Electrophysiological Findings of Visual Attention Bias Away from Angry Faces in Patients with PTSD

Evidence from visual probe detection tasks suggests that anxious individuals exhibit biased (enhanced) selective attention to threat stimuli, such as angry and fearful faces. Attentional bias to threatening stimuli has been characterized by (1) facilitated attention to stimuli (vigilance), (2) difficulty disengaging attention away from stimuli, or (3) attentional avoidance of stimuli. The current study used event-related potentials (ERP) and behavioural performance measures to examine the effects of attentional bias towards ecologically threatening stimuli (emotional faces) in 18 post-traumatic stress disorder (PTSD) patients and 18 healthy controls during a dot probe task. Behavioural measures of target detection and the amplitude and latency of early (P100, N100) and late (P200, P300) ERPs were assessed during presentation of face pair displays and target probes. Processing of threat-face pairs did not reveal evidence of attentional bias in PTSD patients. Perceptual (P100) and cognitive processing (P300) of target probes following angry-neutral face pairs revealed evidence of attentional avoidance in the patient group. The P100 and P300 ERPs revealing avoidance patterns to angry-neutral face pairs also correlated with severity of PTSD symptoms and revealed an inverse correlation with severity of depression, respectively. The ERP results time-locked to the target-probe paralleled findings with performance accuracy. The present study provided no support for facilitated engagement to threatening visual stimuli in this sample of patients, instead showing that PTSD patients may exhibit an avoidance pattern to threatening stimuli that may be controlled by strategic mechanisms occurring at later stages of information processing. Meeting abstract presented at VSS 2013