An electrophysiological investigation of attentional bias in a PTSD population.

Objective: Evidence relying on probe detection tasks suggests that anxious individuals exhibit an enhanced selective attentional bias toward emotional or threating stimuli, characterized by attentional vigilance or avoidance of threat. Method: Amplitude of P100 and P300 event-related potentials and behavioral measures of target detection were assessed during presentation of a dot-probe task in 18 posttraumatic stress disorder patients and 18 healthy controls to elucidate the effects of attentional bias toward threatening facial expressions. Results: Perceptual (P100) processing of threat-face pairs revealed no evidence of attentional bias in posttraumatic stress disorder (PTSD) patients. PTSD patients exhibited larger P100 and P300 amplitude to probes replacing neutral rather than angry faces, indicating an increased allocation of early perceptual and later strategic processing away from anger-related stimuli. Conclusion: The present study provided no support for facilitated engagement in this sample of patients. Possible interpretations of the results related to differential processing of target probes replacing angry-neutral face pairs are discussed.