Re: stereovision question

[P3D Josh Rubin <jnr@xxxxxxxxx>]

Jim Crowell writes:  

>   It leads to a very interesting & more general question, however.
>   Given that the signals from the retina may take a 1 or 2
>   hundred milliseconds to reach the brain--& how long it takes
>   depends on the strength of the signal--how can anyone ever catch
>   a baseball?  People are starting to look at this kind of
>   question, but I don't think we're really close to an answer.

What little research I've heard of implies that there is
an hallucination mechanism similar to that reported here
recently (in which the poster was presented with a very
short exposure to a visual scene and, despite the
*sensation* that he could perceive the entire scene,
could not in fact detect an off-axis visual cue.

Similarly, I think that we experience the false perception
that we are perceiving and responding to the baseball's
present location, whereas we are largely responding to a
powerful hallucination of where the ball is, based only 
on information which is hundreds of millisecond old. 
Baseballs are a good example because they are relatively
simple and predictable.

Jim, if you know (and I certainly don't, due to SDD -
Sports Deficit Disorder), how long does the baseball's
full trip take from the time the guy throws it to the
time it crosses the plate?

>   >(can) the visual
>   >cortex adapt like the language centers do, in which the
>   >right hemisphere will assume the tasks of the damaged left
>   >hemisphere if the damage is early?
>   
>   It's very hard to say, because there doesn't seem to be such a
>   large difference in function between the visual areas of the two
>   hemispheres.

Actually, I might have phrased the question better if I 
had asked whether the visual system is plastic enough that
structures and functions normally allocated to stereoscopic
processing could be, or ever are, used for processing purely
monocular information.  It wasn't intended to be limited to
the question whether one hemisphere could pick up the visual
processing duties of the other.

Josh
>   
Joshua N. Rubin (jnr@xxxxxxxxx) 
>   


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