The theory that a simple choice among n alternatives occurs as a gradual accumulation of "evidence" over time is now widely accepted and has received support from neurophysiological studies. Mathematical models that represent this theory vary somewhat, but all assume that evidence can be represented as a stochastic process that terminates when the level of evidence exceeds a criterion. A signal-detection theory "front end," parameters of which are determined by stimulus factors, provides variability in the rates of evidence accumulation. We will show how temporal cues provided by the events in an experiment can affect the accumulation process. In particular, we will present data showing how subjects exploit task rhythm to improve their performance. We use a diffusion process as a model of the choice task, and Large and Jones' (1999) attentional entrainment model to modulate the parameters of the diffusion process. Together these two models can explain some of the effects we observe in our data, including the elimination of a speed-accuracy tradeoff. |