"I can't leave until I make a shot." You'll hear this all the time on a basketball court. Growing up I had a friend that was annoyingly loyal to this behavior. Why? Sure, we all want to make another shot, but is there a more profound reason? The research of Daniel Kahneman gives a possible explanation: The Peak-End rule.
Kahneman is a Nobel-prize winning psychologist famous for being one of the founders of behavioral economics, and, in one of my favorite books, Thinking Fast and Slow, espousing a view of human behavior antithetical to many previously held notions.
The Peak-End rule is a rule that describes the how an event is remembered: Given an event, it is best remembered by the end behavior, not the peak behavior. Basically, when an event occurs we may have a much different experience than how we remember it. The end behavior is more determining of our memory than the peak behavior.
Kahneman's example is from the world of cancer screening procedures: The colonoscopy. The picture to the right is lifted from Kahleman & Redelmeier (1996). It shows two patients, each receiving a colonoscopy. Every 60 seconds the patients were asked to report their perceived pain intensity where 0 = no pain and 10 = extreme pain.
Patient A received a colonoscopy that only lasted for 8 minutes while patient B's experience lasted 23 minutes. Each patient had a peak pain rating of 8/10 and it occurred only once for each. If we define suffering as pain felt over time, that is the integral of pain over time
then patient B suffered greatly compared to A. In fact, more than twice as much as patient A. But there is a surprise 🙂 .
When asked later how painful the colonoscopy was patient B recalled it being less painful than patient A! At the end of the procedure patient B was only a bit uncomfortable. This slight pain, felt at the end, carried more weight into memory than the very painful peak felt at the 10 minute mark. In contrast, patient A was in great pain immediately before the procedure was finished. This imprinted on patient A and defined the experience for this patient.
There is a difference between how an event is experienced and how an event is remembered. And it is how it is remembered that determines our future behavior.
In a later paper, Kahleman & Redelmeier (2003), explored the consequences of this. The patients in the study that had a better memory of the event were more likely to get follow-up work and future colonoscopies. Instinct tells us that getting the procedure done swiftly and incurring the least amount of total pain on the patient is the most prudent way to administer of the procedure. It is not. Not if your goal is to get the patients to return and get more procedures. In other words, ripping the band-aid off will just makes you not want to wear more band-aids.
This behavior is seen in other pain related activities such as going to the dentist. There is also a lot of research about having positive memories. What about vacationing? Is the duration more important to your happiness or a more intense and happy experience? It turns out that people have happier memories of more positive end experiences on vacation than less happy vacations with a longer duration.
It would be nice to see if this effect is seen on a more macro (time-scale) event. What about a Calculus course? What if a student left the course dong something other than a brutally long exam? I would think that at this time scale the effect would wash out but who knows, right?