Figure 4. Extended diffusion model (DM) for heading discrimination task.
(A) A drifting particle diffuses until it hits the lower or upper bound, corresponding to choosing ‘left’ or ‘right’ respectively. The rate of drift (black arrow) is determined by heading direction. The time at which a bound is hit corresponds to the decision time. 10 particle traces are shown for the same drift rate, corresponding to one incorrect and nine correct decisions. (B) Despite time-varying cue sensitivity, optimal temporal integration of evidence in DMs is preserved by weighting the evidence by the momentary measure of its sensitivity. The DM representing the combined condition is formed by an optimal sensitivity-weighted combination of the DMs of the unimodal conditions.