Stress Response and Facial Trustworthiness Judgments in Civilians and Military

We tested the hypothesis that, either through training or selection, military personnel is more resilient to stress than civilians, as indicated by several subjective and physiological measures. In addition, we examined the effect of stress on the perceived trustworthiness of faces in these two groups. Stress was induced in 45 civilian participants and 45 army participants through the Sing-a-Song Stress Test (SSST). In this paradigm seven neutral sentences are presented, each followed by a 60-s interval. An eighth sentence asks participants to sing a song aloud after the next (eighth or stress) interval. Participants rated the trustworthiness of five neutral faces, both before and after the SSST. Pupil size, heart rate, and skin conductance were adopted as physiological stress correlates. Stress response was calculated as the difference between the mean values over the last neutral interval and the stress interval. Subjective stress ratings were obtained before and after the SSST. The baseline levels of all physiological and subjective measures were the same in the army and civilian groups, while all measures showed a significant increase following the stressor. However, compared with the civilian group, army participants reported significantly less stress and showed significantly attenuated heart rate and skin conductance responses to the SSST. These results indicate higher stress resilience in the army compared with the civilian group. In addition, we found that perceived facial trustworthiness decreased after presentation of the stressor, suggesting that the effect of a stressor can influence in principle unrelated social judgments based on facial information. © The Author(s) 2017.