More on the speed and accuracy of positive and negative responses.

The account given by the diffusion model (Ratcliff, 1985) of the relation between positive and negative responses has been criticized by Proctor, who argues that the diffusion model provides no theory of criterion setting and that it violates psychophysical principles. In reply, I argue that psychophysical principles are not violated and that a quantitative theory of criterion placement is currently outside the scope of the diffusion model and many other models of memory. I point out that the strength of the diffusion model lies in inability to account for aspects of the data other than just mean reaction time (RT), and in its generality across experimental paradigms.