Heat Sensitivity

• Heat sensitivity
• Locke's experience

Perhaps the most famous discussion in modern Western philosophy of the experience of temperature, and its underlying physiological concomitants, is given by Locke (1690/1959) in discussing secondary qualities in the perception of physical objects.

Science has found that thermal sensitivity is mediated by a number of different neuronal receptors. These receptors are dorsal root ganglion neurons with cell bodies located near the spinal cord.

Among these receptors are those dedicated to sensing temperatures less than a person’s adapted skin temperature (termed "cold" receptors), temperatures greater than a person’s adapted skin temperature (termed "warm" receptors), receptors that serve to sense significant heat in association with pain (a type of nociceptor), and receptors that serve to sense significant cold in association with pain (also a type of nociceptor). The peripheral terminal of all of these neurons is a bare nerve ending. Cold receptors are activated in a range from about 1°C to 20°C below normal skin temperature, approximately 34°C.

Warm receptors are activated in the range of about 32°C to 45°C. Above about 45°C, the discharge of warm receptors decreases, and the nociceptors associated with the sensation of heat and pain respond.

Hence heat sensitivity is related to the initial temperature of our hands and we need a more objective method to measure what is called “heat”.

• Beaker with cold, warm and hot water — HEA-001, HEA-002, HEA-003