Whether it’s the sticky, sweaty feeling of a humid day, or the feeling of stepping in puddle on a cold day, the sensation of wetness is very distinct. On October 1st, the Journal of Neurophysiology released an article that examined how animals detect wetness. Until now, the underlying process was poorly understood. Unlike insects, there is no known direct mechanism for moisture detection in humans. Sensing wetness is very important for humans, as well as other animals, because remaining dry is critical for thermoregulation, among other vital functions.
While many take the ability to feel “wetness” for granted, the exact mechanism by which humans feel moisture remains a mystery.
The researchers hypothesized that: “wetness perception is intertwined with our ability to sense cold temperature and tactile sensations such as pressure and texture” (1). However, they theorized that the ability is learned rather than innate. In other words, humans learn how wet things feel through experiencing things they know are wet and remembering how they felt. They tested 13 college-aged males to see if they could feel moisture under a variety of different circumstances. They found that the subjects’ sensitivity to wetness increased as temperature decreased, and that hairy skin is more sensitive than hairless, skin, even when the actual level of physical wetness was held constant.
Since the feeling of wetness is just a combination of other physical stimuli, it is possible to perceive moisture even when there is not any. Feelings of phantom wetness are a common symptom of a neurological disorder called dysesthesia. Severe pain can also be a symptom of the disorder, and hopefully this research will lead to treatments in the future. Currently, dysesthesia is very difficult to treat, as it can have a wide variety of symptoms and causes. If scientists are able to discover the root causes of human sensations, however, they may be able to discover a more generic treatment (3).
Sources:
1. Why wet feels wet: Understanding the illusion of wetness.. (n.d.). ScienceDaily. Retrieved October 1, 2014, from http://www.sciencedaily.com/
2. Filingeri, D., Fournet, D., Hodder, S., & Havenith, G. (2014). Why wet feels wet? A neurophysiological model of human cutaneous wetness sensitivity. Journal of Neurophysiology, 112(6), 1457-69. Retrieved October 6, 2014, from http://jn.physiology.org/content/early/2014/06/13/jn.00120.2014
3. Dysesthesia – Treatment, Symptoms, Types, Causes.. (n.d.). on HubPages. Retrieved October 6, 2014, from http://medicalcontent.hubpages.com/