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

2pPP39. The effects of criterion variability on relative operating characteristics.

William S. Brown

Brookhaven Natl. Lab., Bldg. 130, Upton, NY 11973-5000

David S. Emmerich

State Univ. of New York at Stony Brook, Stony Brook, NY 11974

The form of the relative operating characteristic (ROC) describing auditory detection typically differs from that expected based on the assumption that the observer's responses reflect underlying distributions that are normal and of equal variance [e.g., Green and Swets, Signal Detection Theory and Psychophysics]. Specifically, it is found that binormal ROCs often have slopes less than one, and are not strictly linear [Watson et al., 283--288 (1964)]. It has been suggested that nonlinear binormal ROCs may be the result of extreme criteria being more variable than those more centrally positioned [Emmerich and Binder, J. Acoust. Soc. Am. Suppl. 1 65, S59 (1979)]. The forms of rating ROCs obtained in an experiment designed to reveal the effects of such variability were consistent with the proposition that criteria associated with ``no'' responses are more variable than those associated with ``yes'' responses. Criterion operating characteristics [Wickelgren, J. Math. Psychol. 5, 102--122], which reflect the relative locations and variances of the boundaries of confidence categories, favored the same interpretation. It is concluded that the variability of criteria defining categories of rated confidence is sizable and not necessarily constant across criteria, and that such variability significantly influences the forms of empirical ROCs determined using confidence ratings in auditory signal detection.