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CCN Brown Bag Series

Wednesday, September 12, 2018,

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  • Location: Wilson Hall • 111 21St Ave S • Nashville, TN 37240
  • Room: 115

Philip L. Smith, PhD

Melbourne School of Psychological Sciences

The University of Melbourne

"Modeling Speeded Decision Making as Diffusion in Circles, Spheres, and Hyperspheres"

Evidence-accumulation models of decision making provide a powerful and flexible theoretical framework for representing the cognitive and neural processes involved in translating perception into action. The diffusion decision model, in particular, has provided a unified theory of the response time and accuracy data from a wide variety of experimental tasks. In this talk, I will present work that generalizes the diffusion model to higher dimensions. In the first part of the talk, I will present an application of a 2D version of the model that models continuous-outcome decisions as diffusions on the interior of a circle. The model provides a successful account of data from an eye-movement decision task about the hues of noisy color patches, including the decision biases associated with nameable colors. In the second part of the talk, I will present a 4D generalization of the model that models decisions as diffusions on the interior of a hypersphere. The model provides a successful account of performance in a double-target detection task, in which people identified the presence of one or two target stimuli in brief four-element displays. Together, these applications represent a significant generalization of the diffusion model and highlight its utility as a unifying framework for speeded simple decisions.