Encoding of Emotional Facial Expressions in Direct and Incidental Tasks: An Event-Related Potentials N200 Effect

Özet

Emotional face encoding processes in 2 types of tasks (direct and incidental) were explored in the current research through electroencephalographic (ERPs) and behavioral (response) measures. In Experiment 1 (incidental task) ERP correlates of 21 subjects were recorded when they viewed emotional (anger, sadness and happiness) or neutral facial stimuli. An emotion-specific cortical variation was found, a negative deflection at about 200 ms poststimulus (N2 effect). This effect was sensitive to the perceived emotional value of faces, since it differentiated negative high arousal (i.e., anger) from low arousal (i.e., sadness) or positive (happiness) emotions. Moreover, a specific cortical site (parietal) was activated by emotional faces but not by neutral faces. In Experiment 2 (20 subjects) a direct encoding task (emotion comprehension) was provided. We explored whether encoding for emotional faces relies on a single neural system irrespective of the task (incidental or direct), or whether it is supported by multiple, task-specific systems. The same difference previously observed between emotions, as a function of arousal and valence, was found in the direct condition. Nevertheless, we found differences in the cortical distribution (parietal for the incidental task; central and parietal for direct task) and lateralization (right-distribution for the negative emotions in the direct task) of the N200 on the scalp due to different types of task. The cognitive significance of these ERP variations is discussed.