People have a natural inclination towards phrases that rhyme; in psychology, it’s called the “rhyme-as-reason effect”. Here, global CSO and award-winning strategy leader Leif Stromnes investigates why this effect is so powerful, and how brands can harness it to improve recognition and connection.
On October 3, 1995, more than 150 million Americans watched as O.J. Simpson was acquitted of double murder charges in what became known as the “Trial of the Century”.
The not guilty verdict shocked legal experts who had followed the mountain of DNA evidence, the history of domestic violence, and the timeline that seemed to place Simpson at the scene. How could a jury ignore such compelling physical evidence?
The answer, according to many legal analysts, lay in eight simple words delivered by defence attorney Johnnie Cochran during his closing argument: “If it doesn’t fit, you must acquit”.
Cochran was referring to the infamous moment when Simpson struggled to put on the bloody gloves found at the crime scene. The gloves appeared too small, creating reasonable doubt about Simpson’s guilt. But what made Cochran’s phrase so memorable and persuasive wasn’t just its legal logic, it was the fact that it rhymed.
Those eight words, with their perfect internal rhyme, became the most quoted phrase from the entire trial. They were repeated endlessly on television, in newspapers, and in conversations across America. The rhyme made the argument feel not just memorable, but somehow more true.
This phenomenon has a name in psychology: the “rhyme-as-reason effect”.
First identified by researchers Matthew McGlone and Jessica Tofighbakhsh in 2000, the rhyme-as-reason effect describes our tendency to perceive rhyming statements as more accurate, more credible, and more meaningful than identical non-rhyming statements.
In their study, participants were presented with pairs of sayings that conveyed the same meaning, but only one version rhymed. For example, they compared “What sobriety conceals, alcohol reveals” with “What sobriety conceals, alcohol unmasks”.
The results were striking. Participants consistently rated the rhyming versions as more accurate and insightful, even though the meaning was identical. The rhyme itself was adding a layer of perceived truth.
This wasn’t just about memorability. Even when participants could remember both versions equally well, they still judged the rhyming version as more likely to be true. Something about the rhythmic pattern of rhyming words was triggering our truth-detection mechanisms.
From an evolutionary perspective, this makes sense. For most of human history, important information was passed down through oral tradition. Rhyming made crucial knowledge easier to remember and transmit accurately across generations.
“Red sky at night, sailor’s delight. Red sky at morning, sailors take warning” isn’t just a catchy phrase, it’s a surprisingly accurate weather prediction system that has helped mariners for centuries. The rhyme ensured the wisdom survived.
Our brains learned to associate the cognitive ease of processing rhyming information with reliability and truth. If something was important enough to be preserved in rhyming form, it was probably worth believing.
For marketers and advertisers, the rhyme-as-reason effect represents one of the most underutilised tools in the persuasion toolkit.
In 1981, the Australian Cancer Council faced a daunting challenge: how to convince an entire nation of sun-worshipping beach lovers to protect themselves from skin cancer. Australia had the highest rates of melanoma in the world, yet the cultural association between tanned skin and health ran deep.
Their solution was brilliantly simple: “Slip, Slop, Slap”.
Slip on a shirt. Slop on sunscreen. Slap on a hat.
The campaign featured an animated seagull in a singlet and hat, singing the rhyming jingle while demonstrating sun protection behaviours. Within months, the phrase had become part of the Australian vernacular. Children chanted it in playgrounds. Parents reminded their kids of it before heading to the beach. Television hosts referenced it during weather reports.
The genius wasn’t just in the rhyme, it was in how the rhythmic pattern made complex behaviour change feel simple and inevitable. The three actions flowed together so naturally that following them felt less like medical advice and more like common sense.
Decades later, studies showed that the “Slip, Slop, Slap” campaign was directly responsible for reducing Australia’s skin cancer rates and changing an entire generation’s relationship with sun exposure. The rhyme had literally saved lives by making sun protection feel true and necessary.
Other famous rhyming examples include “Click, Clack, Front and Back,” “Nothing Sucks Like an Electrolux,” “Once You Pop, You Can’t Stop,” and “Beanz Meanz Heinz”.
Despite their effectiveness, rhyming slogans have become unpopular with creative agencies and their clients over time. This is partly because creative tastes have changed, but also because in an age of hyper targeted adverts with personalised headlines, it’s very difficult to make multiple rhyming versions.
This is a great pity.
Part of what makes rhyming advertising so powerful is that it’s collective.
When a line lands and when everyone can chant “Have a break, have a KitKat,” it becomes a kind of social shorthand. It signals shared knowledge, belonging, and even humour.
This is something hyper-personalised, one-to-one advertising can’t replicate.
A private message might be relevant, but a rhyming slogan everyone knows is relational. It builds culture, not just clicks.
The rhyming effect extends beyond simple slogans to brand names themselves. Companies with names like Lean Cuisine, YouTube, FitBit, Chupa Chups and FedEx benefit from increased memorability and perceived credibility compared to non-rhyming alternatives.
Research shows that rhyming brand names are perceived as more trustworthy, more established, and more likely to deliver on their promises. The sonic pattern itself becomes a signal of reliability.
But the rhyme-as-reason effect comes with some caveats for marketers.
The effect works best when the rhyme feels natural and unforced. Consumers can detect when rhymes are artificially constructed, which can backfire by making the message seem gimmicky or insincere.
The rhyme must also support the intended message. A rhyming phrase that contradicts the brand’s positioning or makes unrealistic claims can actually damage credibility when consumers recognise the disconnect.
Most importantly, the effect diminishes when people are explicitly warned about it. Once consumers become aware that they’re being influenced by rhyme rather than reason, the psychological impact weakens.
The most successful applications of rhyme-as-reason in marketing feel effortless and authentic, supporting genuine brand benefits rather than masking weak propositions.
Johnnie Cochran understood this intuitively. His famous phrase worked not just because it rhymed, but because it encapsulated a legitimate legal argument about reasonable doubt. The rhyme amplified a genuine point rather than substituting for one.
Similarly, the Australian Cancer Council’s “Slip, Slop, Slap” succeeded because it made genuinely beneficial health behaviours feel natural and memorable. The rhyme served the message, not the other way around
In a world where consumers are bombarded with thousands of marketing messages daily, the brands that cut through the noise are often those that make their messages feel not just memorable, but somehow more true.
As the O.J. Simpson trial demonstrated, when logic and rhyme collide in the mind, rhyme often wins.
Or put another way, if the words don’t flow, the truth won’t show.
