Mood effects on the ERP processing of emotional intensity in faces: a P3 investigation with depressed students.

This study examined mood-relevant emotion processing in depression using event-related potentials (ERPs). Cognition in depression has been characterized as having attention and memory biases for negative (or mood relevant) information and away from positive (or mood incongruent) information, however, the time course and specificity of this processing during the perception of emotional expressions is not well known. In order to index specific information processing stages a visual oddball task with facial stimuli was utilized, with neutral expressions as the standard and targets varying on valence (happy and fear) and intensity (40%, 70% or 100% emotive) dimensions. Participants were 36 university students grouped according to their BDI-II scores; 18 non-depressed controls (BDI-IIor=15, M=25.5), age- and sex-matched between groups. Mixed model ANOVAs revealed interactions between control and depressed participants with happy and fearful stimuli showing significantly reduced P3 amplitudes and P3 latencies for happy faces as well as significantly delayed P3 latencies specifically for 40% happy faces in depressed participants. These findings are interpreted as evidence for a diminished cognitive processing ability during emotion discrimination for low-intensity mood incongruous (happy) faces in depression.