Impaired Perceptual Processing Of Facial Expression Categorization In Social Anhedonia

Aim:Social anhedonia is characterized by reduced desires for social affiliation and a diminished capacity to experience pleasure from social interaction.Indeed,social anhedonia is a detectable personality trait in general populations and also a transdiagnostic construct in clinical samples including major depression disorders and schizophrenia.Characterizing neural substrates underlying social anhedonia in processing emotionally social information is of paramount importance and can shed lights on the prevention and intervention of relevant psychiatric diseases.Differences in neural processing of emotional facial expressions provide a starting point for characterizing abnormalities associated with social anhedonia.Given that previous evidence has suggested positive and negative facial expressions are related to distinct perceptual strategies,it is possible that the abnormality of emotional happy expression processing in social anhedonia may originate from altered perceptual processing.The possibility has not yet been directly assessed.Here,the current ERP study aimed to investigate the perceptual processing of the categorization advantage of happy over sad faces in social anhedonia with a non-clinical sampleMethods:A group of 53 volunteers were invited into high social anhedonia(HSA)group and low social anhedonia(LSA)group based on their scores on the Chinese version of the Revised Social Anhedonia Scale administered in a sample pool of 507 university students.The participants completed a facial expression categorization task during which they were instructed to classify facial expressions(happy,neutral,sad),irrespective of face orientations(upright,upside-down).We used schematic face stimuli to control for low-level physical differences between the types of facial expressions and face inversion to manipulate the perceptual processing(configural vs.featural).Participants also completed a range of measurements,including the Anticipatory and Consummatory Interpersonal Pleasure Scale(ACIPS),the Temporal Experience of Pleasure Scale(TEPS),the Snaith-Hamilton Pleasure Scale(SHAPS),the Beck Depression Inventory(BDI-?)and the social Interaction Anxiety Scale(SIAS).The EEG signals were amplified using a Neuroscan SynAmp2 amplifier and were preprocessed and analyzed using MATLAB and EEGLAB toolbox.A repeated-measures analysis of variance(ANOVA)was used for ERP and behavioral data in SPSS v23(IBM,Armonk,NY).The present ERP study examined the categorization advantage of happy over sad faces in social anhedonia with a non-clinical sample by combining behavioral performance with the ERP components(i.e.,the P1,N170 and P2)associated with perceptual processing of facial expressionsResults:1.HSA group scored significantly lower than LSA group on the ACIPS(p<.001)and TEPS(p=.033);HSA group scored significantly higher than LSA group on the RSAS(p<.001)and BDI-?(p=.033);Both groups were comparable on the SHAPS and SIAS(ps>.05)2.For behavioral performance,a significant interaction effect between expression and orientation emerged,F(2,100)=52.97,p<.001,?p2=.51.Post hoc comparisons revealed that happy faces(587±79 ms)were identified faster than sad faces(607±83 ms)across both groups,which emerged only in upright orientation(p=.007)3.An ANOVA on P1 latencies and amplitudes revealed no main effects or interactions involving group(ps>.060).4.For N170 latencies,there was a significant three-way interaction among group,expression,and orientation,F(2,100)=3.38,p=.039,?p2=.06.Post hoc comparisons revealed that LSA group exhibited a faster N170 for happy than for sad faces only in upright orientation(ps<.05).HSA group did not show any expression effect on N170 latencies across face orientations(ps>.7).For N170 amplitudes,there was a significant three-way interaction among expression,orientation,and group,F(2,100)=3.18,p=.046,?P2=.06.Post hoc comparisons revealed that LSA group showed a larger N170 in response to sad faces than happy only in upright orientation(p=.007).HSA group exhibited no difference of N170 amplitudes between happy and sad faces across face orientations(ps>.050).5.For P2 amplitudes,there was a significant three-way interaction among expression,orientation,and group,F(2,100)=3.67,p=.030,?p2=.07.Post hoc comparisons revealed that HSA group exhibited a reduced P2 for happy faces relative to sad faces only in upright orientation(p<.001).For LSA group,the amplitude of the P2 was comparable between happy and sad faces across orientations(ps>.2)Conclusions:1.Both HSA and LSA groups showed a normal categorization advantage of happy faces at the behavioral level2.HSA individuals showed a deficit in the categorization advantage of happy over sad faces during the early perceptual stage of face processing,which may be further attributable to the dysfunctional configural processing in this sample3.HSA relative to LSA individuals showed a delayed neural discrimination between happy and sad faces.