Self-other merging induced by Interpersonal Multisensory Stimulation increases interpersonal trust behavior.

Studies show that we can change the representation of the self and self-other boundaries, i.e. induce bodily self-other merging. Indeed, experiencing tactile facial stimulation while seeing similar synchronous stimuli delivered to the face of another individual as in a mirror (IMS procedure), induces the subjective illusory experience of ownership and self-attribution bias of the other’s face (Bufalari et al., 2018). Recently we showed that IMS changes self-representations making self- and other- neural processing similar (Bufalari et al., 2019), and that the extent of this effect depends on participants’ empathic traits and interdependent self-construal (Bufalari et al., In preparation). IMS may also change interpersonal perception by increasing closeness, attraction, and perceived similarity towards that specific person (Paladino et al., 2010 ; Toscano & Schubert, 2015). Here, we show that experiencing IMS with a previously unknown other may increase interpersonal trust with that person (as measured by the amount of invested money in the trust game), through increasing bodily self-other merging, and this effect is moderated by perceived trustee’s facial trustworthiness. IMS was efficient in increasing investment only when the trustee was moderately or highly untrustworthy before IMS was applied. In line with the free-energy theoretical account, we speculated that bodily self-other merging may generalize to social processing of others firstly through an increase in perceived physical similarity between self and other (by changing the self-representation and making it similar to the other) and then in conceptual domain, leading to a generalization of positive self-like associations to the other.