The derivation of subjective scales from just noticeable differences.

The study of cumulated jnd scales began with Fechner; Fechner's law is such a scale. Psychophysicists have been deriving such scales and comparing them with scales derived in other ways, notably by fractionation, ever since, and a lot of controversy has resulted. The controversy is particularly hot at present because Stevens and Galanter (16) and Stevens (14) have assembled a lot of data which indicate that cumulated jnd scales do not agree with magnitude scales derived by other methods for intensity continua such as loudness, brightness, and pain. Unfortunately, Fechner's procedure for cumulating jnds, which has been widely defended but not widely applied since his day, rests on an assumption which is inconsistent with