Multisensory integration, predictive coding and the Bayesian brain: reintegrating the body image and body schema distinction into cognitive science
Watson, Ashleigh Louise
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The classic distinction between the body schema and the body image received renewed interest in cognitive psychology, in part because of the attempts by the leading psychologist Charles Spence and his co-authors to synthesise a mounting body of research into the multisensory nature and functional properties of the neural structures in primate cortex that are sensitive and responsive to cross-modal stimuli generated from the body and objects located close to the body, and the famous rubber hand illusion which purported to illustrate how the perception and understanding of what counts as one’s body, i.e., our body image, can be manipulated to include foreign, body-part-like, objects such as a rubber hand. This approach was intended to settle age old questions about how the body schema – the system sub-personal sensorimotor system that shapes, facilitates and regulates motor control – is implemented in the brain and address historic confusions about how the body schema should be understood as an explanatory concept, as well as the problems surrounding the body schema and image distinction on the grounds of the persistent conflation between the two concepts. However, after offering several proposals as to how the body schema should be used to organise and interpret the empirical data, the distinction fell out of favour with Spence and his colleagues on the grounds of the very problems they intended to resolve. The proposed solution is an alternative theoretical framework that, I shall argue, never materialised. Instead, the various definitions they disseminate, I will claim, simply serve to further perpetuate the same problems and confusions about the body schema. Thus, the current state of the literature on the body image and schema in cognitive psychology is in dire need of a conceptual framework that would help us situate and interpret the important empirical data. I propose that we revisit the philosophical debates that were inspired by the philosopher Shaun Gallagher as part of his project to provide a conceptual analysis of the body schema and image distinction and vindicate its status as an important explanatory device for the explanatory ambitions of embodied cognition. Gallagher’s analysis opens up important questions about how the sub-personal multisensory processes of the body schema not only facilitate moment-by-moment motor behaviours, but how they shape and optimise motor control across developmental timelines, as well the importance of the embodied configuration of an agent and its particular eco-niche for shaping and facilitating its motor behaviours. The second important argument of the thesis is that the response to Gallagher’s analysis has simply served to suppress the line of research that Gallagher inspired because the questions his analysis raises have been overshadowed by more general disputes between Gallagher and his opponents about the shape an analysis of the body schema from the perspective of embodied cognition should take. As such, potentially promising lines of research in relation to the body schema have since dried up. As part of my attempt to make progress on the issues that are laid out at the first and second stages of the thesis, the third stage will involve an exploration into the seminal Bayesian approach to understanding cross-modal cue optimisation as it applies to object perception (Banks & Ernst, 2002) and the recent extension of this paradigm to the multimodal sensorimotor processes that underpin motor behaviour in action-oriented cognitive science (e.g., Friston, 2010). The conclusion of the thesis is that the move from an embodied to an action-oriented analysis of the body schema, and the conceptual distinction of which it is part, provides us with the right kind of theoretical resources to begin to pursue fruitful avenues of research that allow us to begin to address the questions set out by Gallagher’s analysis whilst avoiding (some of) the pitfalls that beset the embodied approach. In the final chapter I use this model of the body schema to illustrate how it can provide the basis for working back up towards a comprehensive theory of the body image and schema distinction, which I then bring to bear on current, as-yet-unaddressed, issues in developmental psychology.