The Right Temporoparietal Junction Is Causally Associated with Embodied Perspective-taking

Abstract

A prominent theory claims that the right temporoparietal junction (rTPJ) is especially associated with embodied processes relevant to perspective-taking. In the present study, we use high-definition transcranial direct current stimulation to provide evidence that the rTPJ is causally associated with the embodied processes underpinning perspective-taking. Eighty-eight young human adults were stratified to receive either rTPJ or dorsomedial PFC anodal high-definition transcranial direct current stimulation in a sham-controlled, double-blind, repeated-measures design. Perspective-tracking (line-of-sight) and perspective-taking (embodied rotation) were assessed using a visuo-spatial perspective-taking task that required understanding what another person could see or how they see it, respectively. Embodied processing was manipulated by positioning the participant in a manner congruent or incongruent with the orientation of an avatar on the screen. As perspective-taking, but not perspective-tracking, is influenced by bodily position, this allows the investigation of the specific causal role for the rTPJ in embodied processing. Crucially, anodal stimulation to the rTPJ increased the effect of bodily position during perspective-taking, whereas no such effects were identified during perspective-tracking, thereby providing evidence for a causal role for the rTPJ in the embodied component of perspective-taking. Stimulation to the dorsomedial PFC had no effect on perspective-tracking or taking. Therefore, the present study provides support for theories postulating that the rTPJ is causally involved in embodied cognitive processing relevant to social functioning.SIGNIFICANCE STATEMENT The ability to understand another's perspective is a fundamental component of social functioning. Adopting another perspective is thought to involve both embodied and nonembodied processes. The present study used high-definition transcranial direct current stimulation (HD-tDCS) and provided causal evidence that the right temporoparietal junction is involved specifically in the embodied component of perspective-taking. Specifically, HD-tDCS to the right temporoparietal junction, but not another hub of the social brain (dorsomedial PFC), increased the effect of body position during perspective-taking, but not tracking. This is the first causal evidence that HD-tDCS can modulate social embodied processing in a site-specific and task-specific manner.

Keywords: dorsomedial PFC; embodiment; high-definition transcranial direct current stimulation; perspective-taking; right temporoparietal junction; social cognition.

Copyright © 2020 the authors.

Figures

Figure 1.

Experimental setup. Top, Two examples of perspective-taking (Level 2 VPT). Here the participant must answer whether the target (illuminated disc) is to the avatar's left (left image) or right (right image). Middle, Two examples of perspective-tracking (Level 1 VPT). Here the participant must answer yes (right) or no (left) as to whether the avatar can see the illuminated disc. Bottom, Body position of the participant, which was either congruent or incongruent with the avatar's location (specifically, with the direction of mental self-rotation on any given trial). The avatar was at a disparity of 60°, 110°, or 160° from the location of the participant. Figure adapted with permission from Kessler and Rutherford (2010).

Figure 2.

Body position had no effect on response time for perspective-tracking (Level 1 VPT). An effect of angle was identified, such that response time was faster when the angle of difference between the participant and the avatar was 160° compared with both 60° and 110°. Stimulation to either the rTPJ or dmPFC had no effect on perspective-tracking.

Figure 3.

During perspective-taking, a congruency effect was evident during sham HD-tDCS, such that response times were slower when the participant's body position was incongruent compared with when the body position was congruent with that of the avatar. Anodal HD-tDCS to the rTPJ increased the effect of body position as indexed by a greater congruency effect.