Rhyme as Reason Effect
Easy Definition of the Rhyme as Reason Effect: Don't treat a statement as believable just because it rhymes. If you do, you've been influenced by the Rhyme as Reason Effect.
Geeky Definition of the Rhyme as Reason Effect: The Rhyme As Reason Effect is a cognitive bias that causes a rhyming statement, observation or saying to be judged more accurate than an equally valid non-rhyming one. The Rhyme As Reason Effect occurs because people probably evaluate a statement's truth according to its aesthetic qualities or the ease with which it is processed by the brain (i.e., the fluency heuristic). For example, due to the Rhyme As Reason Effect, "What sobriety conceals, alcohol reveals" is judged often more accurate than "What sobriety conceals, alcohol unmasks".
An Example of the Rhyme as Reason Effect
This ain't my glove, loveOne of the best cited examples of the Rhyme As Reason Effect occurred during the O.J. Simpson murder trial in 1995 when Johnnie Cochran (the American lawyer who defended Simpson) told the jury "If it doesn't fit, you must acquit". Cochran was referring to a pair of gloves (one was bloodied and found at the murder scene; the other was reportedly recovered later from Simpson's house).
When Simpson tried on the gloves, they appeared far too small for him, which allowed Cochran to use his now famous line. Months of testimony followed, but Cochran's rhyming assertion "If it doesn't fit, you must acquit" was considered the turning point of the trial.
The Rhyme As Reason Effect probably works because of the way we evaluate a statement's truth according to its aesthetic qualities or the ease with which it is processed by the brain. However, the Rhyme As Reason Effect may also work because a rhyme suggests a perceived historical wisdom. For example, someone hearing the rhyme "an apple a day keeps the doctor away" might believe that this "fact" has proven so true over such a long time that it has been deliberately written as an easy-to-remember rhyme by some higher authority to help spread the message. People may also believe that such rhyming statements have been well tested, otherwise the rhyme would not have survived the test of time. It is therefore possible that the believability we afford old rhyming statements bleeds across to new ones. After all, why would anyone bother to make something rhyme if it were nonsense?
A Practical Application for the Rhyme As Reason Effect
Make It Rhyme!If you need to convince the public of something, make your statement rhyme. Provided your rhyme asserts something fairly believable, there is a good chance a rhyming version of your statement will be more effective than a non-rhyming one. (Of note, there appears to be a downside to the Rhyme As Reason Effect. If a rhyming statement is slightly suspicious, the rhyme can magnify that suspicion.)
Summary of the Rhyme as Reason Effect: If you think someone has taken a rhyming statement as true without first reviewing a non-rhyming version of the same facts, tell him he may have succumbed to the Rhyme as Reason Effect.