Electrophysiological indicators of emotion processing biases in depressed undergraduates.

It has been proposed that depressed individuals are biased towards and have more difficulty disengaging from negative information once it has been made salient (e.g. Joormann, J., 2004. Attentional bias in dysphoria: the role of inhibitory processes. Cognition & Emotion 18 (1), 125-147). The current study examined whether attention- and inhibition-related brain potentials were sensitive to both of these phenomena in depression using an affective go/no-go paradigm. Eighteen undergraduates who scored high on the Inventory to Diagnose Depression (IDD; Zimmerman, M., Coryell, W., 1987. The inventory to diagnose depression (IDD): a self-report scale to diagnose major depressive disorder. Journal of Consulting and Clinical Psychology 55 (1), 55-59) and 19 who scored low on the IDD completed the experiment. Results indicated that across all trials, subjects high on depressive symptomatology exhibited larger P3s in response to negative compared to positive stimuli. Examination of ERPs on trials uncontaminated by task-switching effects revealed larger N2s on "no-go" than "go" trials, and, specific to the depressive group, larger N2s in response to positive compared to negative stimuli. These data provide electrophysiological evidence that depressive subjects differentially categorize positive and negative emotional pictures. The P3 valence effect may help to explain difficulties inhibiting negative information seen in depression.