Theoretical interpretations of the speed and accuracy of positive and negative responses.

The interpretation of the reaction time difference between positive and negative responses in two-choice matching tasks has been the subject of recent controversy. Proctor and his colleagues hold that the difference represents a difference in processing between same and different judgments, whereas Ratcliff and Hacker argued that the difference can be accounted for in terms of criteria settings. In this article, the way in which several models of choice reaction time and matching can account for this reaction time difference is examined and one particular model, the diffusion model of Ratcliff (1981), is fitted to the data from three published experiments. The results of these fits provide a clear interpretation of the reaction time difference in terms of criteria settings. It is concluded that interpretation of such positive-negative reaction time differences in the absence of a specific model is hazardous at best.