A behavioral characterization of the Drift Diffusion Model and its multi-alternative extension for choice under time pressure

In this paper, we provide an axiomatic foundation for the value-based version of the Drift Diffusion Model (DDM) of Ratcliff (1978), a successful model that describes two-alternative speeded decisions between consumer goods. Our axioms present a test for model misspeciÖcation and connect the externally observable properties of choice with an important neurophysiological account of how choice is internally implemented. We then extend our axiomatic analysis to multi-alternative choice under time pressure. In a nutshell, we show that binary DDM comparisons of the alternatives, paired with Markovian exploration of the consideration set, approximately lead to softmaximization.