Threat modulation of visual search efficiency in PTSD: A comparison of distinct stimulus categories.

Although an attentional bias for threat has been implicated in posttraumatic stress disorder (PTSD), the cues that best facilitate this bias are unclear. Some studies utilize images and others utilize facial expressions that communicate threat. However, the comparability of these two types of stimuli in PTSD is unclear. The present study contrasted the effects of images and expressions with the same valence on visual search among veterans with PTSD and controls. Overall, PTSD patients had slower visual search speed than controls. Images caused greater disruption in visual search than expressions, and emotional content modulated this effect with larger differences between images and expressions arising for more negatively valenced stimuli. However, this effect was not observed with the maximum number of items in the search array. Differences in visual search speed by images and expressions significantly varied between PTSD patients and controls for only anger and at the moderate level of task difficulty. Specifically, visual search speed did not significantly differ between PTSD patients and controls when exposed to angry expressions. However, PTSD patients displayed significantly slower visual search than controls when exposed to anger images. The implications of these findings for better understanding emotion modulated attention in PTSD are discussed.