Good point, Jeff. I can't seem to find my human perception book. Maybe it's bad form, but I'll go by the Wiki page
http://en.wikipedia.org/wiki/Thermoreceptor. It states (with poor grammar)..
Quote:
..The adequate stimulus for a warm receptor is warming, which results in an increase in their action potential discharge rate. Cooling results in a decrease in warm receptor discharge rate. For cold receptors their firing rate increases during cooling and decreases during warming. Some cold receptors also respond with a brief action potential discharge to high temperatures, i.e. typically above 45°C, and this is known as a paradoxical response to heat. The mechanism responsible for this behavior has not been determined. ..
..
..Temperatures likely to damage an organism are sensed by sub-categories of nociceptors that may respond to noxious cold, noxious heat or more than one noxious stimulus modality (i.e they are polymodal). The nerve endings of sensory neurons that respond preferentially to cooling are found in moderate density in the skin but also occur in relatively high spatial density in the cornea, tongue, bladder, and facial skin. ..
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So, apparently, specific pain receptors are involved, explaining the likeness to other pain perceptions you described, Ara. Why pinched-nerve pain feels hot over cold, I can't say. [ed: Maybe pain receptors tend to kick in more quickly or frequently for the case of heat.] In the case of the bath experiment you described, Jens, I'd guess this feeling is due to a relatively constant temperature difference (in a very large bath), as the water draws away the heat by Newton cooling, while your skin maintains approximately the same specific heat capacity. This wakes a person up initially, then becomes eventually draining.
[ed: I just reread your post, Jens, and remembered you were talking about a particular temperature of 35 degC. Oops.]
In this case of two different types of low-level response mechanisms, hot and cool, it would seem that sensory response is to be the measured quantity, instead of measuring a certain maintained amount of heat energy in the skin. So, "No-Heat"associates to No-Hot-Response and therefore does not seem as emotionally powerful or representative as "Cool-Response".
I keep trying to imagine that No-Response normally means atomic particles of air and skin moving and colliding at an almost continual rate. But I don't know how easy it is to internalize this idea. It seemed cumbersome, until I started trying to think about things relative to absolute hot [ed: which is possibly equivalent to absolute zero]. "Man's mind, stretched by a new idea, never goes back to its original dimensions" (OWHolmes).