There is an increasing interest from both theoretical and empirical perspectives in how the central nervous system dynamically represents the body and how integrating bodily signals arguably gives rise to a stable sense of self and self-consciousness (e.g., Blanke & Metzinger 2009; Blanke 2012; Gallagher 2005; Legrand 2007; Metzinger 2007; Seth 2013). Discussion of the “bodily self”—which is thought to be largely pre-reflective and thus independent of higher-level aspects such as language and cognition—has played an important role in various theoretical views (e.g., Alsmith 2012; Blanke 2012; Legrand 2007; Metzinger 2003; Metzinger 2013; Serino et al. 2013). For example in the conceptualisation of minimal phenomenal selfhood (MPS), which constitutes the simplest form of self-consciousness, Blanke & Metzinger (2009) suggested three key features of the MPS: a globalized form of identification with the body as a whole (as opposed to ownership for body parts), self-location—by which one’s self seems to occupy a certain volume in space at a given time—and a first-person perspective that normally originates from this volume of space.[1] In recent years, an increasing number of studies has tried to manipulate and investigate these aspects of the minimal self as well as other aspects of the bodily self empirically. This chapter aims to show that including the oft-neglected vestibular sense of balance (Macpherson 2011) into this research might enable us to enrich and refine such empirical research as well as its theoretical models and thus gain further insights into the nature of the bodily self. We agree with Blanke & Metzinger (2009) that self-identification, self-location, and perspective are fundamental for the sense of a bodily self and argue that exactly these components are most strongly influenced by the vestibular system. Yet, we additionally want to stress that the phenomenological sense of a bodily self is—at least in a normal conscious waking state—much richer and involves various fine-graded and often fluctuating bodily sensations. We will thus also describe how the vestibular system might contribute to these (maybe not minimal) aspects of bodily self (e.g., the feeling of agency).
The aim of this book chapter is thus to combine findings from human and non-human animal vestibular research with the newest insights from neuroscientific investigations of the sensorimotor foundations of the sense of self. We present several new experimentally testable hypotheses out of this convergence, especially regarding the relation between vestibular coding and the sense of self-location. We first describe the newest advances in the field of experimental studies of the bodily self (section 2) and give a short overview of vestibular processing and multisensory integration along the vestibulo-thalamo-cortical pathways (section 3). In section 4, we present several lines of evidence and hypotheses on how the vestibular system contributes to various bodily experiences thought to underpin our sense of bodily self. We conclude this section by suggesting that the vestibular system not only contributes to the sense of self, but may also play a significant role in self-other interactions and social cognition.