The five senses (touch, taste, smell, hearing, sight) refer to general, external senses. The other senses mentioned on this node are considered non-general senses, such as proprioception.

Temperature, pressure, and pain, are all aspects of touch. Treating these as separate senses is unecessarily complicated and would be like treating different colors as different senses when they are all interpreted by sight, or different tastes as different senses. Physiologists classify the five general senses based on how they relate to the nervous system, not by any subjective system developed by psychologists or Asian philosophers:

  • Taste is sensed by taste buds, and is enhanced by olfactory sensation.
  • Smell is purely olfactory, and travels to the brain through the olfactory nerve.
  • Sight is perceived from the eyes through the optic nerve to the occipital lobe.
  • Touch is perceived through general heat, pain, or pressure receptors, usually in the skin. These are all classified as touch receptors, just as the different color cones in our retinas are all classified as sight receptors.
  • Hearing is perceived by our ear drum and conducted to our inner ear (cochlea).

Interestingly, no one has mentioned any of the unconscious senses our bodies have. There are not part of the big five, but are senses nonetheless:

  • Insulin is released into our bloodstream when our body senses that our blood sugar has risen; glucagon is released when our body senses that it has fallen.
  • Our body initiates repair to internal damage that it has sensed, even though we may never consciously feel it.
  • If we use cocaine habitually, our body senses the elevated presence of dopamine and reduced the number of dopamine receptors on certain neurons in the brain, even if we are never physically aware of this dopamine consciously.
  • Some would say that some aspects of our nervous system or consciousness sense memories or information from other parts, and this influences our actions. Maybe this one is a stretch . . .