An electrophysiological study of the effect of induced muscle tension on pain thresholds.

The subjective judgment of pain is a perceptual task in which the outcome of the judgment bears a complex relationship to the measured intensity of the physical stimulus applied. “ln many cases knowledge of what is happening at the periphery is inadequate or unrelated to the prediction of the pain experience,” (Edwards, 1950). Human behaviour in the perceptual task of judging a stimulus to be painful or nonpainful (the threshold defining task) is in part independent of the intensity of the stimulus applied. Yet the stimulus is by no means irrelevant and, under uniform conditions, excellent differentiation between stimuli of different intensities can sometimes be achieved