DIFFERENCES IN TASTE PERCEPTION ASSESSED BY MAGNITUDE MATCHING AND BY CATEGORY-RATIO SCALING

Subjects sensitive and insensitive to the bitter substance 6-n-propylthiouracill(PROP) judged the taste intensity of sucrose, caffeine, and citric acid, using two procedures: (i) magnitude matching, where magnitude estimates of the two groups of subjects were brought to a common scale by assuming equivalence in judgments of blackness of grey papers; and (ii) category-ratio (C-R) scaling, where category ratings were taken as equivalent because they were anchored at the top by 'maximal perceived exertion'. which, according to Borg's hypothesis, should be roughly constant over individuals. Experiment 1 classified non-tasters and tasters of PROP by a suprathreshold measure (filter-paper method), and it showed the two scaling methods to be essentially equivalent; non-tasters of PROP were less sensitive than tasters to sucrose, especially at low concentrations, and slightly less sensitive than tasters to low concentrations ot' caffeine. Experiment 2 classified subjects by absolute threshold, and it showed smaller differences between the groups, especially in magnitude matching, where the two groups appeared to differ in their judgments of darkness of greys.