Magnitude-matching: the measurement of taste and smell

In the method of magnitude-matching, subjects try to judge intensities of sensations from two or more modalities on a single, common scale. Using responses to one modality as a standard makes it possible to compare subjects' suprathreshold perceptions on the other, test modality. A series of ten experiments revealed the following: (i) magnitude-matching ‘works’: with both loudness of tones and lightness of grays as standards, tasters versus nontasters of 6-n-prophylthiouracil (PROP) (as defined by a threshold criterion) show much greater responce to suprathreshold PROP and slightly greater response to surcose; (ii) though superior to rating-scale judgements of sensory intensity made without reference to a second modality, magnitude-matching is not, however, flawless: the cross-modality matching relation produced by a set of magnitude-matches depends systematically on the contextual sets of stimulus levels presented for judgement; (iii) with taste as the standard, old versus young subjects showed only a 25% decrement in responce to the odor intensity of butanol when both groups recieved the same physical (concentration) levels, but a >50% decrement in responce when both groups recieved about the same perceptual levels; (iv) magnitude-matches are much the same whether subjets make their judgements on a bounded rating-scale or an open-ended magnitude-estimation scale: and (v) loudness, lightness and odor intensity serve about equally in magnitude-matching with taste intensity.