Much recent research suggests that willpower—the capacity to exert self-control—is a limited resource that is depleted after
exertion. We propose that whether depletion takes place or not depends on a person’s belief about whether willpower is
a limited resource. Study 1 found that individual differences in lay theories about willpower moderate ego-depletion effects:
People who viewed the capacity for self-control as not limited did not show diminished self-control after a depleting experience.
Study 2 replicated the effect, manipulating lay theories about willpower. Study 3 addressed questions about the mechanism
underlying the effect. Study 4, a longitudinal field study, found that theories about willpower predict change in eating behavior,
procrastination, and self-regulated goal striving in depleting circumstances. Taken together, the findings suggest that reduced
self-control after a depleting task or during demanding periods may reflect people’s beliefs about the availability of willpower
rather than true resource depletion.