Title: Decisions along a continuum: Modeling evidence accumulation in psychological spaces
Abstract: Historically, models of the decision-making process have focused on the case where a decision-maker must choose between two alternatives. The most successful accounts of binary choice and response time, sequential sampling models, have more recently been extended to account for decisions between multiple alternatives. In this talk, I present a geometric representation of diffusion and accumulator models of multiple-choice decisions, and use this to illustrate the psychological assumptions they make about the available choice alternatives as well as how they can be analyzed as Markov random walks on a lattice. I use this geometric framework as a basis for modeling decisions along a continuum of alternatives by adjusting the models’ assumptions regarding the psychological relationships between choice options. I then apply the framework to modeling behavior in a perceptual task where participants must reproduce the orientation of a noisy stimulus. In doing so, I also examine continuous analogues of common two-alternative accuracy and response time phenomena such as difficulty effects, the speed-accuracy trade-off, and starting point biases in evidence accumulation.
