Is freezing an adaptive reaction to threat? Evidence from heart rate reactivity to emotional pictures in victims of war and torture

The influence of past traumatic experiences on the defense cascade in response to affective pictures was examined in survivors of war and torture. Trauma-exposed refugees with and without Posttraumatic Stress Disorder (PTSD) as well as healthy individuals viewed 75 pictures that varied in emotional content. Heart rate (HR) was recorded during the flickering stimulation of affective pictures in the context of a steady-state experiment. Whereas healthy controls showed the typical orienting response to aversive stimuli, PTSD patients reacted with an almost immediate increase in HR toward unpleasant pictures. Trauma-exposed participants without PTSD showed an indiscriminate orienting response regardless of picture category. The present findings argue for a faster flight/fight response to threatening cues in PTSD. In contrast, trauma-exposed controls seem to exhibit a state of permanent alertness toward a wide range of stimuli.