Int J Psychophysiol 2008 Oct 22;70(1):50-62. Epub 2008 May 22.
Catholic University of Louvain, 10 Place C. Mercier, 1348 Louvain-la-Neuve, Belgium.
Objective: Recent studies have shown that alcoholism is characterized by a deficit in the processing of emotional facial expressions (EFE), and that this deficit could be "emotion specific". The present study explored the hypothesis that there is a specific deficit for the EFE of anger compared to another negative emotion (disgust). Moreover, on the basis of event-related potentials (ERPs), this study aimed at determining the locus of this deficit in the information-processing stream.
Methods: Fifteen patients suffering from alcoholism and fifteen matched healthy controls took part in the study, which used a "modified emotional" oddball paradigm. ERPs were recorded in response to repetitions of a particular facial expression (i.e. anger) and in response to two deviant (rare) stimuli obtained by a morphing procedure, one depicting the same emotion as the frequent stimulus, the other depicting a different emotion (i.e. disgust). The participants' task was to press a key as soon as they spotted the deviant stimulus.
Results: Behavioural data showed an absence of categorical perception effect for anger (but not for disgust) stimuli among alcoholic patients. Moreover, electrophysiological data revealed that alcoholism is associated with an impaired processing of anger at the attentional level (N2b/P3a complex), extending to the decisional level (P3b).
Conclusion: This study demonstrated disturbed processing of anger in alcoholism, at behavioural and electrophysiological levels. These preliminary results strengthen the proposition of a specific deficit for anger, and localize its possible origin to the attentional level (N2b/P3a complex) of the information processing stream. The clinical implications of these results are discussed.