Continuous Recording of Sensory Thresholds and Other Psycho-Physical Variables

Abstract

THE following method of recording continuously a sensory threshold or other psycho-physical variable may, it is thought, be capable of a wide variety of applications to psycho-physiological problems. The intensity of a stimulus is made to increase automatically at a constant rate from a point below the threshold value. When the subject perceives the stimulus, he presses a button, and keeps it depressed for so long as the stimulus is perceptible. The depression of the button is made to reverse the stimulus-control mechanism so that the intensity now decreases automatically at the same constant rate as it before increased. When the subject no longer perceives the stimulus he releases the button, the stimulus control is again reversed, and the cycle of events repeats itself. The system is thus a cyclic one with intermittent control exercised by the human operator, and the stimulus control hunts about the threshold value.