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How Prior Probability Influences Decision Making: A Unifying Probabilistic Model
Yanping Huang · Abram Friesen · Timothy Hanks · Michael N Shadlen · Rajesh PN Rao

Thu Dec 06 02:00 PM -- 12:00 AM (PST) @ Harrah’s Special Events Center 2nd Floor

How does the brain combine prior knowledge with sensory evidence when making decisions under uncertainty? Two competing descriptive models have been proposed based on experimental data. The first posits an additive offset to a decision variable, implying a static effect of the prior. However, this model is inconsistent with recent data from a motion discrimination task involving temporal integration of uncertain sensory evidence. To explain this data, a second model has been proposed which assumes a time-varying influence of the prior. Here we present a normative model of decision making that incorporates prior knowledge in a principled way. We show that the additive offset model and the time-varying prior model emerge naturally when decision making is viewed within the framework of partially observable Markov decision processes (POMDPs). Decision making in the model reduces to (1) computing beliefs given observations and prior information in a Bayesian manner, and (2) selecting actions based on these beliefs to maximize the expected sum of future rewards. We show that the model can explain both data previously explained using the additive offset model as well as more recent data on the time-varying influence of prior knowledge on decision making.

Author Information

Yanping Huang (University of Washington)
Abram Friesen (DeepMind)
Timothy Hanks (Princeton University)
Michael N Shadlen (Columbia University and Howard Hughes Medical Institute)

Michael Shadlen MD, PhD is an Investigator of the Howard Hughes Medical Institute and Professor of Physiology & Biophysics at the University of Washington, where is also an adjunct Professor of Neurology. He performed undergraduate and medical studies at Brown University and obtained a PhD from UC Berkeley in visual neuroscience under the guidance of Ralph D. Freeman. He received postgraduate clinical training in Neurology at Stanford Medical Center. He then returned to basic neuroscience as a fellow in the laboratory of William T. Newsome, where he began to work on the neurobiology of decision-making. Shadlen studies neurons in the association cortex that process information from the visual cortex to give rise to interpretations, decisions, and plans for behavior. His experiments combine electrophysiology and behavioral and computational methods to advance our knowledge of higher brain function.

Rajesh PN Rao (University of Washington)

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