Perception of temperature on oral and facial skin.

The intensity of sensations of warmth and cold was measured psychophysically at 12 loci on the face and in the mouth in 20 human subjects. Significant differences were found among areas in the relative sensitivity to both cooling and warming, although the range of sensitivities was greater for warming than for cooling. Except for the vermilion lip and the tongue tip, oral regions were significantly less sensitive to warming than were facial regions. No such difference was found for cooling. The most posterior location tested on the hard palate, for example, exhibited a suprathreshold sensitivity to cooling that equaled or surpassed that of most locations on the face. The tongue tip and vermilion lip possessed relatively high sensitivity to both warming and cooling, with the former locus emerging as the most thermally sensitive oral area so far tested.