T3D Re: viewing disparity

[Jim Crowell <crowell@xxxxxxxxxxxxxxx>]

At 6:55 PM -0700 9/23/98, Gabriel Jacob wrote:
>
>Jim Crowell writes:
>>It's called "vergence micropsia". The convergence angle of your eyes
>>has an effect on how big things look (which makes sense; if your
>>eyes are converged, then you must be looking up close & whatever
>>you're looking at must be small).  However, this effect is basically
>>unnoticeable unless your eyes  are converged pretty close in.
>
>It's interesting that they have a word for this but have they
>figured why and how the convergence angle determines the apparent
>image size. I remember reading some speculation on P3D that it might
>be simply the optical paths. Simple experiments have led me to
>speculate that rather it's a psychological effect.
>

You're right, it's definitely psychological.  I'm pretty sure you can get
the effect even with afterimages, where of course there are no optics
involved...

The interesting part is that, although this is the sort of effect you'd
expect if the brain were using convergence as a distance cue, the effect of
convergence on perceived distance is smaller than you'd expect from its
effect on perceived size, if that makes any sense...  :-)

-Jim C.

-------------------------------------
Jim Crowell
Caltech Division of Biology
Mail Code 216-76
1200 E. California Blvd.
Pasadena, CA 91125
jim@xxxxxxxxxxxxxxx
http://vis.caltech.edu/~jim/Home.html


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