The peak-end rule

The peak-end rule affects how an individual remembers an event by simplifying the memory and emphasizing its peak and endings.³ The peak-end rule can be problematic, as human events and memories are complex in nature. By simplifying a memory, individuals misinterpret past events and risk making wrong assumptions and poor decisions.

An example of how the peak-end rule can alter our memories and thus our decision-making is our negative experiences at the dentist. The dentist can be an unpleasant experience for many, but is required so that we regularly maintain and check-up on our dental health. If we experience an adverse event at the dentist and remember our dentist trip as primarily negative, this could deter us from checking-up on our dental health later on. Therefore, our warped interpretation of our experience at the dentist can significantly impact our choices, bearing consequence to our health.

The peak-end rule is also commonly used by companies to design better experiences for their customers, and create sales. By manipulating customer experiences and focusing on developing product experience peaks and positively ending experiences, customers will tend to remember the product more fondly.

Examples of peak-demand and marketing techniques include surprise discounts at checkout, or providing small departure gifts as customers’ exit an establishment. By making the last impression a good one, customers are more likely to return and think highly of a product.⁴

The peak-end rule is a cognitive bias that develops in individuals for a multitude of reasons.

Representativeness heuristic

Based on work by Dr. Daniel Kahneman and Dr. Barbara Fredrickson, the peak-end rule happens as a result of the representativeness heuristic, which is a mental short-cut used to help individuals make quick decisions by prototyping people or moments.⁵ The representativeness heuristic explains why an event is not judged or remembered by the entirety of its experience, but rather by snapshots of the memory, which trigger an emotional response in individuals.⁶ The retained value of those snapshots then dominates the value of an individual’s experience. Additionally, the peak-end rule is only applicable if a moment or experience has definite beginning and end periods.

Memory bias – Why the peak is memorable

Individuals demonstrate better memory for events that are more emotionally intense. Though the cause for this is unclear, it has been widely proven in various studies, experiments, and surveys.^7,8,9 Additionally, individuals do not always recognize that the events they remember are more emotionally intense.

Recency bias – Why the end is memorable

Individuals typically remember both the beginning and end of a memory better due to serial position effects, such as primacy bias and recency bias. Recency bias is a cognitive bias that causes individuals to more easily remember something that has happened recently. The peak-end rule is influenced by this bias, which is why we remember both the peak emotional moments and the end.¹⁰

An individual’s representativeness heuristic bias and their tendency to remember emotionally intense moments leads to what is known as the peak-end rule.

The peak-end rule can warp an individual’s perception of past events and memories. By being aware of the cognitive bias, individuals can avoid it or use the peak-end rule to their benefit.

The cognitive bias can be used to our advantage when an individual is aware of it.² By leveraging the bias, individuals can craft how their memories are formed, creating more positive memories.

Ending on a High Note

By ending experiences on a high note, it is typical that they will be remembered in a more positive light. Actively focusing on positively ending experiences can be done in several ways. For example, if an individual has a lousy dinner, they can finish their night by getting ice cream from their favorite restaurant. Finding something positive to focus on can help create positive memories from unpleasant experiences.¹¹

Gradual Relief

Additionally, when experiencing an uncomfortable or painful experience, it has been proven that gradual relief from discomfort or pain, rather than immediate comfort, provides individuals with more positive memories from an experience. Researchers have found that this technique can be used in an array of real-life cases, specifically with an individual’s health. For example, when exercising, if individuals end their exercise at a lower intensity, they are more likely to feel positive about the experience and look forward to future sessions.¹² By making sometimes uncomfortable and challenging exercises end on a gradual positive note, individuals are more likely to exercise, thus ensuring they are working towards their health.

By being aware of the peak-end rule and using it to our advantage, individuals can significantly improve their well-being and happiness by viewing more and more of their memories as positive experiences.²

Avoiding the peak-end rule can help individuals more accurately recall their past experiences, or experience them in a more positive light.

Avoiding Focusing on Negative Elements

Dwelling and remembering negative peaks of a situation or memory enable the peak-end rule to shape our perception of a past event. Consider an individual’s experience of eating at a restaurant. The food was excellent, but the service was poor. By making a conscious effort to focus on the right parts of the meal, such as the quality of the food, an individual can avoid being consumed by an event’s negative elements.

Reframe the Moment

Memories and past events can easily be reframed to create more positive and intense emotions in our recollection of them. By focusing on positive elements of memory or reframing the timeline of a moment, we can change our perception of the memory, and avoid peak-end rule.

The peak-end rule was first brought to light by Israeli psychologist and economist Daniel Kahneman, and researcher Barbara Frederickson. Through their notable study conducted in 1993, titled “When More Pain is Preferred to Less: Adding a Better End,” the researchers found that the human memory seldom records series of events with accuracy, thus giving evidence to the influence of the peak-end rule in our memory processes.¹³

The research study asked participants to endure an uncomfortable (but not dangerous) experimental condition, where individuals were subjected to two versions of the same unpleasant experience. The experiment’s first trial asked study participants to submerge their hand in 14°C water for 60 seconds. The second version of the trial asked study participants to submerge their other hand in 14°C water for 60 seconds. Additionally, participants were asked to keep their hand submerged for 30 seconds while the temperature of the water was raised 15°C. After these two trials, participants were asked which option of the trial they would choose to repeat. Study subjects were found more willing to repeat the second trial, despite the prolonged exposure to uncomfortable temperatures. The study concluded that this happened because “subjects chose the long trial simply because they liked the memory of it better than the alternative, or disliked it less.”¹³

An example of the peak-end rule applies to students and their educational experiences, particularly regarding student-teacher peer assessment. A study conducted by Vincent Hoogerheide, a psychology professor, focused on education and child studies. He analyzed the effects of the peak-end rule in a children’s experiment of giving and receiving peer assessments.¹⁴

The study contained two different experiments, one giving a positive assessment and the other offering a negative evaluation to students. In each experiment, the students received two versions of the assessments with two different lengths. In the overall negative assessment, the more extended version had a moderately negative rating at the end. In parallel, the positive rating also in similar fashion ended with a moderate positive rating. Students remembered the extended assessment as more pleasant and less difficult to process and deal with in both experiments.

Based on these results, Hoogerheide and his research team advised that teachers structure their feedback by ending with the best, or more positive part of the assessment. Even when the evaluation is overall negative, his team notes that it is better to end with the most pleasant or acceptable section of the feedback. Similarly, the positive assessment should also end with the most positive feedback. The study demonstrated that the peak-end rule likely influences children’s memory of the evaluation, and impacts their motivation and learning outcomes if appropriately received.

The peak-end rule has been prevalently studied in medical procedures and has suggested that patients prefer to have more lengthy medical procedures that include a period of decreased discomfort rather than uncomfortable shorter procedures.¹⁶ To summarize, the peak-end rule states that a painful medical treatment is likely to be less aversive if relief from the pain is gradual than if relief is abrupt.¹³

A typical example of the peak-end rule and its effects on medical procedures is the famous patient assessments of uncomfortable colonoscopy procedures. Kahneman and Redelmeier conducted a study in 1996 to assess patients’ appraisals of these uncomfortable procedures to test responses based on their use of the peak-end rule. The study found that study patients consistently evaluated the discomfort of the procedures based on the intensity of the pain at the peak or worst moment and at the final moments of the procedure. Regardless of the length of the procedures or the pain intensity experienced, all colonoscopy patients evaluated their procedures through peak events and ending sentiments¹⁶

Another study conducted by Kahneman and Redelmeier further expanded on the discoveries made in their initial 1996 study. The study took colonoscopy patients and randomly divided the patients into two groups. One group of the patients underwent a colonoscopy procedure where the scope was left in for an additional 3 minutes but not moved, causing discomfort, but not causing pain for the patients. The other group of study participants underwent typical colonoscopy procedures. When participants were asked to recall and evaluate their experiences from the experiment, the experiment found that patients who had more prolonged colonoscopy procedures rated their experience as less painful than those who underwent the typical colonoscopy procedure. Additionally, patients who felt prolonged discomfort were far more likely to return for subsequent procedures. The gradual release in discomfort from these more prolonged procedures led to patients evaluating the experience as a more positive experience than the other set of patients.¹⁷

What it is

The peak-end rule is a cognitive bias that changes the way individuals recall past events and memories. Based on the peak-end rule, individuals judge a past experience based on the emotional peaks felt throughout the experience and the end of the experience.

Why it happens

The peak-end rule occurs due to representativeness heuristic bias, memory bias, and recency bias. The representativeness heuristic bias is a bias that causes an individual to remember an experience in snapshots of a memory, rather than its entirety. Memory bias refers to an individual’s ability to better remember a memory due to the emotional intensity experienced during the event. Recency bias refers to an individual’s ability to remember the end of an event better, as it is the most recent thing that happens, thus they can better remember it. An individual’s tendency to remember emotionally intense moments, and the end of events, leads to what is known as the peak-end Rule.

Example 1 – Ending with positive statements creates better learning assessments

The peak-end rule is common in education settings and student feedback assessments. Students remember and react better to feedback if student assessment end with a positive statement. Students can then receive the assessment better and motivate themselves to achieve better learning outcomes from the evaluation.

Example 2 – Medical patients would rather endure longer uncomfortable procedures than shorter painful procedures

The peak-end rule is also ubiquitous in medical procedures and has been studied extensively in the medical context. Studies assessing patients and uncomfortable procedures, such as colonoscopy procedures, noted that participants preferred having longer procedures that include a period of decreased discomfort rather than uncomfortable shorter procedures.

How to avoid it

After developing an awareness for the peak-end rule, it can be further avoided by reframing memories and focusing on positive moments instead of negatives one’s from an event.