Processing of facial emotional expression: spatio-temporal data as assessed by scalp event-related potentials

Event-related potentials (ERPs) were recorded in 10 adult volunteers, who w ere asked to view pictures of faces with different emotional expressions, i .e. fear, happiness, disgust, surprise and neutral expression [Ekman, P. & Friesen, W.V. (1975). Pictures of Facial Affect. Consulting Psychologist Pr ess, Palo Alto, CA]. ERPs were recorded during two different tasks with the same stimuli. Firstly, subjects were instructed to pay attention to the ge nder of the faces by counting males or females. Secondly, they had to focus on facial expressions by counting faces who looked surprised. The classica l scalp 'face-related potentials', i.e. a vertex-positive potential and a b ilateral temporal negativity, were recorded 150 ms after the stimulus onset . Significant differences were found, firstly between late-latency ERPs to emotional faces and to neutral faces, between 250 and 550 ms of latency and , secondly, among the ERPs to the different facial expressions between 550 and 750 ms of latency. These differences appeared only during the expressio n discrimination task, not during the gender discrimination task. Topograph ic maps of these differences showed a specific right temporal activity rela ted to each emotional expression, some particularities being observed for e ach expression. This study provides new data concerning the spatio-temporal features of facial expression processing, particularly a late-latency acti vity related to specific attention to facial expressions.