Abstract
BACKGROUND: Acute stress has complex effects on executive function and social behavior; however, the direction of these effects is inconsistent across studies, and the underlying neural mechanisms remain poorly understood. This study investigated the behavioral and neural effects of acute stress on executive function and dyadic cooperation and their relationships. METHODS: Eighty-six healthy male undergraduates (18-25 years) were randomly assigned to stress (n = 44; Trier Social Stress Test for Groups [TSST-G]) or control groups (n = 42; placebo TSST-G). The participants completed executive function tasks (3-back, Go/Nogo, Stroop, and task-switching) and cooperative button-pressing tasks pre- and postintervention, with a counterbalanced order. Functional near-infrared spectroscopy (fNIRS) was performed simultaneously. RESULTS: Stress impaired the practice-induced improvement in 3-back accuracy observed in the control group, although it did not significantly affect other performance metrics. During the 3-back, Stroop, task-switching, and cooperative tasks, increased and decreased prefrontal cortex (PFC) activation from baseline to postintervention were observed in the stress and control groups, respectively. Furthermore, greater bilateral dorsolateral PFC (DLPFC) interbrain synchronization (IBS) changes during the cooperative task were observed in the stress group. Cognitive flexibility and cooperation were positively linked both behaviorally and neurally. CONCLUSIONS: TSST-G-induced stress disrupted the learning-related enhancement of working memory; however, response inhibition, interference control, cognitive flexibility, and cooperative performance were preserved. The concurrent observation of trends toward increased neural activation and IBS under stress is compatible with, but does not prove, potential compensatory mechanisms. The identified neural and behavioral correlations point to a potential connection between executive and social processes under stress. We tentatively frame these exploratory observations within the "Executive-Social Function Coupling Hypothesis" as a heuristic model for future research. The implications of these preliminary findings are discussed.