| Event-related brain potential data supporting the existence of a 'negativity bias' in normative affective picture processing is inconsistent. We hypothesized that, when stimuli were varied and arousal level is controlled, the effect might be a primarily exhibited by those with elevated depressive symptomatology. Nineteen undergraduates performed an affective go/no go task using arousal-equated positive and negative IAPS pictures while ERPs were collected. Following the task, depressive symptomatology was assessed. Consistent with previous studies, subjects made more commission errors for positive than negative distracters and no-go trials elicited larger P3s than go trials. The posterior P3, averaged across all correct trials, was incrementally larger for negative than for positive stimuli. Dividing our subject sample into high and low depression groups revealed that this effect was primarily driven by individuals relatively high on depressive symptomatology. These results indicate that the negativity bias, as reflected by ERPs, is a function of individual differences in state or trait affect. |
