Depressive Tendency Biases Ensemble Perception Of Emotional Faces

Proper processing of facial expressions is crucial for individuals to perceive others’ emotional states,intention,motivation and so on.Especially when people meet a crowd of faces at a time,they can always extract the average emotion of the crowd rapidly and accurately,which is called ensemble perception.Previous studies showed that depressed people have an impaired ability in encoding single facial expression.However,it is largely unknown how depression or depressive tendency affects the perception of average emotion of multiple faces.To address this question,the current study conducted three behavioral experiments in total.We investigated whether depressive tendency would affect the explicit or implicit ensemble perception of emotion when attentional resources are sufficient or not,by comparing the ensemble perception of emotion between depressive tendency group(DTG)and healthy group(HG).Experiment 1a was exploratory.Sets of 4 emotionally varying faces(from angry to happy)were presented for 2000 ms,followed by a single test face.Participants were instructed to judge whether a test face was angrier than the mean emotion of the preceding set(conducted ensemble perception consciously).Results showed that the point of subjective equality(PSE)of DTG was more biased towards anger and their accuracy of explicit ensemble perception was lower compared with HG.Based on Experiment 1a,Experiment 1b shortened the exposure time of stimuli sets to 50 ms.The aim was to investigate whether depressive tendency would still affect the explicit ensemble perception when the processing time of perception was scarce.Results found that DTG and HG did not show any difference in both bias and accuracy of ensemble emotion.Experiment 2 further investigated whether depressive tendency would affect ensemble perception implicitly.The exposure time of stimuli sets was manipulated in two blocks(lasted for 50 ms and 2000 ms,respectively).Sets of 4 faces with varying emotionality were presented for 2000 ms,then participants were required to determine whether the test face was a member of the preceding set.Ensemble perception occurred when “mean emotion” faces were deemed as member faces mistakenly(conducted ensemble perception automatically).Results indicated that DTG showed less automatic perception of ensemble emotion than HG,but only when the exposure time was 2000 ms.In conclusion,the current research demonstrates that depressive tendency can bias ensemble coding for emotional faces at both explicit and implicit levels.High levels of depressive tendency are responsible for the poorer performance in ensemble perception and the tendency to negatively estimate ensemble emotions.However,the bias appears only when exposure time is sufficient.The findings of our study reveal the perceptual characteristics of individuals with depressive tendencies in front of face crowds and may shed light on theories regarding emotional processing in depression from the perspective of ensemble perception.