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Active Sensing as Bayes-Optimal Sequential Decision Making
Proceedings of the 29th Conference on Uncertainty in Artificial Intelligence, PMLR R11:15-24, 2013.
Abstract
Sensory inference under conditions of uncer- tainty is a major problem in both machine learning and computational neuroscience. An important but poorly understood aspect of sensory processing is the role of active sensing. Here, we present a Bayes-optimal inference and control framework for active sensing, C-DAC (Context-Dependent Active Controller). Unlike previously proposed al- gorithms that optimize abstract statistical objectives such as information maximization (Infomax) [Butko and Movellan, 2010] or one-step look-ahead accuracy [Najemnik and Geisler, 2005], our active sensing model di- rectly minimizes a combination of behavioral costs, such as temporal delay, response error, and sensor repositioning cost. We simulate these algorithms on a simple visual search task to illustrate scenarios in which context- sensitivity is particularly beneficial and op- timization with respect to generic statisti- cal objectives particularly inadequate. Mo- tivated by the geometric properties of the C- DAC policy, we present both parametric and non-parametric approximations, which retain context-sensitivity while significantly reduc- ing computational complexity. These ap- proximations enable us to investigate a more complex search problem involving peripheral vision, and we notice that the performance advantage of C-DAC over generic statistical policies is even more evident in this scenario.