Psychophysics is the scientific study of perceptual phenomena that are produced by physical stimuli. For example, under what conditions would someone call an object ``red''? The stimulus corresponds to light entering the eye, and the perceptual phenomenon is the concept of ``red'' forming in the brain. Other examples of perceptual phenomena are ``straight'', ``larger'', ``louder'', ``tickles'', and ``sour''. Figure 2.21 shows a typical scenario in a psychophysical experiment. As one parameter is varied, such as the frequency of a light, there is usually a range of values for which subjects cannot reliably classify the phenomenon. For example, there may be a region where they are not sure whether the light is red. At one extreme, they may consistently classify it as ``red'' and at the other extreme, they consistently classify it as ``not red''. For the region in between, the probability of detection is recorded, which corresponds to the frequency with which it is classified as ``red''. Section 12.4 will discuss how such experiments are designed and conducted.
Steven M LaValle 2020-01-06