Why We Feel Wet Things: How Humans Sense Wetness
The feeling of being wet plays a role in many aspects of our daily lives. We can feel humidity, sweat, a damp towel and other stimuli. Yet this feeling of wetness is unusual since our skin does not have receptors that actually sense wetness. Now, scientists have taken a closer look and have found that the feeling may be more of a "perceptual illusion."
When you sit down on a wet seat or walk through a puddle, you have a perception of wetness. Yet scientists believe that wetness perception is intertwined with our ability to sense cold temperature and tactile sensations, such as pressure and temperature.
In order to better understand how we sense "wetness," the researchers exposed 13 healthy male college students to warm, neutral and cold wet stimuli. The scientists then tested sites on the volunteers' forearms and fingertips. The researchers also performed the wet stimulus test with and without a nerve block, which was achieved by using an inflatable compression cuff to attain enough pressure to dampen A-nerve sensitivity.
So what did they find? It turned out that wet perception increased as temperature decreased. This means that we're far more likely to sense cold wet stimuli than warm or neutral wet stimuli. In addition, the researchers found that we're far less sensitive to wetness when the A-nerve activity is blocked.
"Based on a concept of perceptual learning and Bayesian perceptual inference, we developed the first neurophysiological model of cutaneous wetness sensitivity centered on the multisensory integration of cold-sensitive and mechanosensitive skin afferents," write the researchers in a news release. "Our results provide evidence for the existence of a specific information processing model that underpins the neural representation of a typical wet stimulus."
The findings are published in the Journal of Neurophysiology.