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Abstract

When inferring mental states of others, individuals’ judgments are influenced by their own state of mind, which has been referred to as egocentric bias. Especially in situations where one holds a different mental state than another person to be interpreted, self-other differentiation is key for an accurate interpretation on the other person’s mind. It has been suggested that the right supramarginal gyrus (rSMG) is involved in self-other differentiation and overcoming egocentric bias in the affective domain. In a double-blind, randomized study 47 healthy adults received active or sham anodal tDCS (1mA, 20min) or a sham stimulation to the rSMG prior to performing a newly developed emotional egocentricity paradigm (SOFE, Self-Other Facial Emotion Judgment Task). In SOFE, subjects are presented with emotionally ambiguous situations (happy or fearful) in which they have to continuously rate 1) their own emotion and 2) the emotion of another person whose facial expression is either congruent or incongruent to the subject’s emotion. Analyses confirmed the presence of an emotional egocentric bias in incongruent trials. We furthermore found that active tDCS applied to the rSMG increased subjects’ ability to overcome egocentric judgments. This effect was valence dependent with significant effects when inferring affective states of happy faces right after imagining oneself in a fear-evoking situation (p<0.05). Our findings extend previous research showing a causal role of the rSMG for emotional self-other distinction to the inferring of emotional states from pictorial stimuli. They additionally point towards valence-specific patterns of rSMG functionality. In a next step the SOFE task will be applied in autism spectrum disorder to characterize egocentric bias suppression and SMG network integrity in an effort to elucidate social cognitive dysfunction in affected individuals.