High-definition transcranial direct current stimulation facilitates emotional face processing in individuals with high autistic traits: A sham-controlled study

•Anodal HD-tDCS over the rTPJ facilitates emotional face processing.•Improved gaze behavior including increased fixation time and count of mouth AOI.•Compared with neutral faces, rTPJ is more closely associated with emotional faces processing.•Eye-tracking technology supports the effect of the HD-tDCS on facial processing. The deficit in emotional face processing is a critical impairment for individuals with high autistic traits. The temporalparietal junction(TPJ) is considered to be closely related to emotional face processing. The aim of this study was to examine the effect of highdefinition transcranial direct current stimulation (HD-tDCS) over the right temporal-parietal junction (rTPJ) on facial emotion processing of individuals with high autistic traits using eye-tracking technology. Twenty-nine participants with high autistic traits completed an eyetracking task (including happy, fearful and neutral faces) before and after five consecutive days of stimulation (anodal or sham). Results showed that anodal HD-tDCS significantly increased fixation time and fixation count in the mouth area, but this effect was not found after the sham stimulation. Moreover, this increased effect of mouth recognition with anodal rTPJ HD-tDCS was shown in both happy and fearful faces, but no remarkable difference was found in neutral faces. These findings suggest that right TPJ anodal HD-tDCS can facilitate emotional face processing in individuals with high autistic traits.