Neural mechanisms of intergroup exclusion and retaliatory aggression

Abstract

Aggression occurs frequently and severely between rival groups. Although there has been much study into the psychological and socio-ecological determinants of intergroup aggression, the neuroscience of this phenomenon remains incomplete. To examine the neural correlates of aggression directed at outgroup (versus ingroup) targets, we recruited 35 healthy young male participants who were current or former students of the same university. While undergoing functional MRI, participants completed an aggression task against both an ingroup and an outgroup opponent in which their opponents repeatedly provoked them at varying levels and then participants could retaliate. Participants were then socially included and then excluded by two outgroup members and then completed the same aggression task against the same two opponents. Both before and after outgroup exclusion, aggression towards outgroup members was positively associated with activity in the ventral striatum during decisions about how aggressive to be towards their outgroup opponent. Aggression towards outgroup members was also linked to greater post-exclusion activity in the rostral and dorsal medial prefrontal cortex during provocation from their outgroup opponent. These altered patterns of brain activity suggest that frontostriatal mechanisms may play a significant role in motivating aggression towards outgroup members.

Similarity in Neural Representations of Immorality and Harm

“…Potential participants were recruited from the Richmond VA community (n = 30) and an introductory psychology subject pool (n = 5) via flyers and online advertisements. We recruited only men because this study was part of a broader project on the neural bases of men's psychopathic aggression and morality (see Lasko et al, 2022). We used an online screening questionnaire, which assessed the following additional exclusionary criteria that ensured participant safety and MRI data quality: age outside the range of 18 to 35, body mass index above 35, claustrophobia, color blindness, mental or neural pathology, metallic objects in the body, non-right-hand dominance, prior head trauma, and current psychoactive medication use.…”