Background: Our body is at the basis of how we perceive the world but also of how we perceive ourselves, and thus, it is intimately related to the sense of self. Though ample body of research has focused on self-perception and self-recognition processes, the underlying mechanisms are still unclear. On one hand, face-recognition studies suggest that visual recognition of stored visual features and configurations inform self-face recognition. On the other hand, research on body ownership suggests that self-body representation and recognition largely result from the integration of current multisensory information. The interaction between these two views was assessed in a recent study (Tsakiris, 2008) showing that self-face representation can be modulated by concurrent visuo-tactile stimulation. In two follow-up experiments we further investigate the role of current multisensory stimulation on explicit and implicit tasks of self-face recognition and on the participant’s subjective experience.

Methods: Participants were presented with a movie of someone else’s face (an unknown control face) being touched on the face, whilst the participant’s face was similarly touched either in synchrony or asynchrony. Immediately before and after this induction period, participants performed a task to quantify the effects that visuo-tactile stimulation had in the participants’ perception of their own face. In Experiment 1 we obtained an explicit measure of bias in “self� versus “other� judgments for morphed faces, while Experiment 2 used an implicit measure of sensitivity to dissimilarity between a picture depicting a 50% morphed face and another picture with a varying degree of face morphing. In addition, introspective ratings for perceptual experiences during both synchronous and asynchronous visuo-tactile stimulation conditions were collected.

Results: Experiment 1 shows that changes on explicit self-face recognition have an egopetal or inwards direction of change: the “other’s face� becomes more part of “me�, than “my face� becomes part of the “other�. This effect can not be accounted solely by self-familiarity since asynchronous visuo-tactile stimulation did not produce the same bias. This asymmetrical effect was also observed in the implicit task of Experiment 2, where the sensitivity to dissimilarity of pictures with various degrees of face morphing decreased after synchronous visuo-tactile stimulation only. Analysis of introspective evidence reveals significant changes in the perception of self (e.g. “It seemed like I was looking at my own reflection in a mirror rather than at the other’s face�) and other (e.g. “The other’s face began to resemble my own face�) as a result of synchronous visuo-tactile stimulation.

Conclusions: The present results show that participant’s partly incorporated the other person’s face in their own face representation, suggesting that current multisensory stimulation may indeed alter the internal representation of one’s own face, and the perception of other people as being more similar to us.

Reference
Tsakiris, M. (2008). Looking for Myself: Current Multisensory Input Alters Self-Face Recognition. PLoS ONE, 3(12), e4040.

Acknowledgments: The present research was supported by the ESRC First Grant RES-061-25-0233 to MT.