Nonparametric Measures of Sensory Efficiency for Sustained Monitoring Tasks

Abstract

The validity of d', the signal detection theory measure of sensory efficiency, seems suspect in applications to vigilance and inspection, and it is suggested that the investigator should use an alternative, distribution-free measure instead. Three nonparametric measures of efficiency which seem particularly well suited to vigilance applications are considered. The measures, AG (Green and Swets, 1966), A' (Pollack and Norman, 1964), and E (McCornack, 1961) are defined and illustrated, and an example is provided demonstrating their use and suitability in analyzing data from a sustained monitoring task. Norman's (1964) nonmetric procedure for comparing performance efficiency is also applied to the data and is shown to provide a useful means for distinguishing between measure-dependent and measure-independent inferences about changes in efficiency. The relative merits of the three non-parametric measures are discussed.