ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

5pPP1. A dynamic, psychophysical model of adaptation in localization experiments.

Barbara Shinn-Cunningham

Res. Lab. of Electron., MIT, 77 Massachusetts Ave., Cambridge, MA 02139

Previous psychophysical models have described how resolution depends upon the range of physical stimuli employed in a given experiment; however, these models generally assume that subject performance is stable over time. The current work extends the context-coding model of Durlach and Braida [ 372--383 (1969); Braida and Durlach, 483--502 (1970)] to account for changes in subject performance that occur when feedback is used to retrain subjects during the course of an experimental session. In the current model, observed changes in performance are accounted for by assuming a single exponential adaptation process. This process, which describes the adaptive state of the subject, determines the decision criteria and context (effective stimulus range) used in the model at a given point in time. From the dynamic decision criteria and effective range, and knowledge of the underlying sensitivity to localization cues, the model predicts mean response, bias, and resolution. The model predictions are in good agreement with results from a relatively large body of experiments, including experiments in which the number and range of stimuli were varied.