Sugar or spice: Using I³ metatheory to understand how and why glucose reduces rejection-related aggression

Social rejection can increase aggression, especially among people high in rejection sensitivity. Rejection impairs self-control, and deficits in self-control often result in aggression. A dose of glucose can counteract the effect of situational factors that undermine self-control. But no research has integrated these literatures to understand why rejection increases aggression, and how to reduce it. Using the I³ model of aggression, we proposed that aggression would be highest under conditions of high instigation (rejection), high impellance (high rejection sensitivity), and low inhibition (drinking a beverage sweetened with a sugar substitute instead of glucose). As predicted, aggression was highest among participants who experienced social rejection, were high in rejection sensitivity, and drank a placebo beverage. A dose of glucose reduced aggression, especially among rejected people high in rejection sensitivity. These findings point to the importance of self-control in understanding why social rejection increases aggression, and how to prevent it. Aggr. Behav. 41:537-543, 2015.