The Dynamics of Perceptual Decision Making
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How do humans and other animals make decisions? A large body of work has investigated this question in the perceptual domain where subjects make decisions about simple visual stimuli. A critical question concerns the “dynamics” of these decisions: how do they evolve over time and how do top-down processes influence them? In the first part of the talk, I’ll present evidence for the existence of a hierarchy of top-down control processes. These processes influence the selection, decision, and evaluation of visual stimuli and originate from progressively rostral areas within the human lateral frontal cortex. In the second part of the talk, I’ll describe recent work into the computations underlying perceptual decisions. I’ll argue that, contrary to popular theories such as drift diffusion and probabilistic population codes, perceptual decisions are based neither on point estimates nor on full probability distributions. Instead, they are likely based on hybrid representations that include a point estimate supplanted by strength of evidence for that estimate. Finally, I’ll discuss the implications of this coding scheme for human optimality.