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Once upon a time, I decided to treat myself to a nice dinner at a popular restaurant in town. I was looking forward to enjoying a delicious meal. The menu offered a variety of options, and I couldn’t wait to taste the flavours.

I placed the order with excitement. However, as the dishes arrived, I was very disappointed. The taste and flavours were not up to my expectations.

After that dish, the server brought a dessert platter. I started tasting the dessert without any hope after that dish but guess what? The dessert was absolutely full of flavours surpassing all my expectations and making up for the earlier disappointment.

I was really very happy and wish to have the same dining experience here again.

But why is it so? Where does all that disappointment go?

The peak-end rule is not only applicable in UX but also in other industries such as food, healthcare even in real life etc.

Have you ever listened to the phrase “ All is well that ends well”? Whenever you go through a very tough phase but if at last everything gets well and sorted. What is your reaction at the end? Weren’t you feel happy? How do you rate that whole experience?

People mostly rate their overall experience based on peaks and end moments rather than the total sum or average of every moment of the experience.

Additionally, When experiencing an uncomfortable or painful experience, it has been proven that gradual relief from that discomfort or pain, rather than immediate comfort, provides individuals with more positive memories from an experience. It is, therefore, all my disappointment disappears after that dessert platter and a tough experience with a happy ending tend to make the overall experience positive.

According to the article by Nir and Far, Our brains don’t have the capacity to remember everything. Evolutionarily, it makes sense for us to only keep the memories that most aided our survival.

Remembering the most painful and pleasurable moments helped us avoid them or seek them out in the future

Positive events aren’t the only things that have an impact on how people feel about a product or service. Negative events also provide emotional peaks and can contribute to a user’s lasting impression of an experience. i.e. Peak end rule applies to both material goods and pain.

The peak–end rule, also a cognitive bias, is known as a memory bias because it impairs the recall of a memory. We remember intensely emotional events more than less emotional events, and this has an effect on how we perceive an experience:

we recall not the sum of how we felt throughout the experience but the average of how we felt during the peak emotional moments and at its end.

In other words, we remember our life experiences as a series of representative snapshots rather than a comprehensive timeline of events.

Our feelings during the most emotionally intense moments and at the end are averaged in our minds and heavily influence how we assess the overall experience to determine if we’d be willing to do it again or recommend it to others. Individuals demonstrate better memory for events that are more emotionally intense. It also concludes that the length of the whole experience is less important than the peak–end moments.

The peak–end rule is thereby a specific form of the more general extension neglect and duration neglect.

Let’s take an example from Daniel Kahneman (2012), author of the international bestseller Thinking, Fast and Slow,” psychologist, and recipient of the Nobel prize for his longtime research into judgment and decision-making.

Two patients underwent the same procedure. It lasted eight minutes for patient A and 24 minutes for patient B. While both reported a similar pain level overall, the duration for patient B was three times as long (Kahneman, 2012).

Who had the worst recollection, patient A or patient B?

Surprisingly, it was patient A. Although their procedure was much shorter, they reported a higher degree of pain in the final minutes than patient B. Duration was not as important as the unpleasant memory of what happened at the end.

Kahneman’s example supports the peak–end rule. For patient B, “the longer experience is perceived as less painful even though it includes more pain in total, but ends with a period of less intense pain”.

At one point the peak-end rule states that our memories are shaped by the strongest and end parts of an experience. However, when it comes to virtual reality, where the experiences are not as true to our real life or aren’t happening to us in reality, this rule may not have as much of an impact. VR experiences may not create the same level of emotional intensity or lasting impressions as real-life experiences do.

So now let’s conclude the above discussion

According to NN Group: The peak–end rule is a cognitive bias that impacts how people remember past events. Intense positive or negative moments (the “peaks”) and the final moments of an experience (the “end”) are heavily weighted in our mental calculus.

According to Kahneman (2012) — and based on his research and theoretical assumptions — the peak–end rule may result from evolutionary bias. He distinguishes between two aspects of the self.

The “experiencing self” goes through discomfort or pain at the time of the event. In contrast, the “remembering self” is “dominated by the most extreme moment of an experience,” influencing behaviour and choices. Its function, Kahneman says, is to help us avoid future moments that could result in post-traumatic stress.

Source: Positive Psychology

The impact of the negative peak

As we all know that people recall negative moments more vividly than positive ones.

For example, Uber Wait Times — As we know that after we confirm the booking on Uber, we have to wait for a particular amount of time to let the driver reach our location. sometimes there might be a delay from the driver's side to find our location or there may be some other reason, the driver may cancel the booking. What will be your impression if you have for a long period of time alone on a winter night at a location you have first time visited? There will be an emotional negative peak and that can lead to a decrease in traffic on the app.

Uber knows that there is not any alternative to waiting time but what if that waiting time can be replaced with some fun activity or animation or with some information? So Uber used the concept of idleness aversion in which they are using the free time of users into telling them what’s happening behind the scene where users are presented with the animation along with driver location, details, estimated time of arrival etc. In this way, customers feel that they are making some progress and Uber ends that negative experience on a positive note and reduces their post-request cancellation rate.

Source: Laws of UX

Uber Identifies the moments when their product is most helpful, valuable, or entertaining and designed it to delight the end user.

The peak-end rule is basically influenced to a cognitive bias known as the recency effect, which states that items near the end of a sequence are the easiest to recall or we tend to have better memory for the end of the experience than the beginning (recency > primacy). That’s why when I have been served the tasty dessert platter, my perception of that restaurant begins to change.

The impact of the positive peak

Let’s take another example of Duolingo

To make learning a language enjoyable & fun, Duolingo keeps its users engaged by celebrating their successes and giving them a feeling of accomplishment at the end of completing an exercise with the help of gamification/animation since the peak-end rule focuses around the most intense moments here which include being successfully able to complete a particular exercise thus generates a positive emotional peak at the end, therefore, turning out whole experience to be amazing.

Source: NN Group

But how did Uber or Duolingo know the critical moments in an app/website?

Designers at Uber/Duolingo pay close attention to the most intense points and the final moments (the “end”) of the user journey. i.e. we can know about these critical moments through “Journey Mapping”.

If we look at the whole situation or use the app once from the user’s perspective, try to keep ourselves in the users’ shoes (their emotions, mindsets and actions), then we will easily be able to understand users' pain points, emotional peaks (both negative & positive) and then we can iterate it and design it so that all the pain points or negative emotional peaks end on a positive note.

Recognizing that it is less about the entire experience and more about particular aspects, we can reframe or refocus our attention and thinking such as various apps do in order to convert the most intense peak & end moments into a positive one.

The peak-end rule is influenced by the representativeness heuristic, which is a mental shortcut used to help individuals make quick decisions by prototyping people or moments. That’s why this observation, known as the peak–end rule, strongly suggests we should pay close attention to these critical moments to ensure users evaluate an overall experience positively.

Source: Laws of UX

The impact of Last impressions

As much as the peak negative & positive moments generates an emotional response so do the end moments.

Submitting a job application on an online portal, a college admission form on a website, sending important mail, various checkout and payment processes, edge cases which include any particular service not available in an app/website due to backend, page not found, error 404, getting no search results on a search engine for a particular product, topic etc there can be numerous examples which explain the critical moments in a particular user end journey. You can read more about examples of last impressions here: Guidelines for Search Engine “No Results” Pages & The Peak–End Rule: How Impressions Become Memories

And… That’s a wrap!

Thanks for reading! I hope you have found this reading interesting.

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