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The Peak End rule: why more pain means we remember less

In a recent post, I looked at the halo effect and suggested that the familiar saying was quite right: first impressions matter. Humans are very bad at evaluating qualities independently; we can’t help but be influenced by other attributes, which means that initial judgements count for a lot.

Yet what ultimately matters is what we remember. Are first impressions privileged here, as well?

Daniel Kahneman and his colleagues carried out an experiment twenty-five years ago to find out.

The team asked their volunteers to do two things. First, they plunged their hands into a bucket of water, cooled to 14°C, for sixty seconds. Second, after a break, they repeated the experience but then kept their hands in the bucket for another thirty seconds – during which the temperature was raised to 15°C.

Neither was a pleasant experience, but the volunteers said they would prefer to repeat the second rather than the first. A moment’s thought shows that this isn’t rational.

Kahneman’s answer was that the memory of the second was less unpleasant, as it ended less painfully.

He tested this insight a few years later, with colonoscopy patients. I’ll spare you the details, but the final moments were less painful for half of the patients – even though these painful seconds were in addition to the procedure that everyone had experienced.

This time, Kahneman found that the discomfort reported by patients depended on the worst experience and the final experience.

Hence the peak end rule was born: we remember the most intense moment and the last moment.

Does this argue against the idea that first impressions count?

Up to a point: other research has demonstrated a primacy effect: we tend to remember things we encounter early on. Try memorising a list of words: you’re more likely to remember the first few.

A famous study by Solomon Asch, just after WWII, came up with a similar result. You are more likely to judge me positively if I’m described as “intelligent, hard-working, critical, and outspoken” then if I’m said to be “critical, outspoken, hard-working, and intelligent”.

So the primacy effect works alongside the recency effect that features in the peak end rule.

What about the peaks?

Emotion is key to forming memories and surely plays a role here. We find it easier to remember intense, emotional moments and, because recall is more fluid, we have more confidence in such memories (although whether this confidence is justified is quite another matter). 

So what are the implications for public relations?

First, concentrate on the first, last, and intense moments ­– whether part of an event, presentation, or narrative. These are the ones that people will remember and, furthermore, they disproportionately affect overall memories.

Second, this is reinforced by the halo effect: qualities that are evaluated first, or are otherwise privileged, affect the way we score others. Judgements are dependent on each other, with some more dependent than others.

(And, third, hesitate the next time a psychologist asks you to volunteer.)

Justin Jackson MPRCA


Justin is the Founder of Digital Remit (