The brain keeps track of the value of an experience as well as how it unfolds over time; overemphasising the ending may trigger poor decision-making, according to new research published in The Journal of Neuroscience.

A bout of bad weather at the end of a holiday can sour the impression of the entire trip. The tendency to focus on the ending may stem from how the brain encodes the value and temporal profile of experience.

Vestergaard and Schultz created a computational model explaining how participants chose between two streams of coins varying in size where larger coins have a higher value. The model revealed a discrepancy between the true value of experience – how much money was in the stream – and the value people placed on how it developed. People disliked when the coins decreased in size, even if the stream was worth more money overall, resulting in their making the wrong decision.

The findings from the model tracked with brain activity data from fMRI. During the task, the amygdala encoded the actual value of a choice, while the anterior insula encoded dislike towards a negative ending – in this case, if the coin stream decreased in size. This representation can overpower information from the amygdala, leading people to undervalue experiences that end poorly despite starting well. The best decision-makers had the strongest representation in the amygdala, indicating an ability to disregard a lesser ending and choose the better option.