Willpower

was essentially no evidence for it, and lots of reasons to think the opposite was true. For example, if the theory of sublimation was correct, then artists’ colonies should be full of people sublimating their erotic urges, and therefore there should be relatively little sexual activity. Have you ever heard of an artists’ colony known for its lack of sex?
    Still, Freud was onto something with his energy model of the self. Energy is an essential element in explaining the liaisons at artists’ colonies. Restraining sexual impulses takes energy, and so does creative work. If you pour energy into your art, you have less available to restrain your libido. Freud had been a bit vague about where this energy came from and how it operated, but at least he had assigned it an important place in his theory of self. As a kind of homage to Freud’s insights in this direction, Baumeister elected to use Freud’s term for the self: ego . Thus was born “ego depletion,” Baumeister’s term for describing people’s diminished capacity to regulate their thoughts, feelings, and actions. People can sometimes overcome mental fatigue, but Baumeister found that if they had used up energy by exerting willpower (or by making decisions, another form of ego depletion that we’ll discuss later), they would eventually succumb. This term would later appear in thousands of scientific papers, as psychologists came to understand the usefulness of ego depletion for explaining a wide assortment of behaviors.
    How ego depletion occurs inside the brain, initially a mystery, became clearer when two researchers at the University of Toronto, Michael Inzlicht and Jennifer Gutsell, observed people who were wearing a cap that covered the skull with a dense network of electrodes and wires. This method, called electroencephalographic recording (EEG), enables scientists to detect electrical activity inside the brain. It can’t exactly read someone’s mind, but it can help map out how the brain deals with various problems. The Toronto researchers paid special attention to the brain region known as the anterior cingulate cortex, which watches for mismatches between what you are doing and what you intended to do. It’s commonly known as the conflict-monitoring system or the error-detection system. This is the part of the brain that sounds the alarm if, say, you’re holding a hamburger in one hand and a cell phone in the other, and you start to take a bite out of the cell phone. The alarm inside the brain is a spike in electrical activity (called event-related negativity).
    With their skulls wired, the people in Toronto watched some upsetting clips from documentaries showing animals suffering and dying. Half the people were told to stifle their emotional reactions, thereby putting themselves into a state of ego depletion. The rest simply watched the movies carefully. Then everyone went on to a second, ostensibly unrelated activity: the classic Stroop task (named after psychologist James Stroop), requiring them to say what color some letters are printed in. For example, a row of XXX s might appear in red, and the correct response would be “Red,” which is easy enough. But if the word green is printed in red ink, it takes extra effort. You have to override the first thought occasioned by reading the letters (“Green”) and force yourself to identify the color of the ink, “Red.” Many studies have shown that people are slower to answer under these circumstances. In fact, the Stroop task became a tool for American intelligence officials during the cold war. A covert agent could claim not to speak Russian, but he’d take longer to answer correctly when looking at Russian words for colors.
    Picking the right color proved to be especially difficult for the people in the Toronto experiment who had already depleted their willpower during the sad animal movie. They took longer to respond and made more mistakes. The wires attached to their skulls revealed notably sluggish activity in the conflict-monitoring system of the brain: The alarm signals for mismatches were weaker. The results showed that ego depletion causes a slowdown in the anterior cingulate cortex, the brain area that’s crucial to self-control. As the brain slows down and its error-detection ability deteriorates, people have trouble controlling their reactions. They must struggle to accomplish tasks that would get done much more easily if the ego weren’t depleted.
    That ego depletion