An attentional inhibitory deficit for irrelevant information in obsessive-compulsive disorder: Evidence from ERPs

•OCD patients showed a general slowness to color-name all types of words in the emotional Stroop task.•OCD patients displayed overall larger P2 and P3 amplitudes than healthy controls.•Negative words elicited a larger P3 amplitude than neutral words independent of group.•OCD patients exhibit an attentional inhibitory deficit for task-irrelevant information.

Previous studies on attentional bias have demonstrated that patients with obsessive–compulsive disorder (OCD) have an overall longer reaction time (RT) for various stimuli. It was hypothesized that this general slowness may indicate the presence of an attentional inhibition deficit in OCD. To test the hypothesis, event-related potentials (ERPs) were recorded in 31 non-medicated OCD patients and 29 age-, handedness- and sex-matched healthy controls while they performed an emotional Stroop task (EST). Relative to the control subjects, the OCD patients had similar interference effects for negative words, but an overall longer RT and larger P2 and P3 amplitudes to all words. These results support the notion that OCD is characterized by an attentional inhibitory dysfunction for irrelevant information.