Aggressive intentions after social exclusion and their association with loneliness.

Both social exclusion and loneliness are aversive experiences that can lead to hostile behavioral reactions, including aggressive behavior. This study aimed to assess whether a social exclusion scenario in the subject's imagination elicits aggressive reactions towards an excluding person as measured with the hot sauce paradigm. Furthermore, we studied the effect of loneliness on such reactions. In total, 251 subjects (67.7% female; mean age 27.3 ± 9.3 years) participated in this study which was based on an online survey. After trait loneliness was assessed with the UCLA Loneliness scale at baseline, two imaginary scenarios were presented in randomized order, i.e., an exclusion condition (with one of two working colleagues excluding the participant from a social activity) and an inclusion condition (without exclusion). Following each scenario, participants had the task to allocate the amount of hot sauce to each colleague that they find appropriate. Participants distributed significantly more hot sauce to the excluder than to the includers. The amount of hot sauce was significantly correlated with loneliness for all includer interactions (i.e., after the inclusion as well as the exclusion scenario), but not for the interaction with the excluder. Our results support the hypothesis that social exclusion elicits aggressive behavior. Interestingly, the experience of loneliness seems to be associated with an increase in aggressive behavioral tendencies or a lack of their inhibition. The cognitive and/or emotional processes underlying the interplay between social exclusion, loneliness and aggression should be a focus of future research.