Research Published July 27 2016
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Resist the temptation of an immediate reward is often essential to achieve our long-term goals.

Mathias Pessiglione’s team at the Institut du Cerveau – ICM, has made the assumption of a limited ” self-control ” daily stock, allowing us to act without impulsivity and to make rational decisions.

To test this idea, researchers asked three groups of volunteers to participate in behavioural studies. The first group had to solve complicated exercises for more than 6 hours. During this time, the second group was confronted with simple exercises, while the third group was enjoying books or video games. At regular intervals, researchers asked participants to choose between an immediate reward, receive a small sum of money straight away, or a reward in the long term, a larger sum of money later on.

People submitted to difficult exercises have chosen the small sum immediately, which means they have favoured an impulsive choice rather than a more profitable one in the long term. Thus, cognitive “fatigue” would inspire us to make more impulsive choices.
Who’s responsible ? A small area of the brain located in the prefrontal cortex, and solicited both when performing complex tasks, and making financial choices. “The activity of this area decreases with fatigue, and the more its activity decreases, the more impulsive choices increase,” explains Mathias Pessiglione.

This work highlights a mechanism explaining why, after a hard day’s work, our impulsivity increases when it comes to making economic decisions. These results have implications in the management field, in fact, the number and duration of breaks during work should be adapted to avoid cognitive fatigue. “Too hard work not only has an impact on our economic decisions but can eventually lead to pathological conditions such as burn-out syndrome “, concludes the researcher.

Reference : Neural mechanisms underlying the impact of daylong cognitive work on economic decisions. Bastien Blaina, Guillaume Hollardc, and Mathias Pessiglione. PNAS, 2016.