A human bias towards happy endings can skew our memory of an experience and the likelihood of choosing it again.
Take holidays, for example. We might return to a place where a previous trip ended with a pleasant experience, rather than one where things ended on a sour note, despite the fact that overall we had a wonderful time at both.
This bias can extend to other areas of life, such as who to vote for or what stock to buy.
“One of the numerous foibles that prompt us to make poor decisions is known as the ‘bankers fallacy’, the tendency to focus on short-term growth at the expense of long-term value,” write Martin Vestergaard and Wolfram Schultz from the University of Cambridge, UK, in the Journal of Neuroscience.
Exploring this “happy ending effect”, the researchers showed that making decisions based on past experiences activates two competing areas of the brain.
A primitive brain region called the amygdala evaluates the overall value of the experience while the anterior insula devalues it if it goes downhill. Experiences further back in time, even if relatively recent, hold less sway in decision making.
For their experiment, the pair recruited 27 healthy male volunteers who were asked to choose which of two pots of coins had the greatest value, presented on a screen while their brains were scanned using functional magnetic resonance imaging (fMRI).
The volunteers, who were told it was a gambling experiment, were paid a fixed fee to take part, with prize money that varied according to their performance.
The task involved watching coins of varying sizes – larger coins carrying greater value – falling from the pots in several different sequences. Participants’ subsequent evaluation was tested using a computational model.
They consistently chose the pot with coins that decreased in size towards the end, without factoring in the overall value of each pot.
Volunteers who made the best decisions had the strongest activation in the amygdala, suggesting that helped them ignore the irrational bias to some degree.
Those more prone to messages from the anterior insula, which is packed with the pleasure-seeking dopamine receptors, could be using their “gut feeling” to make intuitive decisions that are leading them astray, the authors suggest.
The findings question assumptions about the role of these brain regions, they write.
“The study… challenges a popular belief that suboptimal decision making is somehow routed in primitive neural structures whereas more astute reasoning is thought to emerge from the more evolved frontal executive system.”
It could lend insights into neural underpinnings of decision making popularised by Daniel Kahneman in the book Thinking fast and slow, they add, and could inform better choices.
“Sometimes it’s worth taking the time to stop and think,” says Vestergaard. “Taking a more analytical approach to complement your intuitive judgement can help ensure you’re making a rational decision.”