The Peak-End Rule: How Your Memory Shapes Experiences

1. PEAK END RULEHow our memory makes short-cuts to remember experiences Warning: Images in this file are compressed. Please refer to the google drive for a non-compressed version

2. ? What do you remember best about your last holiday? To use to test audience at the start of the section

3. DEFINITION 2

4. The Peak End Rule We judge our past experiences almost entirely on how they were at their peak and how they ended Net pleasantness or unpleasantness, or the length of the experience is almost entirely disregarded 3 A memory heuristic which takes the peak (the best or worst bit) and the end bit or how it concluded to judge our overall experience. It can apply to both positive and negative experiences.

5. Peak End Rule 4 We judge our past experiences mostly by how they peaked and how they ended. The peak and end can be both positive or negative, pleasant or unpleasant.

6. Kahnemantalks about the ‘Experiencing self’ and the ‘Remembering self’: “We actually don't choose between experiences, we choose between memories of experiences.” 5

7. SCIENTIFIC EVIDENCEEvidence that supports the existence of peak end rule 6

8. Peak End Rule during physical exercise Sports psychologists were interested whether the peak end rule also applies to people’s overall memory of a workout session. Study task: 41 women who don’t exercise regularly completed a 20 minute treadmill workout. Participants reported their feelings every 2 minutes during the workout on a scale from -5 (very bad) to +5 (very good). Shortly afterwards as well as 2 and 7 days later, they were asked how they felt about the exercise overall. Results: Participants’ memory of the workout was strongly influenced by their feelings at the peak (i.e. the most intense moment) and the end. The researchers calculated the peak-end rule predicted 50% of the overall experience. Moreover, the peak end rule was strongest directly after the session and declined during the following days. Source: Hargreaves, E. A., & Stych, K. (2013). Exploring the peak and end rule of past affective episodes within the exercise context. Psychology of Sport and Exercise, 14(2), 169–178.

9. The Peak-End Rule while studying for an exam (i) Researchers investigated the peak end rule in the context of studying a foreign language. Study task: Participants studied two lists of Spanish vocabulary. Long list Short list 30 extremely difficult words + 15 moderately difficult words afterwards 30 extremely difficult words Afterwards participants were asked which list they would prefer to study the next day and which list they found easier to study. Source: Bridgid, F. (2010) Ending on a high note: Adding a better end to effortful study. Journal of Experimental Psychology: Learning, Memory, and Cognition, 36(6), 1548-1553

10. The Peak-End Rule while studying for an exam (ii) Researchers investigated the peak end rule in the context of studying a foreign language. Results: Despite the fact that the long list contained just as many difficult words plus an extra 15 words, participants preferred the long list. • 73% choose to study the long list the following day • 70% found the long list less difficult • 71% found the long list less stressful • 70% actually thought the shorter list took longer to learn Long list 30 extremely difficult words + 15 moderately difficult words afterwards Explanation: The long list ended with 15 moderately difficult words and thereby created a more positive end. This positive ending influenced participants’ overall feelings and is evidence for the peak-end rule. Source: Bridgid, F. (2010) Ending on a high note: Adding a better end to effortful study. Journal of Experimental Psychology: Learning, Memory, and Cognition, 36(6), 1548-1553

11. Peak end rule in medical procedures - Scientific Background (i) A classic experiment by Donald Redelmeierand Daniel Kahneman in 1996 asked patients to rate a negative experience – a colonoscopy which varied in degree of pain and length. They found that memories were correlated with how bad the pain was at its peak and how painfully it ended. Source: Redelmeier, D. A, Kahneman, D., “Patients memories of painful medical treatments: real time and retrospective evaluations of two minimally invasive procedures”, 1996, Pain, 66, 3-8 7

12. Peak end rule in medical procedures - Scientific Background (ii) A classic experiment by Donald Redelmeierand Daniel Kahneman in 1996 asked patients to rate a negative experience – a colonoscopy which varied in degree of pain and length. STUDY TASKS: 154 patients due to undergo a colonoscopy were recruited. During and after the operation, patients’ real time ratings of the level of pain and retrospective evaluations were tracked using a device that asked them to rate the pain experienced from 0 ‘no pain’ to 10 ‘intolerable pain’. The procedure lasted from just 4 minutes up to 69 minutes with varying amounts of pain. RESULTS: They found patients’ memories were correlated with how bad the pain was at its peak and how painfully it ended. Patients rated colonoscopies as less unpleasant if an interval of mild pain was experienced at the end of the procedure even though it was longer. Source: Redelmeier, D. A, Kahneman, D., “Patients memories of painful medical treatments: real time and retrospective evaluations of two minimally invasive procedures”, 1996, Pain, 66, 3-8 8

13. Cold hand test - Scientific Background (ii) Kahneman and his colleagues tested peak end rule in another situation, which they termed the ‘cold hand situation’. Again they found that people’s memory of the pain was affected by how the experience ended, not by how long it lasted. Source: Kahneman, D., Fredrickson, B. L., Schreiber, C. A., & Redelmeier, D. A. (1993). When more pain is preferred to less: Adding a better end. Psychological Science, 4, 401-405. 9

14. Cold hand test - Scientific Background (ii) Kahneman and his colleagues asked participants to immerseone hand into a bucket of ice water. …Followed by a 7 minute break… TASK 1 14 degrees C for 60 seconds… TASK 2 14 degrees C for 60 seconds; then 15 degrees C for another 30 seconds RESULTS: Participants preferred the longer immersion experience. People noticed their pain decreasing in the final 30 seconds of Task 2. Source: Kahneman, D., Fredrickson, B. L., Schreiber, C. A., & Redelmeier, D. A. (1993). When more pain is preferred to less: Adding a better end. Psychological Science, 4, 401-405. 10

15. Films and Peak End Rule – Scientific Background (i) Researchers Barbara Frederickson and Daniel Kahneman found the length of film clips had no effect on ratings. What mattered was the peak and the end. Source: Frederickson, B. and Kahneman, D. “Duration neglect in Retrospective Evaluations of Affective Episodes” Journal of Personality and Social Psychology, 1993, Vol 65, no 1, 45-55 11

16. Peak End Rule – Scientific Background (ii) Researchers Barbara Frederickson and Daniel Kahneman studied how we rate films. STUDY TASKS: Participants were shown different length film clips of positive and negative topics, such as penguins diving off a glacier, Gregory Hines tap dancing, Hiroshimaor a man being forcibly drowned. Film length varied between 30 seconds and nearly 2 minutes. Participants rated and ranked each clip. RESULTS: Participants’ ratings were not correlated with the length of the clips ie whether they were short or long clips. Ratings were explained much better by the presence of clear emotional peaks, endings and level of emotional intensity. Source: Frederickson, B. and Kahneman, D. “Duration neglect in Retrospective Evaluations of Affective Episodes” Journal of Personality and Social Psychology, 1993, Vol 65, no 1, 45-55 12

17. Watching DVDs - Peak End RuleScientific Background (i) A group of researchers at Dartmouth College tested for the presence of peak end rule on gifts and experiences watching different quality DVD films. Source: Do, A., Rupert, A., Wolford, G. (2008). Evaluations of pleasurable experiences: The peak–end rule. Psychonomic Bulletin & Review. 15 (1), 96-98) 13

18. Watching DVDs - Peak End Rule – Scientific Background (ii) A group of researchers at Dartmouth College tested for the presence of peak end rule on gifts and experiences watching different quality DVD films. STUDY TASKS: Participants selected 1 or 2 free DVDs sequentially. DVDs varied in quality. List A were classic blockbusters and highly rated. List B were medium-rated films. • Group 3 chose first an A-rated DVD, then a B-rated DVD; and • Group 4 chose first a B-rated DVD, then an A-rated DVD • Group 1 selected only a DVD from list A; • Group 2 selected a DVD from the B-rated DVD list; Participants then rated their overall experience. RESULTS: Those who received only an A-rated DVD or B then A rated their overall experience higher than those who received B only, or A then B. Source: Do, A., Rupert, A., Wolford, G. (2008). Evaluations of pleasurable experiences: The peak–end rule. Psychonomic Bulletin & Review. 15 (1), 96-98) 14

19. Peak End Rule in the recall of labour pain (i) EranChajut, Dan Arielyand their colleagues explored if mothers' memories of childbirth showed evidence of peak end effect. Source: Chajut, E. et Al. (2014). In Pain Thou Shalt Bring Forth Children: The Peak-and-End Rule in Recall of Labor Pain. Psychological Science, 25(12), 2266–2271 15

20. Peak End Rulein the recall of labour pain – Scientific Background (ii) STUDY SET-UP: 320 women indicated the degree of pain they were experiencing while giving birth in the delivery department of the Rabin Medical Center in Israel. Pain was indicated on a scale of 0 to 100 every 20 minutes. • The researchers followed up 2 days and 2 months after delivery, asking the mothers to rate their overall evaluation of the pain they remembered during childbirth. RESULTS:Mothers' recollections of labour did indeed follow the peak end rule. Taking the average of the most painful moment of labour (the peak) and the end of labour (the end) was thebest predictorof recollected labour pain. The duration of the experience did not impact the recollection of pain. Source: Chajut, E. et Al. (2014). In Pain Thou Shalt Bring Forth Children: The Peak-and-End Rule in Recall of Labor Pain. Psychological Science, 25(12), 2266–2271 16

21. EXAMPLES 17

22. The Peak End Rule “Welcome! You have arrived on yet another on time flight. Last year over 90% of Ryanair flights landed on time, beating every other European airline.”

23. BEing TBA: Building a peak-end experience • Ideas to create a memorable peak-end experience in a creds meeting or BE workshop • A fun eating experiment to show diversification bias: If we can choose from a large number of snacks, we generally consume more as we have a tendency to prefer variety and try different snacks. For example, people will eat more M&Ms from a bowl containing many colours than from a bowl containing only one colour — even though all M&Ms have the same flavour. • Being BE detectives - there are several videos on change blindness and inattentional blindness that highlight the strong influence of BE on our attention and thinking. The first two are particularly good because they are interactive and ask the audience to work out the answer. • Inattentional blindness - Invisible Gorilla: https://www.youtube.com/watch?v=vJG698U2Mvo • Inattentional blindness - murder investigation: https://www.youtube.com/watch?v=ubNF9QNEQLA • Change blindness - door study: https://www.youtube.com/watch?v=uO8wpm9HSB0 • Change blindness - Harvard conference: https://www.youtube.com/watch?v=lKP5hI2MhBI#t=4m26s • Being BE analysts- getting people to be BE detectives for an element of mapping the context whilst watching a research video e.g. one person does social/cultural, another looks at branding, another physical surroundings • BE spotting: ask them to detect BE in their own or their consumers’ everyday-life and then think about how it may inform the research methodology • Fun and engaging BE videos • Simpson and the endowment effect: https://vid.me/fX7l or Youku • Social norms in the elevator: https://www.youtube.com/watch?v=BgRoiTWkBHU • Priming in the movie Focus: https://www.youtube.com/watch?v=X7O_i05YBlg • Have a small gift for them e.g. TBA books

24. Positive expressions of the peak-end rule: ending on a high note or creating suspense… Party bags! 18

25. Qantas leveraging peak end rule and reciprocity with Lindor chocolates Qantasrecently stopped serving full in-flight meals and instead served passengers a light snack. But they finish their service by handing around Lindor chocolates at the end of a meal – a peak end! Giving something pleasurable for free also helps to create loyalty and reciprocityeffects. 19

26. Ideas for peaks in presentations, pitches and talks • Use this checklistto ensure a peak/end and make yourself memorable. • If you tick none, you’re sunk. • acompelling story; • a repeatable phrase; • a piece of pure theatre; • an unlikely setting; • an astounding visual; • audience participation; • best of all, an idea!” 20

27. The ‘Kahneman Way’ of eating a sandwich When eating a sandwich a consumer will have a more positive experience if the last bite is taken from the middle of the baguette (the part with filling) compared to the end of the baguette (just bread). 21

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32. Do, A., Rupert, A., Wolford, G. (2008). Evaluations of pleasurable experiences: The peak–end rule. Psychonomic Bulletin & Review. 15 (1), 96-98) Chajut, E. et Al. (2014). In Pain Thou Shalt Bring Forth Children: The Peak-and-End Rule in Recall of Labor Pain. Psychological Science, 25(12), 2266–2271 Frederickson, B. and Kahneman, D. “Duration neglect in Retrospective Evaluations of Affective Episodes” Journal of Personality and Social Psychology, 1993, Vol 65, no 1, 45-55 Kahneman, D., Fredrickson, B. L., Schreiber, C. A., & Redelmeier, D. A. (1993). When more pain is preferred to less: Adding a better end. Psychological Science, 4, 401-405. Kahneman, D., “Thinking Fast and Slow”, 2011, Allen Lane, p378-385 Redelmeier, D. A, Kahneman, D., “Patients memories of painful medical treatments: real time and retrospective evaluations of two minimally invasive procedures”, 1996, Pain, 66, 3-8 27