Have you ever come out of a stressful exam or interview and thought that you could devour a whole tub of ice-cream? Or maybe it was an emotional movie that left you feeling tired. Why do many people who endure a stressful experience want to have a drink or eat comfort foods that are high in fat and sugar? One interesting idea is that when we give in to these temptations, we are experiencing ego depletion.
Ego depletion comes from American psychologist Roy Baumeister, who believes that enduring something stressful exhausts our capacity for willpower to the extent that we give in to temptations that we would rather avoid. In one of his studies, he made hungry students eat bitter radishes （注1) rather than delicious chocolate cookies. Even people who like a bit of radish in their salad would find that task difficult. However, Baumeister was not interested in eating habits. He was really interested in how long the students would persevere on an insoluble geometry task. The students who had been allowed to eat the cookies stuck at the geometry task on average for about twenty minutes, whereas those who were forced to eat the radishes gave up after only eight minutes. They had used up all their willpower to eat the radishes so they were left with less reserve to cope with another situation of completing a difficult problem.
Performance on one task that requires effort can therefore have unforeseen consequences for a subsequent situation that is completely unrelated except that it requires effort. This is why Baumeister regards willpower as a mental muscle that can become exhausted.
Just maintaining one's composure（注2) can be ego depleting. Not being allowed to laugh at hilarious comedy sketches, firing employees, enduring others in crowds are all situations where we have to exert self-control that leads to ego depletion. We exhibit more ego depletion at the end of the day, which is when couples are more likely to fight, after a hard day at the office. We become less tolerant of others and blame our spouses for the problems that are really generated by work.
When we are ego depleted, we eat more junk food, drink more alcohol and generally have less control over our behaviour. Not only do we give in to temptation, but we have an increased desire for forbidden fruit.
(Adapted from The Domesticated Brain)
（注1) radish : ハツカダイコン
（注2) composure : 心の落ち着き