The paper by Gallese and Cuccio provides an integrated theoretical framework explaining how the brain and body relate to social cognition, the human self, and language. The authors review empirical evidence from electrophysiological and neuroimaging studies supporting embodied simulation (ES) theory (Gallese & Cuccio this collection, p. 8). According to ES, the brain covertly simulates the bodily actions, perceptions, and emotions observed in other individuals by using parts of our neural architecture involved in acting, sensing, and feeling emotions. Thereby, we infer the goals, intentions, and states of mind of others in a pre-reflective and non-conceptual fashion. But the authors take this a step further and propose that ES is the key mechanism underlying, and hence unifying, both social cognition, the human self, and language. Throughout the paper, the authors emphasize the tight functional coupling between the body and the brain, which when taken into account bears the potential to significantly advance the scientific study of the hard problem of consciousness (Chalmers 1996).
This commentary on Gallese and Cuccio aims to find the right description of the brain mechanisms underlying pre-reflective aspects of both the bodily self and social cognition. Specifically, I will focus on Gallese and Cuccio’s central claim that ES, based on motor resonance and neural processing in the motor system, is the primary brain mechanism underlying pre-reflective representations of the bodily self and social cognition (Gallese & Cuccio this collection, pp. 8–14). I ask the following questions: Could there be an alternative theory or empirical evidence countering the claim of a primacy of motor resonance underlying social cognition and the bodily self? Which brain mechanisms in addition to motor resonance might contribute to pre-reflective aspects of social cognition and the bodily self? I will defend the following three theses:
(1) Social cognition and the bodily self depend on multisensory spatial coding, which is distinct from motor resonance. Thus, motor resonance may be a necessary but insufficiently “primary” brain mechanism of social cognition and the bodily self (cf. section 1, 2).
(2) The brain networks underlying social cognition and the bodily self largely overlap. Specific functional associations exist (a) between motor resonance and body ownership/agency and (b) between multisensory spatial coding and self-location/the first-person perspective (cf. section 2).
(3) The vestibular system, i.e., the sensory system encoding head motion and gravity, might provide unique information used for multisensory spatial coding that relates the bodily self to other individuals and the external world. This is further suggested by the large overlap existing between the human vestibular cortex and the brain networks underlying the bodily self and social cognition (cf. section 3).
My commentary is structured in three sections. In the first section I shall compare ES to an alternative theory of social cognition that assigns priority to spatial coding of attention, rather than to motor resonance. I shall show that both theories bear the potential that their proposed brain mechanisms cooperatively work together in order to support social cognition. The second section addresses the bodily self. I shall review data from neurological patients and full-body illusion experiments, which highlight the importance of two spatial aspects of the bodily self not mentioned by Gallese and Cuccio, i.e., self-location and the first-person perspective. These spatial aspects of the bodily self depend primarily on multisensory integration and on cortical processing outside regions involved in ES. Furthermore, comparisons between the brain networks encoding the bodily self and social cognition show large overlaps, suggesting shared functional mechanisms. In the third section I propose that because multisensory spatial processing appears to be critical for the bodily self and social cognition, important contributions may come from the vestibular system (Lenggenhager & Lopez this collection). I shall show that the vestibular cortical network largely overlaps with the brain networks underlying the bodily self and social cognition. I shall discuss potential contributions of vestibular cortical processing to these target phenomena and suggest directions for future research.