Clarifying the NAP Effect and the Role of Dispositional Factors: Behavioural and Electrophysiological Investigations

Researchers using the negative affective priming (NAP) paradigm favour a dispositional argument for the negative ruminatory cycle in depression despite some evidence supporting an affect-based explanation. Additionally, the cognitive mechanisms underlying the task are poorly understood. To examine these questions directly, a modified version of the NAP task, that dissociates the priming effects of positive and negative words, was implemented in two experiments. The first experiment tests the contribution of disposition (as measured by the NEO-PI-R depression subscale) versus symptom severity (as measured by the BDI-II) to NAP scores. Compared to low BDI-II scorers, high BDI-II scorers showed a larger NAP effect for negative words, and a smaller NAP effect for positive words. However, there were no significant differences between high and low scorers on the NEO-PI-R depression subscale. This suggests that current severity of symptoms and not dispositional factors influence the NAP effect more strongly. The second experiment used event related potentials (ERPs) to determine the cognitive processes involved in the NAP task prior to a participant’s response. The results showed that prior presentation of irrelevant emotion words significantly affected the brain response to subsequent task-relevant emotion words. Thus, on ignored repetition (IgnRep) trials positive voltage modulations were observed both early, over frontal scalp (between 190-260ms) and late, primarily over posterior scalp (between 500-700ms). Interestingly, IgnRep trials for negative words were associated with the early frontal effects, suggesting an early, implicit attentional bias to negative material, while IgnRep trials for positive words were associated with the later positivity, indicating more conscious processing of positive material. Results are discussed in terms of current theories of the processes involved in the NAP effect.