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Finding Reason in Rhyme, Nearly Every Time

Happiness, health, love, and money — what else would anyone need?  These most universal of human interests are often the center of common phrases, called aphorisms, that express some general principle about how our world works . . . or so they claim.  For example, we all know that great spenders are bad lenders, and surely, what sobriety conceals, alcohol reveals.  Many people are very familiar with these aphorisms through previous, repeated exposure to them.  One critical feature contributing to the popularity of these phrases is their rhyming pattern.  But how about the phrase an apple a day keeps you pretty healthy? Well, maybe not. The botched rhyme in this last phrase makes us question the truth behind the statement.  This is due to the Rhyme-as-Reason Effect.  This effect is a cognitive bias by which people judge the validity and accuracy of a statement as being more true if the statement rhymes.  So, although the aphorisms are very vague, the use of rhyme as a rhetorical device asserts their claim in a more persuasive way.  

The Rhyme-as-Reason Effect has been demonstrated in many psychological studies.  One such study, conducted by McGlone and Tofighbakhsh, shows how poetic structure can significantly influence our perception of truth in these phrases.  Participants in their study were asked to judge the validity of both rhyming aphorisms and non-rhyming phrases with the same meaning.  For example, phrases like woes unite foes or woes unite enemies were rated by participants for accuracy.  The resulting correlation between rhyming pattern and perceived truth empirically shows how people’s judgment is determined by the aesthetic qualities of the aphorism (McGlone & Tofighbakhsh, 1999). But how?

John Keats

To explain this cognitive bias, the authors refer to the Keats heuristic, named after the famous poet who once asserted “beauty is truth.”  Heuristics are the mental shortcuts that we use to make judgments and decisions, often resulting in biases such as this Rhyme-as-Reason Effect.  Through the Keats heuristic, aesthetic qualities of a phrase are often equated with its validity (McGlone & Tofighbakhsh, 1999).  So because of our natural tendencies to prefer rhyme as a “pleasurable” aesthetic, the distinction between form and content of these phrases is often overlooked.  As a result, rhyme can be treated as reason for aphorisms like these.

In a similar study by the same authors, a second group of participants were explicitly cautioned to base their judgments only on the accuracy of the claim, not the poetic form of the phrases given.  For these trials, the accuracy ratings of the rhyming aphorisms were markedly lower than the control condition that mimicked their original study (McGlone & Tofighbakhsh, 2000).  In analyzing the association between rhyming pattern and perceived truth in this study, McGlone and Tofighbakhsh suggest the fluency heuristic as another possible explanation.  This heuristic suggests that the speed of processing a phrase is correlated with the value attributed to it.  If you are further interested in their findings on the Rhyme-as-Reason Effect, you can read the original and follow-up study online.

When studying the psychological influence of biases such as this, it can also be helpful to analyze activity in the brain.  This is because cortical activity often reflects cognitive function.  Studies involving functional magnetic resonance imaging (fMRI) of the brain reveal interesting data on neural circuitry in response to decisions based on heuristics. This type of imaging analyzes blood flow and oxygen consumption to detect increased activity in specific brain regions.  

The Claustrum

In one fMRI study examining the effects of fluency, researchers observed greater activation in the claustrum, a region associated with the multimodal integration (Volz, Schooler, & von Cramon, 2010).  This means that information from multiple sensory inputs are brought together in the claustrum for further processing and association.  In this region, observation of the rhyming pattern and comprehension of the statement may be processed together.  So what does this mean? As McGlone, Tofighbakhsh, and other theorists suggest, comprehension involves a temporary state in which the information is considered to be true (McGlone & Tofighbakhsh, 1999).  So this implication of truth, processed with the rhyming pattern in the claustrum for greater fluency, may provide the neurological basis for the Rhyme-as-Reason Effect.  

Another cognitive process that profoundly impacts our perception of truth is memory.  This is discussed by Begg, Anas, and Farinacci, whose studies propose recollection and familiarity as the bases of perceived truth in these aphorisms (Begg, Anas, & Farinacci, 1992).  Although these are both features of memory, they act independently and rely upon different types of processing.  Recollection requires an active search of one’s memory, and thus is a type of controlled processing.  Familiarity, on the other hand, is an automatic process resulting from previous exposure that activates memory traces unintentionally.  Controlled processing, as its name implies, requires more intentional effort and conscious awareness than automatic processing.  For these reasons, automatic processing is usually used for easy, familiar cognitive tasks, whereas controlled processing is used for novel, more difficult tasks.  Because these rhyming aphorisms are salient phrases that are heard often, it is logical that they leave many memory traces for both recollection and familiarity.  Further, because memory functions to store important information for use later, the familiarity with and recollection of these phrases may lead us to attribute more credibility or accuracy to their message.  

O.J. Simpson tries on the infamous glove.

So what’s the big deal about a little poetic influence?  Well, the Rhyme-as-Reason Effect can lead to some serious consequences as a result of cognitive bias.  One infamous example of this bias comes from the high-profile court case People of the State of California v. O.J. Simpson.  This trial implicated former NFL player O.J. Simpson in the murder of his ex-wife Nicole Brown and her friend Ron Goldman.  Among the evidence presented in the case was a leather glove found at the scene of the crime.  This glove matched a pair that Brown had purchased for Simpson, and it contained DNA evidence from Brown, Simpson, and Goldman.  When asked to don the leather glove, Simpson was unable to squeeze his hand into it.  This prompted Simpson’s defense lawyer, Johnnie Cochran, to declare several times in his closing argument, “if it doesn’t fit, you must acquit” (Fisher et al., 1997).  Cochran’s repeated use of this rhyming phrase has generated some controversy in the eventual acquittal of Simpson.  Although all forms of evidence are to be considered in the outcome of a trial, the Rhyme-as-Reason Effect suggests that the use of this rhyming pattern in Cochran’s argument could persuade the jury to unconsciously perceive the statement as valid due to cognitive bias (McGlone & Tofighbakhsh, 1999)

To summarize the Rhyme-as-Reason Effect, the critical rhyming patterns seen in phrases like these popular aphorisms afford us enhanced processing fluency, and the speed by which a given statement is processed correlates to the value it is attributed.  Although not every instance of this bias will have consequences as serious as those in the Simpson trial, it is important to know how cognitive biases can influence our judgment and decision making abilities.  You can certainly hope that April showers will bring May flowers, but understanding the Rhyme-as-Reason Effect should surely make you think twice the next time you’re told whoever smelt it, dealt it.


Begg, I. M., Anas, A., & Farinacci, S. (1992). Dissociation of processes in belief: Source recollection, statement familiarity, and the illusion of truth. Journal of Experimental Psychology: General, 121(4), 446.

Fisher, G., Bugliosi, V., Cochran, J. L., Rutten, T., Cooley, A., Bess, C., … & Dershowitz, A. M. (1997). The OJ Simpson Corpus.

McGlone, M. S., & Tofighbakhsh, J. (1999). The Keats heuristic: Rhyme as reason in aphorism interpretation. Poetics, 26(4), 235-244.

McGlone, M. S., & Tofighbakhsh, J. (2000). Birds of a feather flock conjointly (?): Rhyme as reason in aphorisms. Psychological Science, 11(5), 424-428.

Volz, K. G., Schooler, L. J., & von Cramon, D. Y. (2010). It just felt right: The neural correlates of the fluency heuristic. Consciousness and Cognition, 19(3), 829-837.

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