ABSTRACT
This chapter aims to demystify category ratings by outlining the history of their development and by describing their patterns of behavior. Special emphasis is placed on common misuses of category scales and how they can best be used to measure human perceptions, impressions, and values. The development of category scaling as a device for measuring psychological or sensory impressions can be tracked through the history of psychophysics to Weber's Law. Fechner saw in Weber's principle, however, that Just noticeable difference (JND) provide a critical psychological measuring unit which could serve as the basis for a true scale of sensory impressions. Thurstone then demonstrated that measuring JNDs to generate such psychological scales, a time-consuming and awkward process, is unnecessary. Ratings of stimulus acceptability represent a special case with respect to contextual effects because, for many characteristics of stimuli, hedonic impressions are nonmonotonically related to physical intensity.
