Want to convince someone of something? Make up a rhyme. They may think it's cutesy, but they'll still believe it more readily than if it were stated plainly. At least until they are asked to think about it a little.
Rhymes are easy to remember because they contain their conclusion in their premise. "Red sky at morning, sailors take warning," and "birds of the feather, flock together," and, "leaves of three, let it be," all provide a guide in the first half of the phrase that lets us remember the last half. A couple of experiments show that they do more than jog our memory. They slip past the guard of our rational mind. We are more likely to believe a message when it's put in the form of a rhyme.
It's called the Rhyme as Reason effect, and it's shown to be effective as a persuasion technique and a sales technique. A group of researchers showed volunteers archaic rhyming aphorisms. The aphorisms had to be archaic as people tend to have a heightened positive response to things that are familiar to them. In order to separate believability and familiarity, the sayings had to be new to the listener. One phrase was, "What sobriety conceals, alcohol reveals." The alternate phrase, "What sobriety conceals, alcohol unmasks." The researchers found that people unleashed their inner poets, and their inner poets were traditionalists. The rhyming sayings were rated as more true and trustworthy than the non-rhyming sayings.
Rhyme as Reason extends to commercial slogans. When a group of volunteers was asked to judge between rhyming and non-rhyming sayings, they not only found the rhyming sayings more trustworthy, but more likeable, more original, and more suited to the campaigns they were meant to advertise. We like things that rhyme.
Or, we like them as long was we don't really think about it. In the first experiment, the effects of Rhyme as Reason dissipated quickly when people were simply asked to differentiate between the pleasantness of the rhyme and the meat of the actual saying. Perhaps, with a little thought, the subjects remembered saying a few things they didn't really mean while under the influence of alcohol. Or perhaps they just considered the idea more deeply than they would have if they had just absorbed the rhyme. Whatever the cause, it seems that, if you want people to believe you, break out the rhymes - but don't push it.
[Via Birds of a Feather Flock Conjointly, Rhyme as Reason in Commercial and Social Advertising.]