8THE LAWS OF CATEGORICAL AND COMPARATIVE JUDGEMENT
High threshold theory, although a manifestly inadequate account of decision processes in perception and memory, has been discussed at length because of the powerful sway it has held over the thinking and methodology of experimental psychologists for the last century (Corso, 1963). Psychologists have attempted to measure absolute and difference thresholds, studies of verbal learning have employed corrections for chance guessing, and learning theories (e.g. Hull, 1943) have embodied threshold concepts. Many data are thrown into doubt if the assumptions of signal detection theory are true, although the results of some experiments based on the methodology of threshold theory may be translated into detection theory measures (Treisman & Watts, 1966).