Three theoretical assumptions associated with thermosensory testing [Abstract]

The goal of the study was to explore three theoretical assumptions associated with thermosensory testing, using the local application of thermal stimuli. The first assumption we addressed was that relationship between thermal sensation and physical contact temperature is linear. We also examined the assumption that local thermal discomfort is more sensitive to cold, than it is to heat. Lastly, we examined the assumption that participants exhibit high levels of confidence in repeated thermal sensation ratings, across a wide range of contact temperatures. In nine female, and eight male volunteers, thermal sensation, thermal discomfort, and the confidence in thermal sensation scores, were measured in response to seventeen physical contact temperature stimuli, ranging from 18 to 42o C, applied to the dorsal forearm. Our findings demonstrated that the first theoretical assumption, that local thermal sensations are linearly related to the stimulus temperature, is true. This indicates that the distance between the thermal sensation anchors is close to equal in terms of physical temperatures changes, across the range tested presented. On the contrary, the second assumption, that participants experience local cold as more uncomfortable than local heat stimuli, was not supported by the present data. Rather participants rated a similar thermal discomfort level to both cold and hot thermal stimuli. Indeed, the last assumption presented was also contraindicated by the present study, in which the average confidence of thermal sensation was less than 100% (87.5%). Interestingly, the similar levels uncertainty was observed across the range of physical contact temperature tested.