"Paul C. Smith" wrote:
> Faith L Florer wrote:
>
> > Does anyone here know why it is that the numbers on a digital
> > clock (and some images on a television screen) appear to jiggle when a
> person is
> > using an electric toothbrush?
Well, what follows is hypothesis. Ordinarily, we have a reflex (vestibulocular
sp?) that moves the eyes to compensate for head voluntary head movements, so we can
move our head but keep the eyes fixated on one spot. You can illustrate this by
fixating on the clock and moving the head from left to right. Receptors in the
semicircular canal detect rapid head movements, and direct compensatory eyeball
movements - i.e. the head moves but the eyes continue to fixate. But I have noticed
that if the head is shaken very quickly, we do see the clock jiggle a little, and I
assume this is because the vestibulocular reflex can't keep up with the rapidly of the
head movements. When we use an electric toothbrush - there are two things happening
(1) the head jiggles very rapidly and (2) we are not moving the head voluntarily. Some
combination of (1) and (2) might account for the failure of the vestibulocular reflex
to work. Point (2) can be a discussion in itself. When we move our eyes voluntarily,
we do not see the world jiggle. But if we mechanically move the eyeball (e.g. poke
with a pencil) we do see the visual world jiggling.
At the very least, the vestibuloocular reflex is fun to explain in intro psych.
>
> I'll bet the new list doesn't tackle hard-hitting questions like this one!
Yeah!
--
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John W. Kulig [EMAIL PROTECTED]
Department of Psychology http://oz.plymouth.edu
Plymouth State College tel: (603) 535-2468
Plymouth NH USA 03264 fax: (603) 535-2412
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"The only rational way of educating is to be an example - if
one can't help it, a warning example." A. Einstein, 1934.
