| The gaze direction of others’ eyes is important social information.The process of gaze direction mainly includes gaze perception and attention orientation triggered by gaze direction.Previous studies have found bias in the perceptual process of others’ gaze direction,which is affected by facial expression.The left bias of gaze under fearful facial expression is closely related to the brain activity of the right hemisphere.A large number of magnetic resonance imaging and near-infrared imaging studies affirmed that the brain activity of the right superior temporal sulcus is related to gaze direction perception and gaze cue effect.However,there is still a lack of direct evidence to prove the relation between the right superior temporal sulcus and gaze direction perception and gaze cue effect.Therefore,this study used transcranial direct current stimulation（t DCS）technology to investigate whether t DCS anodal/cathodal stimulation of the right superior temporal sulcus can effectively regulate the left bias of individuals’ gaze perception and gaze cue effect.The study contained four experiments.Experiments 1 and 2 investigated the effect of t DCS anodal/cathodal stimulation of the right superior temporal sulcus on the left bias of gaze perception of fearful faces.Experiments 3 and 4 investigated the effect of t DCS anodal/cathodal stimulation of the right superior temporal sulcus on gaze cue effect.In Experiment 1,t DCS cathode stimulation was used on the right superior temporal sulcus brain area.The subjects were instructed to judge the gaze direction under four facial expressions,in which the gaze direction changed continuously in horizontal.The number of times that subjects judged the face looked to the left was recorded,and the point of subjective equivalence（PSE）was employed as the dependent variable.The results showed that the subjects were more inclined to perceive the gaze direction of fearful expression as looking to their left side,and were not affected by t DCS cathode stimulation.In Experiment 2,t DCS anodal stimulation was used on the right superior temporal sulcus.The subjects completed the same experimental task as Experiment 1.The results showed that in sham condition,subjects were more inclined to perceive the gaze direction of fearful expression as looking to their left side,while in anodal condition,there was no such left bias.In Experiment 3,t DCS cathodal stimulation was used on the right superior temporal sulcus.The subjects were instructed to complete the cueing task,containing two types of cues: arrow and gaze.The reaction time was recorded and used as the dependent variable.The results showed that the cueing effects of both gaze cue and arrow cue were robust,and were not affected by t DCS cathode stimulation.In Experiment 4,t DCS anodal stimulation was used on the right superior temporal sulcus.The subjects completed the same task as Experiment 3.The results showed that the gaze cueing effect of the t DCS anodal condition was significantly smaller than that under the sham condition.The results of this study showed that:（1）gaze perception is affected by facial expression,and there is a left bias in the gaze perception of fearful expression;（2）t DCS anodal stimulation of the right superior temporal sulcus weakened the left bias of gaze perception of fearful expression;（3）gaze cue and arrow cue showed a robust cueing effect;（4）t DCS anodal stimulation of the right superior temporal sulcus weaken the gaze cueing effect,but did not affect the arrow cueing effect. |
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