The Keats Heuristic
Make claims rhyme to boost belief and memorability
- Difficulty
- Easy
- Time to result
- ~days to results
- Steps
- 5
- Confidence
- 86%
The Keats Heuristic, from McGlone and Tofighbakhsh (1999), shows that phrases which rhyme are judged more accurate and believable than semantically identical non-rhyming phrases. Given lists of pseudo-proverbs varying only in whether they rhymed, people rated the rhyming versions as truer. Shotton re-ran the study to test memory and found people were about twice as likely to recall the rhyming phrases hours later. Yet almost no one believes rhyme influenced them: only one participant admitted it might have. Despite this proven double benefit, believability plus memorability, rhyme in advertising has collapsed from very common decades ago (don't be vague, ask for Haig; a Mars a day helps you work, rest and play) to around 10 percent today, a gap Shotton attributes to agency incentives favouring complexity over simple, effective tactics.
Origin
From McGlone and Tofighbakhsh's 1999-2000 rhyme-as-reason research, extended with a memorability replication by Richard Shotton.
Core principles
- 01Rhyming claims are judged more believable than non-rhyming ones
- 02Rhyme also makes phrases roughly twice as memorable
- 03People deny rhyme influences them, yet it measurably does
- 04A once-common tactic has been abandoned despite proven power
How to run it
- 1
State the claim plainly
Write the message you want believed and remembered in ordinary, non-rhyming language as a baseline.
- 2
Build a rhyming variant
Rework the phrase so it rhymes while carrying exactly the same meaning, the version people will find more credible.
- 3
Keep the rhyme natural
Ensure the rhyme reads smoothly rather than forced or naff, or it will feel gimmicky and undercut trust.
Pro tip Classic lines like work, rest and play succeed because the rhyme feels effortless.
Watch out A clumsy forced rhyme can look cheap and backfire.
- 4
Deploy where belief and recall matter
Use the rhyming version for slogans and claims that must be both trusted and remembered later.
- 5
Measure, do not ask
Test the effect with A/B comparison rather than asking people if rhyme influenced them, because they will deny it.
In the wild
Participants saw pseudo-proverbs where only rhyme varied, one group a rhyming form, another the same sentiment unrhymed. The rhyming versions were rated significantly more accurate and believable, and in Shotton's replication were remembered roughly twice as often hours later, all while people denied rhyme had swayed them.
→ Rhyme raised both believability and recall for identical content.
Decades of famous campaigns leaned on rhyme: don't be vague, ask for Haig; a Mars a day helps you work, rest and play; Pringles once you pop you can't stop. These lines endured precisely because rhyme made them credible and sticky, yet the tactic has since faded to roughly one in ten ads.
→ Rhyming slogans achieved lasting memorability now largely abandoned.
Common mistakes
Trusting people's self-reports
Audiences insist rhyme does not influence them, so relying on their opinion instead of measured A/B tests hides a real effect.
Forcing an awkward rhyme
A clumsy or naff rhyme reads as gimmicky and can undercut credibility, so the rhyme must feel natural.
Is it for you?
Best for
Slogans, taglines and any short persuasive claim that must be recalled.
Not ideal for
Contexts where rhyme reads as gimmicky or undermines a serious tone.
From the transcript
“phrases that rhyme are more believable”
“we saw people about twice as likely to remember the rhyming phrases as the non-rhymed ones”
From the episode
8 Fascinating Psychological Biases - Richard Shotton - #592
Richard Shotton