From Reopening to the New Normal: The Impact of COVID-19 on Intergroup Conflict Behaviour.

Intergroup conflict threatens human survival and social development, often triggered by environmental changes such as pandemics. Understanding individual behaviour in intergroup conflict during crises is critical for explaining shifts in intergroup relations. Using COVID-19 as a major environmental threat, the present study combined behavioural experiments and questionnaire measures with 1167 participants from 34 Chinese provinces across three stages: before the pandemic, after the reopening policy was announced and after the pandemic ended. We examined temporal changes in self-interest, ingroup cooperation and outgroup aggression, along with the moderating role of cultural values. Results showed that shortly after reopening, self-interest and ingroup cooperation first decreased and then increased, patterns moderated by interdependent self-construal. Conversely, outgroup aggression first increased and then decreased, jointly influenced by cultural tightness-looseness and infection status. Across the broader pandemic stages, self-interest remained higher and outgroup aggression remained lower than the pre-pandemic baseline, while cultural values exerted moderating effects only at specific stages. These findings suggest that pandemic-related environmental threats do not simply increase cooperation or conflict but reshape individuals' trade-offs among personal, ingroup and outgroup interests. This study provides psychological evidence for understanding intergroup conflict behaviour under environmental threat and offers implications for crisis governance.