A programmatic series of 12 studies (including 8 experiments, 3 correlational studies, and one archival study) tests the hypothesis that feeling excluded and/or cut off from close relationships leads to negative consequences for the self and others: detrimental social behavior (increased antisocial behavior and decreased prosocial behavior) and self-defeating acts, both in the laboratory and in the society at large. These predictions are based on the theory that the need to belong is a fundamental human motivation (Baumeister and Leary, 1995). Studies 1-5 examine how three laboratory manipulations of belongingness and two questionnaire measures influence antisocial versus prosocial behavior (cheating, cooperation, aggression, and helping). Studies 6-10 use the same manipulations and measures to study the connection between belongingness and self-defeating acts (failure to persevere, risk-taking, refusing health information, and binge eating). Study 11 aims to discover which personality types react to impaired belongingness with anger versus anxiety. Study 12 attempts to find the belongingness effect in the larger society, demonstrating that national statistics relevant to belongingness correlate with those measuring antisocial and self-defeating behaviors. Pilot data from two experiments show that low belongingness leads to aggression (an antisocial behavior) and binge eating (a self- defeating act).
