Towards an Objective Psychophysics of Pain

The limits of most sensory systems can now be routinely determined by objective detection-theory methods. The threshold of pain, however, is often thought to require more traditional methods that rely on a subject providing some estimate or description of what is perceived. The subject makes a measurement that cannot be contested and, in this sense, the methods are subjective. An experimental study of electrocutaneous stimuli showed how it is possible to interpret a traditional identification method and a category method in detection-theory terms. On this interpretation, these traditional methods yield results similar to a rating method of detection theory, a method that measures sensory resolution. However, the traditional methods give rise to additional judgmental variance not involved in standard detection-theory methods. They therefore do not provide a special insight into the experience of pain, and the extra variance they produce serves only to degrade, rather than to enhance, their usefulness.