Monday, February 21, 2005

Am I Moving? Easier to Fool the Eyes Than the Ears but Surprising Sensory Processing Solutions

This is an interesting study because it shows that although the eyes and ears are closely linked, anticipation can prepare you for what you see, but it cannot prepare you for how you sense movement. It means that you can prepare for visual movement (maybe why watching the road reduces car sickness) by top-down control from the brain that may reduce your sensitivity to visual movement. But you can't cognitive control what your inner ear balance feels.

This is good news for people with visual vertigo or visual perceptive disorders. It's bad news if abnormal movement signals are coming from the vestibular system like degenerative disorders of the ear, migraine, 'mild or other cerebral palsy', or many other conditions that can present as sensory processing or sensory integration dysfunction. In the latter two conditions, the sensory mismatches may occur because some of the central (brain) connections of the vestibular nerves have been damaged.

Here's one of our favorite movement illusions on the web. We took only a small piece of it though, please enjoy the full impact by checking out the link.

If you're dealing with vestibular problems, though, don't despair. The commercial BrainPort is supposed to become available some time this year. BrainPort uses sensory substitution to correct vertigo, and amazingly other sensory disorders like congenital blindness. Because the senses are all linked together, some bright and practical thinking neuroscientists realized that - the eyes don't see, the ears don't hear, and the inner ear doesn't sense balance - the brain does. So if the appropriate signals can be direct to a working sensory system, it can serve as a reasonable substitute. Amazing stuff.

There are other interesting implications of the sight-sound disconnect - if you're interested also check out the article on Video Game Sickness - this is believed to result from the visual-vestibular systems being 'out-of-sync'.
Expectation and the Vestibular Control of Balance
Rotating Snake Page
Video Game or Simulation Sickness
BrainPort Sensory Substitution - Driving What Works

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