There are four physiological systems involved in the perception of balance:
- The bony labyrinth of the inner ear -- pretty much everyone understands this. When the fluid in the labyrinth moves in ways that don't coincide with other senses, it gives a feeling of vertigo (dizziness).
- Visual cues -- being able to see distances to the floor and other objects. This becomes compromised when vision is lost, even if only one eye is affected.
- Tactile cues -- the pressure on your feet or other parts of your body. Depends on at least two contact points; with only one contact point (i.e., standing on one foot), the tactile response is compromised.
- Hearing -- I find that most people don't realize how important hearing is for our sense of balance and orientation. We use passive echolocation without even realizing it. When external sounds echo off of walls and other things, it gives us spatial definition.
As a fun experiment, next time you're taking a shower, close your eyes and stand on one foot. You will find it very difficult to stand upright. Be prepared to catch yourself.
In order to maintain balance, we have to have at least two of the above four physiological systems in agreement. When you take a shower, the white noise of the water running in an small, enclose space nullifies hearing as an element of balance. Closing your eyes nullifies vision. Then, standing on one foot nullifies a third. With nothing else as a reference, the input from your bony labyrinth means nothing and you start to fall.
I'll bet you could repeat the same experiment in an anechoic chamber.
I’ve noticed this phenomenon, but this is a great explanation. Fascinating stuff.
