Abstract

How much about our interaction with – and experience of – our world can be deduced from basic principles? This talk reviews recent attempts to understand the self-organised behaviour of embodied agents, like ourselves, as satisfying basic imperatives for sustained exchanges with the environment. In brief, one simple driving force appears to explain many aspects of perception and action – the minimisation of surprise or prediction error. In the context of perception, this corresponds to Bayes-optimal predictive coding (that suppresses exteroceptive prediction errors) and – in the context of action – reduces to classical motor reflexes (that suppress proprioceptive prediction errors). We will look at some of the phenomena that emerge from this single principle; such as perceptual synthesis and action selection. I will focus on the key role of precision in making predictions under uncertainty. Neurobiologically, precision may be encoded by the postsynaptic gain of neuronal populations reporting prediction error and is a clear target of neuromodulatory pathologies implicated in many psychiatric disorders. I hope to illustrate this using simulations of in hallucinations and failures of affordance, of the sort seen schizophrenia and Parkinson’s disease.