THE PSYCHOLOGICAL REVIEW ON THE POSSIBLE PSYCHOPHYSICAL LAWS

This paper is concerned with the century-old effort to determine the functional relations that hold between subjective continua and the physical continua that are presumed to underlie them. The first, and easily the most influential, attempt to specify the pos-sible relations was made by Fechner. It rests upon empirical knowledge of how discrimination varies with inten-sity along the physical continuum and upon the assumption that jnd's are subjectively equal throughout the con-tinuum. When, for example, discrimi-nation is proportional to intensity (Weber's law), Fechner claimed that the equal-jnd assumption leads to a logarithmic relation (Fechner's law). This idea has always been subject to controversy, but recent attacks upon it have been particularly severe. At the theoretical level, Luce and Edward