Psychology in Design— Peak-End Rule

Shah Mohammed
4 min readMar 9, 2017

If you are an Indian, and a cricket fan, what’s the best moment you remember in 2011 world cup? Is M S Dhoni finishing off in style with a monstrous blow over long-on to seal the final? If he scored a single run to finish off, will you remember the moment?

What do you feel when you come out watching superhero action movies like Avengers? What were you discussing immediately after you came out of the theatre? If you were interested in action movies, you would be thinking about the action sequences in the last ten minutes. If you liked the last twenty minutes of the movie, you would rate the movie as good. Why climax plays a massive role in a movie’s success? If the climax is good, you would feel happy when you come out and recommend to others.

“Vennila Kabaddi Kuzhu” was a Tamil movie on Sports(Kabaddi) on the lines of Chak De and Lagaan. This movie just followed the trend of that time — Neither a masala movie nor an off-beat movie. Rural settings — Normal Love story interspersed with comedy — Kabaddi sport — an underdog team — Finally, Underdog team winning the competition — Fine for a normal movie. Then the climax comes — a real shocker, where the hero dies. Most of the audience didn’t expect the result, and they went out with a heavy heart having a tinge of sadness.

Composers, Poets, Novelists, Directors — All try to end on high so that they can leave an impression.

When a speaker ends his speech with a touching or humorous story, you were going to rate the speaker favourable, even though you would not have listened to his entire speech.

By Focussing on End of an event, you can change the perception of a product/service in a consumer’s mind. In psychology, this is called “Peak-End Rule.

From Wikipedia, The peak–end rule is a psychological heuristic in which people judge an experience largely based on how they felt at its peak (i.e., its most intense point) and at its end, rather than based on the total sum or average of every moment of the experience.

The Peak End Rule Says Experiences Are All About The Ending

A 1996 study by Kahneman and Redelmeier assessed patients’ appraisals of uncomfortable colonoscopy or lithotripsy procedures and correlated the remembered experience with real-time findings. They found that patients consistently evaluated the discomfort of the experience based on the intensity of pain at the worst (peak) and final (end) moments. This occurred regardless of length or variation in the intensity of pain within the procedure.

How can we apply this rule in Product Design?

Let’s take an example of Water Bottle which is being used in home and office.

Imagine you want to fill water bottleA from a water dispenser which has slower flow rate. The water level rises very slowly in the bottle, making you restless. Even after half of the bottle is filled, you are still uncomfortable as in the beginning, as you need to wait for the same amount of elapsed time. Your experience curve is almost flat.

Imagine now you use the Bottle B or C or D to fill.

  • In the beginning, the water level may be rising slowly
  • After less than 1/3rd level, you observe water level rises faster
  • Now your focus is on the rising level of water
  • You perceive water filled up faster than Bottle A and your feeling is better than filling water in another bottle. Truth — both bottles took the same time.

E1 and E2 are flat bottles. E2 will provide a better experience than E1.

Assume that following shapes are of Juice Glasses.

When drinking Juice from Glass A, you perceive that you emptied juice faster, feel unsatisfied. The reason — Glass gets emptied faster after you cross halfway mark.

When drinking juice from Glass B, you feel that you took more time to drink juice, perceive the quantity was sufficient. The reason — Juice level decreases slower after crossing the halfway mark.

Assume that following sketches are of shampoo bottle shapes.

Wider Base and Narrower shaped Bottle C provide a better experience. Bottom half consumption was slower compared to the top half. As consumers have experienced the rapidly falling levels of the top half, they feel that the shampoo’s use stretched over a longer period. (mmm…..”Contrast Principle” of psychology- Making people unconsciously compare the top half and bottom half). Bottle B has flat experience curve. Bottle C has negative experience effect at the end.

Your lunch meal may not be wonderful, but if you end the meal with a nice dessert, you will come out happier. Make sure that your product or service ends in a happy mode, as movies end in Marriages or the Happy Family Union.