It feels like it's me: interpersonal multisensory stimulation enhances visual remapping of touch from other to self

Abstract

Understanding other people's feelings in social interactions depends on the ability to map onto our body the sensory experiences we observed on other people's bodies. It has been shown that the perception of tactile stimuli on the face is improved when concurrently viewing a face being touched. This Visual Remapping of Touch (VRT) is enhanced the more similar others are perceived to be to the self and is strongest when viewing one's face. Here, we ask whether altering self-other boundaries can in turn change the VRT effect. We used the enfacement illusion, which relies on synchronous interpersonal multisensory stimulation (IMS), to manipulate self-other boundaries. Following synchronous, but not asynchronous, IMS, the self-related enhancement of the VRT extended to the other individual. These findings suggest that shared multisensory experiences represent one key way to overcome the boundaries between self and others, as evidenced by changes in somatosensory processing of tactile stimuli on one's own face when concurrently viewing another person's face being touched.

Figure 1

The experimental design comprised two experimental sessions, each comprising four consecutive blocks: (a) VRT measurement before IMS. Participants received either a unilateral or a bilateral tactile stimulation on their cheeks. Concurrently they were required to watch a video depicting either their own face or someone else’s face being touched, or just approached, unilaterally or bilaterally, by human fingers. Participants were asked to respond to the side of tactile stimulation, regardless of visual stimulation. (b) Interpersonal Multisensory Stimulation. For two minutes, participants were touched by a cotton bud on the cheek every 2 seconds while watching a video showing an unknown face being touched with a cotton bud on a specularly congruent location in synchrony (in one session) or asynchrony (in the other session) with respect to the touch delivered on the participants’ face. (c) VRT measurement after IMS. This session was similar to the one before IMS, but now the “other’s face” was the face seen during the IMS. (d) A further two-minute IMS was delivered showing a different face and changing the synchrony (either synchronous or asynchronous) of the visuo-tactile stimulation used in the previous IMS block. Finally participants were asked to answer ten questions about their experience during IMS, using a Visual Analogue Scale.

Figure 2

Results obtained for the No-Touch condition both before and after either synchronous or asynchronous IMS. Accuracy in detecting bilateral tactile stimulation while viewing videos showing either one’s face or the other’s face being approached but not touched by two human fingers. Error bars show standard error of the means across participants. Neither main effects nor interactions are significant.

Figure 3

Results obtained for the Touch condition both before and after either synchronous or asynchronous IMS. Accuracy in detecting bilateral tactile stimulation while viewing videos showing either one’s face or the other’s face being touched by two human fingers. Error bars show standard error of the means across participants.