Inhibitory Control and Reactive Aggression Under Heat Stress

Environmental stressors such as heat are increasingly relevant for understanding behavioral regulation. This study investigated how thermal stress affects inhibitory control and reactive aggression, and whether these effects are moderated by individual differences such as trait impulsivity. Sixteen participants completed three lab sessions in a temperature-controlled sauna chamber (23°C, 36°C, 45°C), performing a Stop Signal Task (SST) and a reactive aggression task (RC-RAGE) in each session. We hypothesized that higher temperatures would impair inhibitory control and increase costly, reactive aggression, particularly among individuals high in trait impulsivity. Results showed that motor impulsivity predicted longer stop-signal reaction times (SSRTs), especially under moderate heat. In the RC-RAGE task, participants with higher motor impulsivity were more likely to retaliate even when retaliation caused a monetary cost. However, neither SST nor aggression outcomes showed consistent main effects of temperature, and trait-by-condition interactions were limited, possibly due to floor effects and reduced behavioral variability under high heat. Exploratory analyses revealed no significant differences in anger endorsement across temperature conditions. These findings suggest that trait impulsivity, particularly motor impulsivity, plays a central role in both cognitive and affective regulation, and that moderate heat stress may amplify these trait effects. The study underscores the importance of examining trait-by-environment interactions and highlights challenges in behavioral measurement under thermal extremes.