Social exclusion impairs self-regulation.

Abstract
Six experiments showed that being excluded or rejected caused decrements in self-regulation. In Experiment 1, participants who were led to anticipate a lonely future life were less able to make themselves consume a healthy but bad-tasting beverage. In Experiment 2, some participants were told that no one else in their group wanted to work with them, and these participants later ate more cookies than other participants. In Experiment 3, excluded participants quit sooner on a frustrating task. In Experiments 4-6, exclusion led to impairment of attention regulation as measured with a dichotic listening task. Experiments 5 and 6 further showed that decrements in self-regulation can be eliminated by offering a cash incentive or increasing self-awareness. Thus, rejected people are capable of self-regulation but are normally disinclined to make the effort.