We would like to thank Christian Pfeiffer for his very well-articulated commentary on our paper “The paradigmatic body: Embodied Simulation, Intersubjectivity, the Bodily Self, and Language” (Gallese & Cuccio this collection). His comments and criticisms offered us the opportunity to further reflect on some of the ideas proposed in our piece. The aim of our paper was to discuss the role of the body in the constitution of the earliest and primary sense of self and others and, also, to emphasize the constitutive role of the body in a specifically human modality of intersubjectivity: language. To be more precise, we identified a biological mechanism, embodied simulation (ES), as a primary source of intersubjectivity, the sense of self, and language. The mechanism of ES is widely described in the paper and its role in human cognition is explained by also resorting to the Aristotelian notion of paradeigma.
The commentary offered by Christian Pfeiffer is focused on a partial aspect of our much wider proposal. In fact, the author only discusses the constitutive role motor resonance has for the sense of self and for social cognition. However, motor resonance is just one dimension of the mechanism of ES. As argued in our paper and elsewhere (see Gallese & Sinigaglia 2011a; Gallese 2014) the mechanism of simulation is widespread in the brain and it also characterizes the nervous structures involved in the experience of emotions and sensations. All these dimensions of ES should be taken into account. To identify ES only with motor resonance is a partial view that may give rise to fallacious arguments.
The main criticism Pfeiffer advances in his commentary is that our proposal for the constitutive role of motor resonance is too narrow. ES, in his view equated to motor resonance, cannot be the primary neurobiological mechanism at the basis of both the sense of self and others. According to Pfeiffer, motor resonance needs to be complemented by other more basic and primary mechanisms. Hence, as an alternative to our proposal, he suggests that multisensory spatial processing can play this role, primarily contributing to the earliest foundation of the sense of self and others. To support this claim, he provides theoretical arguments and presents empirical data structured in three different sections. Each of these sections supposedly provides evidence of the role of multisensory spatial processing in the foundation of a bodily sense of self and others.
In the first section Pfeiffer addresses the issue of intersubjectivity and presents the Attention schema theory (AS). In his proposal, our ability to understand others is primarily based on a mechanism more primitive than ES-as-motor-resonance: spatial coding of attention. AS predicts that we understand the current state of awareness of our conspecifics by means of schematic representations of their states of attention (Pfeiffer this collection, p. 4). In other words, according to AS, by using a representation of the spatial relationship between the individual we are observing and the spatial focus of her/his attention we can likely predict his intentions and, as a consequence, his actions. Pfeiffer (this collection, p. 4) also discusses recent empirical findings on the neural structures underlying the AS. It seems that the neural structures for the spatial coding of attention are based in the right temporo-parietal junctio (TPJ) and in the superior temporal sulcus (STS). These neural structures do not overlap with the neural circuits involved in ES.
In the second section Pfeiffer addresses the issue of the bodily foundation of the sense of self. The experience of being a bodily self can be decomposed into four different aspects (Pfeiffer this collection, p. 5): body ownership, self-location, first-person perspective, and agency. According to Pfeiffer, motor resonance can account only for body ownership and agency, directly contributing to these (non-spatial) aspects of the bodily self. However, for the two spatial components of the bodily self we need a different account. In fact, according to Pfeiffer, empirical evidence suggests that these spatial aspects of the bodily self, which imply multisensory spatial representations, are encoded in a brain region, the TPJ, not characterized by motor resonance. Hence, motor resonance, while being still necessary for the bodily foundation of some basic aspects of the self, is not a sufficiently primary mechanism, since different neural structures are also needed for the bodily foundation of the self. In support of this claim, Pfeiffer discusses data from neurological patients with out-of-body experiences and other kinds of altered states.
Finally, in the third section the constitutive role of the vestibular system to the bodily foundation of both the consciousness of self and others is discussed. It is proposed that this system, which encodes gravity and head motion and is associated with multisensory spatial processing, significantly and primarily contributes to our ability to distinguish between motions of our own body and motions of other people’s bodies, in this way contributing to both the foundation of the sense of self and social cognition. Empirical studies are reported to support these claims. In addition, empirical data showing that the vestibular cortical network overlaps with neural structures underlying the bodily foundation of both the sense of self and others, as discussed in the two previous sections, are presented.
In the light of the empirical evidence discussed in his commentary, Christian Pfeiffer concludes that ES-as-motor-resonance is not a sufficiently primary mechanism on which we can base a unified neurobiological theory of the earliest sense of self and others. In the next section we answer these criticisms.