When we speak of willpower, we frequently use language that conjures images of physical exertion, said Steven Pinker in The New York Times. We “force” ourselves to go to work. We “restrain” ourselves from eating too many sweets. We “control” our temper, “as if it were an unruly dog.” But it was still surprising when psychologist Roy Baumeister in recent years began sharing the results of a series of experiments that seemed to prove that the will is in many ways like a muscle—use it to resist starting a fight, for instance, and it may be too fatigued to resist a pint of ice cream. In this “immensely rewarding” new book, Baumeister has teamed with New York Times science columnist John Tierney to explore the practical import of his findings. The result is a work filled with “insightful reflections on the human condition.”
Consider it an “instant classic” of behavioral science, said Jamie Holmes in TheDailyBeast.com. One of Baumeister’s most surprising discoveries is that willpower is deeply affected by a person’s blood-sugar level. Indulging in a tasty milk shake, he found, seems to strengthen a test subject’s ability to exert self-control. But so can drinking an unpleasant concoction—provided that the beverage delivers glucose to the brain. That finding “has impressive explanatory power.” For one thing, it reveals why dieting can be so hard: People need the fuel from food to resist food. It even explains why parole boards are much more likely to risk granting a prisoner freedom after lunch than just before it. A drained brain resists tough choices.
Baumeister and Tierney might actually be exacerbating the problem they’re trying to solve, said Cordelia Fine in The Wall Street Journal. “Willpower offers no shortage of helpful strategies to compensate for weakness of will,” arguing that the will muscle can be strengthened by regular exercise. “Even trivial acts of self-control—like avoiding slouching—can strengthen the capacity for self-discipline in the long term.” But the authors never mention competing research, notably from Stanford’s Carol Dweck, which suggests that willpower is a depletable resource only for those who’ve come to think of it as depletable. Smart as this book is, it’s “unlikely to provide the final word” on the subject.