Vagal Activity Is Associated With Intuitive Decision‐Making in Men Under Stress‐Free Conditions but Not Following a Stressor

While stress seems to increase risk-taking, the mechanisms involved remain unclear. The Somatic Marker Hypothesis, which postulates that somatic markers (intuitive signals) indexed by skin conductance responses (SCR) advantageously guide decisions, allows investigating the underlying mechanisms. The cerebral integration of somatic markers is thought to occur via the vagus nerve, whose activity is modulated in stressful situations. This study tested whether vagal activity moderates the ability for somatic markers to guide decision-making following stressful and control conditions. As sex differences have been observed in decision-making, they were also considered as a possible moderator. Young adults (n = 111; 57 women) were randomly assigned to the Trier Social Stress Test or a control condition before completing the Iowa Gambling Task. Cardiac vagal activity, indexed by heart rate variability (HRV), and SCR were recorded during the task. Bayesian logistic multilevel modeling revealed that SCR was predictive of decision-making only for men in the control condition with high cardiac vagal activity. More specifically, when men with high HRV experienced a decrease in SCR relative to their mean, their likelihood of choosing a risky deck decreased at the end of the task. Although these findings were not observed in women, they suggest that vagal activity may promote intuitive decision-making following non-stressful conditions, whereas stress exposure may impede these beneficial effects.