P3D Re: testing stereo vision

[roberts@xxxxxxxxxxxxxxxxx (John W Roberts)]

>Date: Tue, 16 Dec 1997 23:45:59 -0700
>From: Bob Wier <wier@xxxxxxxxxxxxxxxxx>
>Subject: P3D Re: testing stereo vision

>|>Now what's *really* amazing to me are the people who seem to totally
>|>decouple the eye muscles and let one wander around while "viewing"
>|>with the other.

>I've been trying to recall *who* I've seen who can do this - Marty
>Feldman of course had some kind of condition (anyone know what it was?)
>but I don't know if he had that kind of control. There is a comic
>whose name I am totally blank on right now who can do it quite well 
>(seems like Marty something-mumble). Lemme see if I
>can come up with some names.

There were "eye tricks" in a remake of "Invasion of the Body Snatchers"
(and possibly "UHF?"). 

Can the eyes diverge, or be aimed at different elevations?

If you move your finger forward and back along an imaginary line projecting
(typically straight ahead) from one eye, and track your finger with both
eyes, then to another observer it will appear that one eye is looking
straight ahead, while the other crosses and uncrosses. It should be possible
to learn to do that without the finger present. If you can picture an
imaginary object moving about in space and track it with both eyes, both
eyes can be made to appear to be moving independently, though they never
actually diverge or point at different elevations.

Apparently just about everybody has the ability to actually "roll" their
eyeballs (rotate them about an axis through the pupil) by an easily
perceptible amount. (Useful for viewing stereo pairs mounted with slight
rotational errors.) A method for observing this was posted to P3D quite a
while back. Very creepy!

[Disclaimer: I would not recommend that anybody try any of this. I sure
don't plan to.]

John R


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