Category-ratio scaling of sensory magnitude in comparison with other methods

Abstract: Neely, G. (1995). Category-Ratio Scaling of Sensory Magnitude in Comparison with Other Methods. Stockholm: Department of Psychology, Stockholm University .-The Category-Ratio (CR) scales are designed to convey information about the absolute intensity levels experienced with sensory stimuli, as is often done with category scales, as well as about the growth of perceived intensity with increased sensory magnitude, as is done with ratio scaling procedures. The objective of this dissertation is to assess the CR procedure by comparing it with other methods of scaling sensory magnitude. In four studies describing seven experiments, CR scaling is compared with free magnitude estimation (ME), line production, a seven-graded category scale, the Category-Partitioning (CP) scale, and the Visual Analogue Scale (VAS). The studies covered measurements of perceived exertion, pain, loudness, and the darkness and chromaticness of color chips and included evaluations of response bias, test-retest reliability, and prediction fulfillment. The main result was that the CR scaling procedure yielded data that were similar to ME data with respect to exponents from the psychophysical functions, direct comparisons of scale responses, and measures of reliability while also performing equally well in obtaining absolute level determinations as the CP scale. However, comparisons to both category and ratio scaling techniques indicated that the extreme lower portions of the CR scales, where subjects required to provide decimal responses, were avoided. The CR scaling method proved to be resistant to response biases and yielded results that were in agreement with what could be predicted. It is concluded that the CR scaling method achieved its goal of providing both category and ratio information of perceived magnitude and that the method fulfills most experimental and applied needs.