Derivation and evaluation of a semantic scale of oral sensation magnitude with apparent ratio properties

Abstract

A Scale of oral sensation was constructed by having subjects rate the perceptual magnitudes of semantic descriptors (e.g. ‘weak’, ‘strong’) within the context of imagined gustatory and somesthetic sensations (e.g. ‘the sweetness of banana’, ‘biting the tongue’), then arranging the descriptors according to their mean perceptual intensities. The resulting scale, which we refer to as the oral labeled magnitude scale (LMS), is characterized by a non-linear spacing among its verbal descriptors that, like Borg's (1982) category-ratio scale, is roughly logarithmic. The LMS was evaluated by comparing it with the method of magnitude estimation in an experiment in which subjects rated the intensity of sensations of sweetness, chemical irritation and cold. The psychophysical functions produced by the two methods were not statistically different, indicating that the oral LMS yielded ratio-level data comparable to that produced by magnitude estimation. A final experiment demonstrated the importance of the spacing among semantic descriptors by showing that both the psychophysical functions and the semantic information about perceptual intensity were altered when the descriptors were equally spaced. Theoretical and practical issues related to the empirical approach to scale construction and the generality and robustness of the oral LMS are discussed.