More Is Meaningful: The Magnitude Effect in Intertemporal Choice Depends on Self-Control

Impulsivity is a variable behavioral trait that depends on numerous factors. For example, increasing the absolute magnitude of available choice options promotes farsighted decisions. We argue that this magnitude effect arises in part from differential exertion of self-control as the perceived importance of the choice increases. First, we demonstrated that frontal executive-control areas were more engaged for more difficult decisions and that this effect was enhanced for high-magnitude rewards. Second, we showed that increased hunger, which is associated with lower self-control, reduced the magnitude effect. Third, we tested an intervention designed to increase self-control and showed that it reduced the magnitude effect. Taken together, our findings challenge existing theories about the magnitude effect and suggest that visceral and cognitive factors affecting choice may do so by influencing self-control.