Single-trial ERP analysis reveals facial expression category in a three-stage scheme

• Published in: Brain research Vol. 1512; pp. 78 - 88
• Main Authors: Zhang, Dandan, Luo, Wenbo, Luo, Yuejia
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 28.05.2013; Elsevier
• Subjects: Adult; Analysis of Variance; Behavioral psychophysiology; Biological and medical sciences; Brain Mapping; Discrimination (Psychology) - physiology; Electroencephalography; Electrophysiology; Emotions - physiology; Event-related potential; Evoked Potentials - physiology; Facial Expression; Female; Fundamental and applied biological sciences. Psychology; Humans; Male; Neurology; Pattern Recognition, Visual - physiology; Photic Stimulation; Predictive Value of Tests; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Reaction Time; Reproducibility of Results; Single-trial categorization; Three stages; Young Adult; Event-related potential; Single-trial categorization; Three stages; Facial expression; Human; Affect affectivity; Scheme; Central nervous system; Electrophysiology; Cognition; Emotion emotionality; Encephalon; Visual stimulus; Face; Categorization; Event evoked potential
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/j.brainres.2013.03.044

Abstract Emotional faces are salient stimuli that play a critical role in social interactions. Following up on previous research suggesting that the event-related potentials (ERPs) show differential amplitudes in response to various facial expressions, the current study used trial-to-trial variability assembled from six discriminating ERP components to predict the facial expression categories in individual trials. In an experiment involved 17 participants, fearful trials were differentiated from non-fearful trials as early as the intervals of N1 and P1, with a mean predictive accuracy of 87%. Single-trial features in the occurrence of N170 and vertex positive potential could distinguish between emotional and neutral expressions (accuracy=90%). Finally, the trials associated with fearful, happy, and neutral faces were completely separated during the window of N3 and P3 (accuracy=83%). These categorization findings elucidated the temporal evolution of facial expression extraction, and demonstrated that the spatio-temporal characteristics of single-trial ERPs can distinguish facial expressions according to a three-stage scheme, with “fear popup,” “emotional/unemotional discrimination,” and “complete separation” as processing stages. This work constitutes the first examination of neural processing dynamics beyond multitrial ERP averaging, and directly relates the prediction performance of single-trial classifiers to the progressive brain functions of emotional face discrimination.