Rhyme as Reason Effect

Perception & Judgment

McGlone and Tofighbakhsh (1999)

Are we more likely to find a statement accurate simply because it rhymes?


The “rhyme as reason”, or “Keats heuristic”, effect is a psychological theory named after the English poet’s famous assertion that “beauty is truth, truth is beauty”. Its fundamental idea is that “in certain circumstances, people may rely on a rule of thumb in which the aesthetic qualities of a message are equated with its truth” (McGlone and Tofighbakhsh, 1999). This is in line with Eagly and Chaiken (1993), who described such circumstances as situations in which people lack the knowledge or motivation to critically evaluate a message, and therefore based their agreement on simple heuristics. As quirky as it sounds, this “rhyme as reason” effect seems to be well known by great orators. Thus, McGlone and Tofighbakhsh, 1999 remind us of “defense attorney Johnnie Cochran’s celebrated plea to the jury during the O.J. Simpson trial: ‘If the gloves don’t fit, you must acquit!’”.

Why would people base their judgment of a statement’s truth value on its aesthetic qualities? According to Alter and Oppenheimmer (2009): this is a particular instance of a broader phenomenon: “Human judgment reflects not only the content of our thought but also the metacognitive experience of processing those thoughts. Processing fluency, or the subjective experience of ease with which people process information, is one such metacognitive clue that plays an important role in human judgment.” The reason why phonological fluency (based on sound) might bias our belief in a statement can easily be explained within Kahneman’s (2011) Dual System Theory. According to Kahneman (2011), our automatic system 1 has precisely evolved as an energy-saving mechanism enabling us to make quick judgments by using heuristics, or rules of thumb. As such, it is biased towards information that can be easily processed. More precisely, here, the heuristic rule of thumb is: easy connection (e.g., based on rhyme) between two words = accurate connection between two ideas. Their non-rhyming synonyms could also be strongly connected in our mind through facts and logic. However, this would require the intentional and effortful activation of system 2. Facts and logic strengthen connections between ideas, but the converse rule of thumb that strong connections are based on fact and logic, although unreliable, save us the burden of critical thinking.

Participants & Procedures

60 undergraduates from Lafayette College (Easton, PA, USA.)

The researchers selected 50 proverbs and aphorisms from the Penguin dictionary of aphorisms (Freguson, 1983) and The concise Oxford dictionary of proverbs (Simpson, 1985) meeting the following criteria: they had to rhyme, contain an advisory or descriptive judgment about human behavior (not a value judgment), be unfamiliar, and dissimilar from each other.  The use of unfamiliar sayings was an ingenious way to isolate the independent variable.  Sayings “function primarily as rhetorical devices by asserting a claim in a persuasive way” (McGlone and Tofighbakhsh, 1999). However, this persuasion is not based on logos: proverbs and aphorisms communicate observations or advice about human behavior that are so general that it would be very hard to assess their truth based on their content.  Neither is it based on ethos: unfamiliar sayings do not have an authoritative author, and are not commonly accepted. Thus, the only thing that can make them persuasive is their short and poetic form, including rhyming keywords (“Woes unite foes”). This can be considered a kind of “pathos”, although not an appeal to emotion, but rather to one’s aesthetical sense (kallos).

Thus, for each saying, the researchers created two non-rhyming versions by replacing the first or second rhyming word with a synonym. Based on a pilot study, 30 sets were finally chosen where the original proverb was confirmed not to be known, and to be similar in meaning to its 2 modifications. Participants, who were told that the study investigated the psychological theories implied by common English sayings, were then presented with 3 lists of 10 original and 20 modified proverbs and aphorisms and instructed to rate them on 9-point scales for both comprehensibility and accuracy. Finally, they were asked whether they thought that sayings that rhyme describe human behavior more accurately than those that do not.


As can be seen in the table below, the sayings were rated higher in terms of accuracy in their original rhyming version than in their non-rhyming versions. In addition, this was not due to the fact that their content was more comprehensible. Thus, the researchers concluded that the effect was due to their form, i.e., the presence of absence of rhyming keywords. Interestingly, all 60 participants said that they did not think that sayings that rhyme describe human behavior more accurately than those that do not. Many did not even understand why the researchers asked the question. This is further evidence that the “rhyme as reason” effect is automatic and unconscious.

IA Tip

In line with IB guidelines, we recommend that students only compare two conditions in their experiment. Here, each rhyming saying can simply be compared to its non-rhyming modification. Students may of course use different sayings, and a smaller number of them. They will be able to find innumerable examples in online books such as Mieder (1992), as well as references in Wikipedia. Likewise, students should obtain a single measurable (e.g., a sum or an average) result for each participant in each condition. 

Finally, although comprehensibility ratings and the final question were important in the original study, they can be excluded from its replication and should only be included in students’ discussion of their findings in the “Evaluation” section.


McGlone, M. S., & Tofighbakhsh, J. (2000). Birds of a Feather Flock Conjointly (?): Rhyme as Reason in Aphorisms. Psychological Science, 11, 424–428.