P3D Re: Pulfrich effect

["KENNETH LUKER" <KLUKER@xxxxxxxxxxxxxxxxxxxxxxx>]

One can see the Pulfrich effect with TWO eyes, too.  Just let your
eyes become accustomed to the dark (take at least ten minutes in a
dark place) and turn on a star-gazer's helper light.  You can make
one by putting a dark red filter over a common flashlight, or better
still, over a small penlight.  Then look at the end of the flashlight
as you move it, lighted, in circles or back and forth.  The light
will apparently lag in its movement behind what you know (due to your
holding the flashlight as it moves) to be the true movement. I get
the feeling of dragging the lighted circle along by means of a short
piece of cord tethered to the lighted end of the flashlight.  The 
physics and physiology of the Pulfrich effect become immediately 
understandable.

Ken Luker_______________________________________________________________
Kenneth Luker
Marriott Library Systems and Technical Services
KLUKER@xxxxxxxxxxxxxxxx


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