People tend to make decisions based on recent events, which may seem more important than all previous experience, especially if they are positive.
Martin Vestergaard, from the Department of Physiology, Developmental Biology and Neuroscience at the University of Cambridge, and a group of colleagues conducted a series of experiments to find out how negative or positive events affect future decision making. The studies were built on the principle of gambling: the participants were required to make quick decisions and as a result receive several fiat coins. Most of the subjects consistently chose options where the amounts received increased over time, even if the total amount they ended up earning was less.
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The results of the experiment showed that most people tend to overestimate the significance of the “happy ending” – the latest experience that turns out to be better than the previous one. The researchers give the following analogy: imagine two options for a three-course dinner. In one embodiment, the first dish is not very tasty, the second is delicious, and the third is delicious. Most of us will rate this meal much more highly than another one in which the most delicious dish is the first and the least delicious is the third, although they are technically “equal” in quality.
Scientists believe that it would be too difficult for the brain to make decisions by evaluating all previous experience, and in most cases it only compares the last event with several previous ones. At the same time, the most recent events seem to be especially important, which is why a particularly successful recent experience can easily move a person not to rash steps that ignore all previous experience.
However, a little less than a quarter of the study participants were not subject to this effect: they perfectly remembered all their past experiences, and fleeting success did not prevent them from making sound and informed decisions. Interestingly, this feature was in no way connected with the age and type of activity of the participants in the experiment. Westergaard plans to use tomography to find out if there are any peculiarities in the brain function of these people in the future.
For details, see M. Vestergaard, W. Schultz “Choice mechanisms for past, temporally extended outcomes”, Proceedings of the Royal Society B: Biological Sciences, online publication 7 July 2015.