Emotional facial reactions after sleep restriction: any hints for automaticity?
Eisenbarth, H.1, Haas, J.2, Alpers, G. W.3, Popp, R.2, Schwarz, J.2, and Zulley, J.2
1Department of Forensic Psychiatry, University of Regensburg; 2Department of Psychiatry, University of Regensburg; 3Department of Psychology I, University of Wuerzburg
Facial muscles reactions in response to presented emotional facial expressions are assumed to be automatic. However, there is evidence that these reactions depend on cognitive load. As restricted sleep has been shown to reduce cognitive performance, such a paradigm offers the opportunity to vary cognitive load. This study focuses on the effects of sleep restriction and hence reduction in cognitive performance on facial reactions.
25 students with normal sleep habits completed an emotion categorizing task after a night of normal sleep (8h) and after another night of restricted sleep (4h). EMG of zygomaticus and corrugator was measured while participants had to react compatibly or incompatibly with one of the muscles to positive vs. negative emotional slides. Attentional tasks were administered to control for sleep restriction effects. We expected that facial reactions are decelerated, but the advantage of valence compatible compared to incompatible reactions would persist. Implications of the results for the hypotheses of automaticity of facial reactions are discussed.