Before revision: In this work , we use Martingale theory to derive formulas for the expected decision time, error rates , and first passage times associated with a multistage drift diffusion model, or a Wiener diffusion model with piecewise constant time-varying drift rates and decision boundaries. The model we study is a generalization of that considered in Ratcliff (1980) .
After revision: In this work , we use Martingale theory to derive formulas for the expected decision time, error rates , and first passage times associated with a multistage drift diffusion model, or a Wiener diffusion model with piecewise constant time-varying drift between two time-varying absorbing boundaries. This model was first studied by Ratcliff (1980) .