Evaluating the 'Labeled Magnitude Scale' for Measuring Sensations of Taste and Smell

The Labeled Magnitude Scale (LMS) is a semantic scale of perceptualintensity characterized by a quasi-logarithmic spacing of itsverbal labels. The LMS had previously been shown to yield psychophysicalfunctions equivalent to magnitude estimation (ME) when gustatory,thermal and nociceptive stimuli were presented and rated together,and the upper bound of the LMS was defined as the ‘strongestimaginable oral sensation’. The present study comparedthe LMS to ME within the more limited contexts of taste andsmell. In Experiment 1, subjects used both methods to rate eithertaste intensity produced by sucrose and NaCl or odor intensityproduced by acetic acid and phenyl ethyl alcohol, with the upperbound of the LMS defined as either the ‘strongest imaginabletaste’ or the ‘strongest imaginable odor’.The LMS produced psychophysical functions equivalent to thoseproduced by ME. In Experiment 2 a new group of subjects usedboth methods to rate the intensity of three different tastequalities, with the upper bound of the LMS defined as the ‘strongestimaginable [sweetness, saltiness, or bitterness]’. Inall three cases the LMS produced steeper functions than didME. Experiment 3 tested the hypothesis that the LMS yields datacomparable to ME only when the perceptual domain under studyincludes painful sensations. This hypothesis was supported whenthe LMS again produced steeper functions than ME after subjectshad been explicitly instructed to omit painful sensations (e.g.the ‘burn’ of hot peppers) from the concept of ‘strongestimaginable taste’. We conclude that the LMS can be usedto scale sensations of taste and smell when they are broadlydefined, but that it should be modified for use in scaling specifictaste (and probably odor) qualities. The implications of theseresults for theoretical issues related to ME, category-ratioscales and the size of the perceptual range in different sensorymodalities are discussed. Chem. Senses 21: 323–334, 1996.