Facial trustworthiness perception bias elevated in individuals with PTSD compared to trauma exposed controls.

Posttraumatic stress disorder (PTSD) research has focused largely on fear processing. However, interpersonal trauma exposure can also impact interpersonal functioning and the perception of the trustworthiness of others. The present study examined facial perceptions of fearfulness and trustworthiness in individuals with PTSD (n=29), trauma-exposed without PTSD (n=19), and healthy controls (n=18). The PTSD group was hypothesized to exhibit a bias to perceive more fear and untrustworthiness in faces relative to controls. Participants rated the level of fearfulness or trustworthiness of faces that were parametrically morphed along a fear or trustworthiness dimension. The PTSD group was biased to perceive faces as more trustworthy compared to the trauma-exposed healthy controls, yet there were no differences between groups in fear processing. A trustworthiness bias in PTSD may represent a vulnerability factor. Conversely, lower trustworthiness perception may represent a protective disposition in trauma-exposed individuals who do not develop PTSD. Differences in the perception of trustworthiness may be an aspect of social perception that is independent of the fear processing abnormalities observed in PTSD.