A New Psychophysical Method.
NAVAL AIR DEVELOPMENT CENTER WARMINSTER PA CREW SYSTEMS DEPT
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In sensory experiments e.g., vision, audition engineers, and experimental psychologists use psychophysical methods to collect data. A typical problem would be a study of the detection of pips on a PPI radar scope. The Method of Limits ML and the Method of Constant Stimuli MCS are two psychophysical methods commonly used. In this report a description is given of a new method that incorporates the beneficial features of the ML and the MCS. Successive stimuli in a series are presented in random order. The data are treated either as data of a ML experiment or as data of a MCS experiment. The mean threshold is the same as that obtained in the ML or in the MCS. For a given number of judgments, the accuracy of the mean threshold is about the same as the accuracy obtained with the ML. The method eliminates knowledge of the order of the stimuli, and allows evaluation of time-correlated fluctuations in sensitivity. Author