ON THE PROBLEM OF CATEGORY SCALES IN PSYCHOPHYSICS

E isler , H. On the problem of category scales in psychophysics. Scand. J. Psychol ., 1962, 3 , 81–87.—In the first Part of the paper it is shown that, if three assumptions are granted, the category scale must be logarithmically related to the magnitude scale: K =α log φ +β . In the second part of the paper, the relation K =α log ( kφ+ q) +β is derived, starting from the assumptions that the category scale is a pure function of discrimination and that discrimination is appropriately described by the linear generalization of Weber's law for prothetic continua. We can reconcile these two formulas by defining the zero-point of the magnitude scale as the point where variability vanishes.