Only people who believe exertion zaps willpower get a boost from glucose
People who need sugary snacks to stay sharp throughout the day could be prisoners of their own beliefs. The brain works just fine without regular shots of sugar in people who believe their willpower is unlimited, a new study shows.
“There's a dominant theory in psychology that willpower is limited, and whenever you exert yourself to do a hard task or to resist a temptation, you deplete this limited resource,” says psychologist Carol Dweck from Stanford University.
Previous studies have shown that mental exertion diminishes blood glucose levels and that a person’s willpower can be rejuvenated by ingesting a sugary drink. But Dweck’s earlier work led her to suspect that people’s attitudes about willpower may be responsible for that effect.