PTC AND PROP BEHAVE DIFFERENTLY IN TESTS OF DISCRIMINATION FROM THEIRSOLVENTS

Better discrimination was possible between phenylthiocarbamide (PTC) s olutions and the pure solvent when the solvent was a tasteless low-con centration NaCl solution to which the subject had adapted than when th e solvent was purified water. The reverse was true for 6-n-propylthiou racil (PROP). The differences in discrimination for PROP and PTC in th e different solvents were caused by differences in the intensity and p ersistence of aftertastes, rather than a more intense perception of th e PTC and PROP tastes per se. This has consequences for traditional ap proaches to measuring taste sensitivity, as well as indicating that PT C and PROP are not necessarily equivalent indicators of 'taster' versu s 'non-taster' status.