RE: stereovision question

[P3D William Davis <bd3d@xxxxxxxxxxxxx>]

>From the recent thread:

>>   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?
Wait a second (ouch!), is this really a given?  Does it really take
100 to 200 milliseconds for an image to be registered with the brain?
That seems like an awfully long time to me.  Doesn't that work out
to one or two tenths of a second?  Or should I have been paying
more attention in math class?
>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.
>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?

If the pitcher throws a 90 mile per hour fastball, it travels at
about 130 feet per second.  If the time delay cited above is
accurate, then the ball would be in the catcher's mitt just as he
was seeing it 26 feet away.  He would have to be hallucinating to 
take that job! I think a major league pitcher's mound is 90 feet from 
the plate, so around 0.7 seconds for the trip.  A 75 mph fastball
would make the trip in about 0.8 seconds.  

Best regards,
Bill Davis


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