The demotivating effect of social exclusion: An experimental test of a psychosocial model on the development of negative symptoms in psychosis.

The impairment in social functioning of patients with psychotic disorders is mainly driven by motivational negative symptoms with a widely unknown etiology. Building on the well-confirmed link between specific social risk factors and psychosis, the current study tested the postulated effect of immediate social exclusion on the development of motivational negative symptoms and the association of repeated social exclusion experiences with demotivating beliefs in a community sample (N = 84). Repeated social exclusion experiences and demotivating beliefs were assessed at baseline. We randomized the participants to either an exclusion or an inclusion condition of a virtual ball tossing game. Motivation and anticipatory pleasure were measured before and after the manipulation via self-report and via a behavioral effort paradigm. We found a significant multivariate effect of social exclusion on self-reported motivation (F(4,79) = 4.25, p < .01, η2 = .18), but not on behavioral effort (F(1,82) = 1.24, p = .27, η2 = .02). Repeated social exclusion was significantly associated with demotivating beliefs (r = .58, p < .01) and negative symptoms (r = .43, p < .001). Our findings support the notion that reduced motivation, anticipatory anhedonia and demotivating beliefs can be understood as motivational and cognitive consequences of social exclusion. We also discuss the implications for psychological interventions and for further research on the etiology of negative symptoms.