ABSTRACT
Since the early work of Weber, psychophysical studies have analyzed mean stimuli responses of subjects, with little attention paid to differences among individuals (1). More recently, factors influencing differences in individual responses have been investigated, with particular emphasis on responses to phenylthiocarbamide (PTC) and 6-npropylthiouracil (PROP). This variability was first described by Fox (2) when his colleagues found PTC very bitter, but he was unable to taste it. Recent studies have found a broad continuum of threshold distributions within tasters and “nontasters.” Bartoshuk and associates (3) proposed that three, rather than two, phenotypical groups exist: nontasters (NTs) who have two recessive genes; medium tasters (MTs) who have one recessive and one dominant gene; and supertasters (STs) who have two dominant genes (3).
