Impact of task demands on the neural processing of facial emotions

The Early Posterior Negativity (EPN) (~250-350ms post-stimulus) ERP component is a known marker of facial emotion processing however whether the face-sensitive N170 (~100-200ms post-stimulus) component is also sensitive to emotional faces remains debated. Possible causes for the previous inconsistent results are the use of different tasks involving varying degrees of attention to the emotional faces and the lack of control of point-of-gaze on the faces. We investigated whether emotion sensitivity of the N170 and EPN varied as a function of task in a sample of 33 participants. ERPs were recorded in response to the same fearful, joyful, or neutral faces during an explicit emotion discrimination task, a gender discrimination task, and an oddball detection (flower detection) task. Task order was counterbalanced across participants. Using an eye-tracker, fixation was restricted to the nose (i.e., centre of mass) where holistic processing is maximal. Results revealed N170 modulation by emotion with larger responses for fearful than happy or neutral faces in all tasks. As predicted, the EPN was modulated by emotion with larger responses for fearful compared to neutral faces. The EPN was also modulated by task with largest responses during the gender discrimination task, followed by the emotion discrimination task and smallest responses for the oddball detection task. Results suggest that when conditions for holistic processing are maximized with fixation to the centre of mass, the N170 is sensitive to fear irrespective of the degree of attention to the face placed by task demands. Meeting abstract presented at VSS 2015