T SPEED-ACCURACY OPERATING CXARACTE

An analysis of the relationship between speed and accuracy of performance under a wide variety of task conditions reveals a linear relationship between log odds in favor of a correct response and reaction time. This result is consistent !vith the conceptual logic of the statistical decision model of choice reaction time and suggests the definition of a speed-accuracy operating characteristic analagous to the receiver operating characteristic in signal detection. Emptical research on the relationship between speed and accuracy of performance in a reaction time setting has taken on a new importance in recent years for several rezksons. At the theoretical level, the research on models of choice reaction time (CRT) has found a congenial approach in the statistical decision or random-walk model. (STONE, 1960; FITTS, 1966; EDWARDS, 19165). One of the most robust predictions of this kind of model is the existence of an orderly trade-off between s and accuracy of perforrl-ante. At the empirical level CRT experiments have always been plagued with problems of intercomparison because of the difficulty of maintaining constant error rates or of comparing CRTs when they were variable. Finally, at the applied level, the assessment of performance efficiency implies understanding the relative contribution of speed and accuracy to loverall efficiency. One frequently would like to ask, ‘How much time is an error worth?’ R. G. Swensso? of our laboratory is currently preparing a thorough review of the discrimination and CRT literature in which inferences concerning spe& vs. accuracy are definable. In this paper I would like to present some previously unanalyzed data on the topic that was colleeted by Professor Fitts shortly before his untimely death in 1965 and to relate them to data from other experiments in which speed versus accuracy was an independent variable. FinaJy, I will include a preview of solme data collected by Mr. Swensson as a part of his doctoral thesis he direction of Dr. Ward Edwards that shed further light on the ies of t.he speed-accuracy trade-off.