Discussion by: Zeuglodon
If you haven't read Daniel Kahneman's Thinking, Fast and Slow, then I strongly recommend you find a copy, because it contains chapters on the oddities of human choices, an explanation of how those arise from at least two different thought modes (called System One and System Two in the book), and a mixture of detailed studies and professional experience in the field. It's worth the price of admission.
However, the section I found most interesting was the one that detailed the predictions and uses of two modes of thinking: an "experiencing self", which feels and senses events in real time, and a "remembering self", which offers an after-the-fact interpretation of such events based on memory. This section intrigued me because it pointed out that a mismatch between the interpretations offered by both "selves" could lead to people making objectively self-defeating choices.
For instance, when faced with two painful medical procedures (I think it was a colonoscopy, but my memory might be at fault) in one study, one group were given a 60 second procedure, whereas a second group were given a 90 second procedure, with the first 60 seconds being as painful as that of the other group's, but the next 30 seconds containing a decrease in pain until it became tolerable. By most objective predictions, the first procedure was less painful than the second, since the second contained the pain of the first and then some. The surprise, though, was that patients remembered the second procedure as the less painful simply because it ended on a relatively bearable note, which led to them suggesting that they would choose the longer procedure over the shorter one next time.
Kahneman explains this by suggesting that the remembering self is insensitive to duration, and focuses instead on the peak of the experience compared with the end. By this measure, the first group on average had it worse, because the end and the peak were roughly the same and yield an equally high average level of pain. By contrast, the average for the second group would be lowered by the fact that the last experience of pain was relatively low, giving the impression that overall, this was not that bad an experience. He goes into far more detail than I do here, and I strongly recommend reading the relevant chapters if you can hunt down the book, but this is the essence of it for the purposes of my discussion.
Now, my question is: in the context of evolutionary biology, why would an organism arise that could choose a worse experience over a less painful one? If the remembering self has such a skewed memory of what the experiencing self went through, then that would suggest an organism might endanger its survival or reproductive prospects by misjudging the risks it was putting itself through. Would there be a reason for an organism to ignore the duration of pain and focus only on how it ended and what its worst moment was?