some authors have focused on the team-based approach for specific pathologies for which collaborations largely mobilize specialists and hospital professionals, but these investigations concern secondary rather than primary care services [ 12 , 13 , 14 ]. While a recent literature review [ 15 ] investigated the effect of IPC in a primary care setting on adults with diabetes and/or hypertension, we wanted to further investigate which areas of treatment and primary care team organization had an effect on patient-centred outcomes.

A better understanding and better characterization the composition of IPC teams and the health fields in which this collaboration would be relevant and effective for patients is important for decision-makers and professionals who wish to engage in the evolution of their practice. Which professionals are involved in IPC? For which treatments and illnesses have results been obtained? For which treatments and diseases have we not obtained convincing results?

The objective of this study was to assess the effects of IPC grounded in primary care setting on patients-centred outcomes.

This systematic review was conducted according to the PRISMA guidelines [ 16 ]. We searched for studies published between January 1st, 1995 and March 1st, 2021. To ensure that we found all research articles published by the various health professionals, we chose to increase the number of search engines normally used. The following databases were searched: PubMed, Embase, PsycINFO and CINAHL. Additional articles that were found by hand searching the references were also reviewed. The following research algorithms were used 1) PubMed: ("Intersectoral Collaboration"[Mesh] OR "Cooperative Behavior"[Mesh] OR "Patient Care Team"[Mesh:NoExp]) AND ("Primary Health Care"[Mesh]) AND ("Outcome and Process Assessment, Health Care"[Mesh]); and 2) Embase, PsycINFO and CINAHL: « intersectoral collaboration», « cooperative behaviour», « patient care team» AND « primary health care» AND « outcome and process assessment, health care». First, the titles were reviewed, and then the abstracts and full texts of the selected articles were reviewed independently by two reviewers with the Abstrackr tool [ 17 ]. Any disagreements were resolved by consensus; MJ, MA, and JFH resolved any remaining disagreements.

After reading the full texts, we included the following studies in this analysis:

studies reporting on IPC

studies conducted in the primary care setting, involving primary care providers exclusively

studies involving at least 2 different primary care providers, regardless of the type and level of collaboration (from a simple phone call to a multidisciplinary medical appointment).

The exclusion criteria were as follows:

interventions involving multidisciplinary teams working between primary and secondary care

the absence of a primary endpoint centred on patient health (studies focusing on economic outcomes, manuscripts reporting practices for declarative data only)

the absence of a comparative design with a control group and statistical analysis (studies based on a before-after design involving the follow-up of only one cohort of patients were excluded)

abstracts not respecting the IMRAD structure

manuscripts not accessible in English.

One reviewer (MA) independently extracted data using a prepiloted form and was supervised by a second reviewer (CB), and the following data were collected: study country, pathology(ies) studied, intervention, the number of patients included, design, study duration, main outcome measures, and patient outcomes (selected on the basis of frequency of reporting and clinical relevance). For consistency and clarify of presentation, the results centred on patient outcomes are grouped within 3 categories in the remainder of the manuscript: 1- patients at cardiovascular risk, 2-polypathological and elderly patients, and 3- patients with mental health problems, chronic pain and unexplained complaints.

The quality of the studies was then assessed using the revised Downs and Black Checklist [ 18 ]. The checklist includes 27 items on reporting (10 items), external validity (3 items), internal validity (13 items), and power (1 item). Similar to others studies, the power item was modified regarding whether a power analysis was described (0 = not reported, 1 = reported). The maximum possible score is 28 for randomized studies and 25 for nonrandomized studies. Quality was categorized by using the following Downs and Black score ranges: strong (21-28), moderate (14-20), limited (7-13), and poor (≤ 7) [ 19 ].

Selection and general description of the studies

In total, 3494 titles, 1280 abstracts and 342 full-text papers were screened for eligibility using the inclusion and exclusion criteria (Fig. 1 ). Sixty-five papers were included in the review, comprising 61 interventions [ 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 ].

A large majority of the included studies were from North America (40) or Europe (13). The other studies were from Asia (5), Australia (2), and South America (1). Forty-three studies were prospective and randomized. Four studies were carried out over a period of more than 24 months [ 32 , 34 , 36 , 64 ].

Depending on the studies, the number of patients included varied between 50 and 312,377: 5 studies included more than 5,000 patients, 37 studies included between 200 and 5,000 patients, and 19 studies included fewer than 200 patients.

Constitution of the teams (Table 1 )

Pathologies.

All the studies evaluating the effect of IPC on patients with chronic diseases: patients at cardiovascular risk (28 studies), elderly and/or polypathological patients (18 studies), or patients with mental health problems (12 studies). One study addressed chronic pain related to musculoskeletal disorders [ 78 ], and 2 other studies included patients with medically unexplained complaints [ 77 , 82 ]. We chose to include these studies in the same paragraph and in the same table as patients with mental health difficulties. One study included in the polypathology group evaluated criteria for monitoring comorbidities (warfarin testing compliance, eye care compliance for diabetes, etc.) and cancer screening in the general population (mammograms and occult blood screenings) [ 67 ].

Effect on patient variables

Patients at cardiovascular risk (tables 2 and 3 ).

The 28 studies addressing cardiovascular risk focused particularly on diabetes (18 studies), hypertension (5 studies), overall cardiovascular risk (4 studies), or dyslipidaemia (1 study). The most common primary endpoints were glycated haemoglobin levels (14 studies), blood pressure (14 studies) and LDL-c or total cholesterol levels (9 studies). Three studies had a real morbidity criterion (cardiovascular events) as the primary endpoint, and 3 other studies assessed the number of visits to the emergency department. Fifteen studies described IPC with pharmacists, and 15 described IPC with nurses.

Interventions around cardiovascular pathologies were mainly based on team-based patient education or doctor/pharmacist collaboration (medication review, blood pressure monitoring, frequent contact about treatment by phone, through the patient's file or concertation meetings).

Of the 28 studies focusing on cardiovascular risk, five reported no significant results for their main endpoints. Benedict's study [ 22 ] which included 1960 patients, showed effects on the secondary endpoints, particularly in the short term.

The Heisler [ 34 ] cluster randomized trial focused on physician/pharmacist collaboration. It included 4100 patients but failed to show positive effects on blood pressure at 6 months, and only short-term secondary results showed a 2.4 mmHg improvement in blood pressure related to the intervention. Both groups (control and intervention) showed improvement during the study. The nonrandomized study by Manns [ 38 ] including 150,000 diabetic patients was able to show the effectiveness of the management of diabetic patients in the primary care network, with a reduction in the number of hospital and emergency department visits. Secondary analyses also showed an improvement in ophthalmological follow-up and glycaemic control. Jiao [ 36 , 37 ] also showed an improvement in HbA1c levels and in the occurrence of cardiovascular events (from 2.89% to 1.21%) for the group participating in a diabetes monitoring program. These 2 studies offered network support that included many diabetes professionals: podiatrists, nurses, and dietitians.

Of the 15 studies analysing effects on glycated haemoglobin levels as the primary outcome, 10 reported positive results [ 21 , 28 , 29 , 30 , 31 , 32 , 33 , 36 , 39 , 40 ]. Conversely, 5 studies reported no significant effect on this variable as the primary outcome measure [ 22 , 27 , 35 , 45 , 49 ].

Among the 15 studies analysing effects on blood pressure, 10 reported positive results [ 23 , 26 , 28 , 29 , 31 , 32 , 43 , 46 , 48 , 50 ]. In 3 studies the positive results were only for diastolic blood pressure, with no effect on systolic blood pressure, and one article found an improvement only in systolic pressure without improvement in diastolic blood pressure. Five studies concluded that there was no effect on blood pressure [ 21 , 27 , 34 , 41 , 49 ].

Among the 9 studies analysing an effect on cholesterol levels, 6 reported positive results while 3 concluded that there was no effect [ 21 , 41 , 49 ].

Elderly and/or polypathological patients (Tables 4 and 5 )

The results of studies on the effect of IPC on the care of elderly or polypathological patients are inconsistent. Of the 18 studies included, 10 reported significant positive results, of which 8 were randomized controlled trials. Fifteen of these studies included doctors and nurses, after which pharmacists were the professionals most involved in care. The retrospective study by Riverin [ 64 ] associated nurses with doctors and was based on a population of 312,377 patients. The study did not demonstrate any improvement in the primary outcome measure: hospitalization 3 months after hospital discharge. It showed only a short-term decrease in the number of emergency room visits and deaths (fewer than 4 deaths per 1000 treated) in the group receiving the IPC intervention.

Eight studies did not show the effectiveness of their intervention on their primary outcome measure or variable. Eight randomized trials had documented effects. Three randomized trials [ 52 , 55 , 69 ] showed that the quality of care received by elderly patients was perceived as better when care was provided within the framework of a formalized collaboration among health professionals. The measurement tool in these 3 trials was the Patient Assessment of Chronic Illness Care (PACIC). The same type of result was observed in a study using the Quality of Care for Chronic Disease Management score [ 59 ].

With regard to functional abilities and patient symptoms, the randomized trial by Burns [ 57 ] showed beneficial effects of collaborative outpatient practices on patient variables relating to addiction (IADL, MMSE, maintenance of social activity) or mental health (CES-depression, general well-being, life satisfaction). The effect of IPC on hospital readmissions varied greatly among studies. Sommers et al. [ 66 ] reported a significant decrease in the number of admissions to the hospital or intensive care unit. Riverin et al. reported a decrease in the use of emergency rooms and a decrease in mortality (secondary outcome measure of the study) [ 64 ]. Conversely, some randomized trials concluded that there was no impact on their primary outcome measure [ 51 , 53 , 57 , 60 ].

The only study focusing on cancer screening by mammograms and occult blood screenings in the general population showed better follow-up for patients followed by a health care team [ 67 ].

Patients with symptoms of mental or physical distress (Tables 6 and 7 )

Among the 12 studies addressing mental health, the outcome measures sometimes included depression (10 studies), anxiety (1 study), or posttraumatic stress (1 study). Eleven studies were prospective and randomized, and 2 randomized trials included more than 1200 patients [ 72 , 83 ]. Only one study did not show a significant result on the primary outcome measure [ 83 ], which was the clinical depression score at 2 years.

The evaluation of the effect of IPC treatment on psychological disorders involved various tools: the Hamilton Anxiety and Depression Scale [ 81 ], the Hospital Anxiety and Depression Scale [ 73 ], the Beck Depression Inventory (BDI) [ 70 ], the Symptom checklist-core depression (SCL) [ 71 , 72 , 74 ], the PACIC [ 80 ], the Composite International Diagnostic Validity [ 83 ], the HSCL [ 71 ], and the Patient Health Questionnaire [ 79 ]. Often, the studies did not use validated scores but simply used the rates of cure, recourse to care or therapy use [ 70 , 71 , 72 , 75 , 76 , 84 ].

A positive effect of the IPC intervention on patients with psychological disorders was reported in 10 studies, at least in the short term (6 months). There were no significantly positive results for 2 studies [ 83 , 84 ], including that of Sherbourne, which was the only study to assess depression at 2 years. Chan's study [ 73 ] showed an improvement in the HAD score at 6 months in the intervention group, but this effect was no longer statistically significant at 12 months.

Arean et al., Engel et al. and Aragonès et al. reported an improvement in the SCL-20 score [ 71 , 72 , 74 ]. Four articles reported the effect of collaboration on medication compliance in depressed patients [ 70 , 72 , 75 , 76 ], while Petersen concluded that there was no effect on compliance with these treatments [ 80 ].

Two studies were only interested in medically unexplained symptoms: that of Kolk [ 77 ] did not report a positive effect, and that of Shaefert [ 82 ] only reported an improvement in the "mental health" component of the quality of life score (SF-36) but no improvement in physical symptoms or care utilization at 12 months.

A study on musculoskeletal disorders showed that multiprofessional management involving general practitioners, occupational therapists, physiotherapists and rheumatologists significantly reduced the number of days off work: 63.8 days in the intervention group versus 92.8 days in the control group [ 78 ].

Assessment of study quality

The studies had an average quality score of 17 points (out of 28 points) using the revised Down’s and Black Checklist [min = 9, max = 21]. Eight studies had a high-quality score, 41 had a moderate-quality score, 12 had a limited-quality score (between 9 to 14 points), and no studies had a poor-quality score (< 9).

The studies that assessed the effect of IPC on patient outcomes could be grouped into 3 categories, depending on whether the patients 1) were at cardiovascular risk, 2) were elderly and/or had polypathology, or 3) had mental or physical disorders. One study also aimed to improve prevention care. Our review of the literature did not find any studies that evaluated the effect of IPC on patient outcomes in the following fields: orthopaedics and the musculoskeletal system, cancer care, paediatrics, current infectious diseases, and patient health monitoring. Only one study analysed cancer screening in addition to monitoring comorbidities. The positive effect of IPC on patient outcomes has been widely described in patients at vascular risk. Of 28 studies, only 5 reported no significant effect on their primary outcome measures. For the 2 other categories (elderly and/or polypathological patients, patients with physical or mental disorders), the reported effects varied from one study to another. Among 18 studies that assessed the effect of IPC on the outcomes of elderly or polypathological patients, only 10 studies reported positive effects on the primary outcome measure, and 11 out of 12 reported positive effects in the category of patients with mental disorders. In this last category, 10 studies focused on patients with depressive syndrome. The majority of studies reported clinical improvement in patients. The majority of the proposed interventions relied on 3 main health professionals: general practitioners, pharmacists and nurses. Other professions were less frequently included in the studies.

In general, studies evaluating the effect of IPC are difficult to compare since the interventions are often very different, and the designs and the evaluation criteria vary, making it impossible to conduct a meta-analysis of the data. The number of studies is often very limited: many fields of care have not been the subject of any study. Some pathologies are only approached in a very isolated way, e.g., chronic pain and anxiety disorders. Finally, for the two topics best covered (cardiovascular risk and depressive syndrome), the differences among the studies remain significant and limit the opportunity to aggregate the results. It is notable that the judgement outcomes are also very different. Compliance [ 44 ], patient satisfaction [ 42 ], or improvement in blood pressure or HbA1c levels [ 25 , 29 ] cannot be compared. Finally, even when the studies analysed a bioclinical measure such as HbA1C levels, the authors chose different judgement criteria: the rate of prescription of an examination [ 51 ], the examination completion rate [ 30 , 40 , 49 ], the variation of the result over time or the rate of patients reaching their objective for this measure [ 22 ]. This complicates the comparison of studies. Smith did not show any effectiveness of his intervention on the HbA1c level in diabetic patients (the primary outcome measure) but showed that the proportion of patients who carried out the recommended monitoring examinations had increased [ 45 ]. For the 15 studies evaluating the effect of ICP on arterial hypertension, the diversity of judgement outcomes still remains significant, depending on whether the authors chose to analyse the mean systolic blood pressure value in the intervention arm [ 29 ], the change in systolic blood pressure over one year [ 34 , 43 ], the change in diastolic blood pressure over one year [ 36 ], the proportion of patients with controlled systolic blood pressure (less than 140 mmHg) [ 43 ], the proportion of patients for whom the systolic blood pressure was measured (care procedure indicator) [ 26 ], the proportion of patients for whom an anti-hypertensive treatment dose adjustment was carried out [ 44 ], the evolution of the mean 24-h SBP [ 24 ], or the evolution of the SBP at home [ 48 ].

The clinical impact of the effects observed can also be questioned. For example, the study by Heisler [ 34 ], a large randomized study (4100 patients), showed a reduction of 2.4 mmHg in blood pressure thanks to the help of the pharmacist, which is clinically limited. With regard to depression, one can wonder about the benefit of a 3.6-point reduction in the Hamilton score for patients, even if the result is statistically significant [ 81 ].

As in other studies, we found that GPs, nurses and pharmacists were the most represented professionals in the IPC teams in the primary care setting [ 11 , 85 ].

Several authors have shown that IPC would increases patient use and costs of care [ 86 ]. These indicators of the use and costs of the health care system are important from the perspective of the decision-maker, but they must be interpreted with caution. On the one hand, less use of to the health care system can testify to better individual health with lower morbidity (a reduction in the number of visits to the emergency room for example, or a reduction in the number of hospitalizations) [ 38 , 66 , 87 ]. On the other hand, these indicators can also attest to a positive effect with regard to issues of compliance and improvement of patient health: in many patients with chronic diseases monitored in primary care, the recommendations emphasize the prevention of serious events through the implementation of reinforced medical monitoring, resulting in an increase in the use of health care system by patients. Thus, the increase in the number of consultations with a health care professional may be appropriate during a period of antihypertensive treatment dosage adjustment to allow the achievement of the objectives [ 29 ].

Strengths and limitations

This literature review has several strengths. First, it is the first to identify in a transversal way in which fields the effect of IPC has been analysed and in which fields this effect has been demonstrated. In 2020, Pascucci carried out a literature review and a meta-analysis on the subject, but without restricting its research equation to the primary care setting and only focusing on patients with chronic pathologies [ 88 ]. It concluded that IPC would improve the 3 following cardiovascular outcomes: BP, HbA1c levels, and the number of days of hospitalization in patients undergoing the IPC intervention. Second, our systematic review was based on the PRISMA quality guidelines; the research was carried out in 4 databases. Third, we assume that the focus on studies conducted in a primary care setting, involving primary care providers exclusively, might be a strength, while previous authors focused on the collaborations between primary and secondary care professionals.

This review also has limitations. The formalization of the search equation leading to the selection of studies required tedious work since there is no published search filter to search for articles addressing IPCs. It might be the main limitation of this review. Future work should consist of a specific and sensitive search filter developed by researchers in the field.

It was not possible to perform a bias analysis with the iCROMs [ 89 ] tool because the designs of the studies were too disparate. The quality of the studies was therefore assessed using the revised Downs and Black Checklist [ 18 ].

Effective studies are probably overrepresented compared to ineffective studies due to publication bias [ 90 ]. Similarly, many studies presented significant results but were based on post hoc or subgroup analyses.

The low level of evidence of clinical efficacy may be linked to the low level of internal validity of these studies, which are mainly pragmatic clinical trials [ 91 , 92 ]. These trials are complex and therefore give positive results with greater difficulty.

In our review, the analysis of the differences between the control group and the multiprofessional intervention groups may have been biased by the fact that the primary care teams studied set up collaborative actions based on different concepts, e.g., the use of information technology, the training of health professionals or the therapeutic education of patients. Therefore, it is sometimes impossible to differentiate for these interventions whether the demonstrated effect is linked to the action implemented by a tool or solely by the IPC.

The concrete typology and level of collaboration among professionals differs greatly from one team to another, and this aspect was not the focus of our research. We therefore chose to describe IPC from the perspective of the most common definition and real life practice [ 8 ] without detailing the interactions involved in collaboration or its level. The type and level of interaction within the IPC teams depends on local contexts, dependent on national support for primary care and IPC [ 8 , 9 ]. Reviews have already confirmed that, in this context and in the absence of new work on the subject, it is difficult to find a consensual definition of the typology of IPC [ 9 , 11 ].

Perspective

Primary care research within the framework of IPC must be able to invest in the field of primary prevention and screenings; currently, IPC is underrepresented in the fields of chronic diseases, cancers, vaccination, addictions, etc., as well as some fields mentioned above (locomotor, oncology) that have not benefited or in which little research with a high level of evidence exists. These areas have already been explored and described in the literature, but not with a comparative trial evaluation in the specific field of IPC in primary care. Our focus was quite narrow and doesn’t give a wide picture of the IPC in primary care.

The interventions offered to patients are often well described in the articles, but the description of the type of professionals and their levels of collaboration is often limited. For example, a patient will be able to benefit from an exchange regarding his pathology and treatment with a pharmacist, who will make recommendations that will be discussed with the doctor, but exchanges between health professionals are insufficiently described in terms of the methods, duration, and frequencies of interactions [ 43 ].

Further work should focus on the intensity of IPC and the elements needed to achieve effective IPC. The following organizational elements are necessary: health policies structuring primary care and funding the time needed to work together, networks with local governance, secure and shared IT systems for working together on patient records, trainings for primary care teams to learn how to work together in confidence without losing sight of the patient's objectives [ 93 ].

Some studies, such as that of Benedict in 2018, showed an improvement in the primary outcome measure in the short term (3 or 6 months) without long-term maintenance [ 22 ]. As multiprofessional primary care teams have to deal with an increasing number of patients with chronic pathologies, it would therefore be logical to hope for a long-term effect of these interventions: studies with longer period of follow-up would be needed in this context.

Many studies have shown that IPC can improve the management of patients at cardiovascular risk. Other studies have investigated the effect of IPC in polypathological elderly patients and in patients with mental or physical disorders. For these pathologies, the number of studies remains limited, and the results are heterogeneous. Researchers should be encouraged to perform studies based on comparative designs: it would increase evidence on the positive effect and benefits of IPC on patient variables.

Availability of data and materials

The datasets used and/or analysed during the current study available from the corresponding author on reasonable request.

Abbreviations

Control group

Confidence interval

Diastolic Blood Pression

Hopkins Symptom Checklist score

Hospital Anxiety and Depression Scale

Intervention Group

Interprofessional Collaboration

Low Density Lipoprotein cholesterol

Medication Possession Ratio

Musculoskeletal Disorders

Not Randomized

Not Significant

Prospective

Patient Assessment of Chronic Illness Care

Post traumatic stress disorder

Retrospective

Randomised in Cluster

Systolic Blood Pression

Symptom Checklist-core depression

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Acknowledgements

We thank Solène Girard, Adam Mouhib, Antoine Nogueira, and Louise Rouxel for their help during the data collection. This article is supported by the French network of University Hospitals HUGO (‘Hôpitaux Universitaires du Grand Ouest’).

The study was funded by the French Ministry of Health. The research team members were independent from the Ministry. The funders had no role in the design and conduct of the study; the collection, management, analysis, and interpretation of the data; and the preparation, review, or approval of the manuscript.

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Céline Bouton, Maud Jourdain, Morgane Angibaud, Jean-François Huon & Cédric Rat

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CB and CR were responsible for conducting the systematic review, including the interpretation of the results and the drafting of the full report of the systematic review. MJn, MA, JFH conducted the search and data extraction. MJx contributed to the data analysis and helped to draft the manuscript. All authors read and approved the final manuscript prior submission.

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Revised Downs and Black checklist for assessment of methodological quality.

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Bouton, C., Journeaux, M., Jourdain, M. et al. Interprofessional collaboration in primary care: what effect on patient health? A systematic literature review. BMC Prim. Care 24 , 253 (2023). https://doi.org/10.1186/s12875-023-02189-0

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What is a Comparison?

Use of Comparison in Literature

Examples of Comparison in Literature

Example #1: When I Have Fears (By John Keats)

Example #2: As You Like It (By William Shakespeare)

Example #3: Lolita (By Vladimir Nabokov)

Example #4: The Noiseless Patient Spider (By Walt Whitman)

Example #5: Night Clouds (By Amy Lowell)

Example #6: Animal Farm (By George Orwell)

Example #7: Faerie Queen (By Edmund Spenser)

Function of Comparison

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Comparison Definition

Examples of Comparison in Literature

Example #1: When I Have Fears (By John Keats)

Example #2: As You Like It (By William Shakespeare)

Example #3: Lolita (By Vladimir Nabokov)

Example #4: The Noiseless Patient Spider (By Walt Whitman)

Example #5: Night Clouds (By Amy Lowell)

Example #6: Animal Farm (By George Orwell)

Example #7: Faerie Queen (By Edmund Spenser)

Function of Comparison

Literary Devices

Types of Comparisons

Common Examples of Comparison

Significance of Comparison in Literature

Examples of Comparison in Literature

Test Your Knowledge of Comparison in Literature

10.7 Comparison and Contrast

The Purpose of Comparison and Contrast in Writing

Writing at Work

The Structure of a Comparison and Contrast Essay

Writing a Comparison and Contrast Essay

Key Takeaways

Learning Objectives

What is Comparison and Contrast Writing?

Objective versus Subjective Comparison

Getting started with comparison writing

Structuring comparison writing

Subject-by-Subject (Block) Structure

Introduction

Common Comparison/Contrast Words:

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Example Thesis Statements

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Comparing and Contrasting

The professor says to compare and contrast A and B ...

Sometimes, comparisons are done in the following manner:

How to avoid the "Split Essay": A Second Option for Comparison

What do I do to eliminate the Split?

Comparing and Contrasting

Introduction

Recognizing comparison/contrast in assignments

Using comparison/contrast for all kinds of writing projects

Discovering similarities and differences

Two historical periods or events

Two ideas or theories

Two pieces of writing or art

Deciding what to focus on

Your thesis

Organizing your paper

Subject-by-subject

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The Contrast Effect: When Comparison Enhances Differences

Examples of the contrast effect

Positive and negative contrast effects