Consciousness and emotion: ERP modulation and attentive vs. pre-attentive elaboration of emotional facial expressions by backward masking

Facial stimulus processing is an important topic to explain how people comprehend affective disposition in others. The effect of attentive and pre-attentive elaboration of emotional facial expression was explored in the present research by using backward masking procedure. Specifically, unconscious mental process of emotion comprehension was analyzed: pictures presenting a happy, sad, angry, fearful, disgusted, surprised expressions were submitted to 21 subjects in both attentive and pre-attentive conditions and event-related potentials (ERPs) were registered in the two conditions. The two processes, attentive and pre-attentive, seem to be similar in their nature, since they are marked by analogous ERP deflections. In fact, two ERP effects were found, a positive (P300) deflection, maximally distributed on the parietal regions, and a negative (N200) deflection, more localized on the frontal sites. Nevertheless, some differences between the two conditions were found in terms of quantitative modulations of the two peaks. The N200 effect, ampler in attentive condition, may be considered such as an index of conscious processing of emotional faces, whereas the P3 (P3a) effect, higher in pre-attentive condition, was considered a specific marker of the automatic, unconscious process during the emotional face comprehension.