Synchronous multisensory stimulation blurs self-other boundaries.

In a study that builds on recent cognitive neuroscience research on body perception and social psychology research on social relations, we tested the hypothesis that synchronous multisensory stimulation leads to self-other merging. We brushed the cheek of each study participant as he or she watched a stranger's cheek being brushed in the same way, either in synchrony or in asynchrony. We found that this multisensory procedure had an effect on participants' body perception as well as social perception. Study participants exposed to synchronous stimulation showed more merging of self and the other than participants exposed to asynchronous stimulation. The degree of self-other merging was determined by measuring participants' body sensations and their perception of face resemblance, as well as participants' judgment of the inner state of the other, closeness felt toward the other, and conformity behavior. The results of this study show how multisensory integration can affect social perception and create a sense of self-other similarity.