Thermal taste, PROP responsiveness, and perception of oral sensations

Differences between 6-n-propylthiouracil (PROP) taster groups have long been the focus of studies on individual variation in perception of oral sensation. Recently, "thermal taste" was described, the phenomenon whereby some individuals perceive "phantom" taste sensations after thermal stimulation of small areas of the tongue. As with PROP taster status (PTS), thermal taster status (TTS) has been proposed as a proxy for general responsiveness to oral stimuli. Here we examined the influence of PTS and TTS, independently, on the perceived intensity of sweet, sour, salty, bitter, astringent, and metallic stimuli, and temperature on heating or cooling the tongue. Interactions between PTS and TTS were also examined, and fungiform papillae (FP) density and salivary flow rate (SFR) were determined. Both PTS and TTS were associated with perceived stimulus intensities. PROP super-tasters (pSTs) rated all oral stimuli as more intense than PROP non-tasters (pNTs). Thermal tasters (TTs) gave higher logged ratings than thermal non-tasters (TnTs) for all oral sensations including temperature, with the exception of metallic flavour (at low concentration) and PROP. Examination of ETA-squared values showed that PTS had a greater effect on perceived intensities than did TTS for most sensations. No PTSTTS interaction was found for any oral stimuli. In contrast with PTS, TTS was not associated with FP density, and neither PTS nor TTS were associated with SFR. We conclude that pSTs and TTs possess greater responsiveness across a range of taste and trigeminal stimuli and concentrations.