Can temperature cause surprising sensations?
{ Multi-Sensory }
When you use this hands-on exhibit…you’ll touch some red and blue metal coils.
The red coils are as warm as bathwater (about 40°C), the blue coils are as cool as ambient room temperature (about 20°C).
This doesn’t sound terribly dangerous, but when you touch a mixture of warm-cool- warm-cool coils, they generate a strange stinging sensation. While this may feel slightly painful, it’s only a tactile illusion and you will not be injured.
If your nervous system didn’t regulate how hot or cold things can be, you could easily burn your flesh with hot or cold burns (like frostbite).
It’s a fine line between pleasure and pain!
This thermal grill illusion (discovered in 1896) is still a mystery to scientists, but it seems to involve pain receptors in your skin being activated when you feel a mixture of ‘safe’ temperatures.
Your skin is embedded with thermoreceptors that respond to either warm or cool temperatures.
You also have pain or nocioceptors that respond once the temperature goes past certain thresholds (thought to be above 45°C and below 10°C).
So, if you touch a really hot surface (say about 70°C), your pain receptors, rather than your warm thermoreceptors, are activated.
Strangely, the mixed coils in this exhibit are set at ‘safe’ temperatures (about 20°C and 40°C), but when you touch the mixture of warm-cool coils, three types of receptors seem to be activated:
- warm thermoreceptors are activated by the warm bars,
- cool thermoreceptors are activated by the cool bars and
- nociceptors, which create the stinging sensation of pain.
If you pull your hand away as a reflex after touching the mixed coils, it’s probably because your spinal cord processed and responded to the simultaneous warm-cool signals and interpreted it to be painful, before your brain was conscious of what was happening.