Re: Does the human eye have a sampling rate? What is the sampling mechanism?

James,

        You have asked a very interesting question indeed! The visual
system [eyes & nerve pathways to the brain] itself is a complicated bit of
mechanics, however, how the brain process and interprets the information
that the visual system sends it is even more fascinating and complex.

        But, let's keep it as basic as possible to answer your
question[s]. First, as you may know, there are 2 sets of "receptors" in
the visual system; rodas and cones. The rods in the eye are the lowest
light level detectors. They are used for night vision and are very good at
detecting low levels of light, but poor at color perception [for a
detailed mathmatical description of the light sensitivity go to http://
retina.anatomy.upenn.edu/~lance/modelmath/units_photometric.html].
Once their threshold is reached, the information is transmitted to the
visual perception center of the brain [located at the rear of the brain
almost right behind the ears].

        The cones on the other hand are involved with color vision and
more complex objects/scenes. These cells require higher levels of light to
become active. They perform in the same manner as the cones, however they
transmit different types of information.

Up until the point at which the information from the rods
and cones reaches the brain, the process can be described as purely
biological; the information is an 'electric transmission' down the nerves.
Once it reaches the vision center of the brain [the visual cortex], the
psychological process of perception begins.

        There are many different theories of phsychological processing of
vision. A good place to start is an online book called "The Joy of Visual
Perception" by Peter K.Kaiser located at http://www.yorku.ca/research/vision/eye/. He constantly updates 
the site and he covers everything from the biological to the psychological
processes.

        So, a very basic answer is that once a very low threshold of light
is met, the rods immediately begin transmitting a stream of information to
the visual center [cortex] of the brain. There are many different theories
abouthow this information is "decoded". In the interest of time and space
restrictions, it would be more fruitful to follow the link above for
further information.

        Personally, I have dedicated only 10 years of study to the topic.
My primary area of interest has been 3D and spatial processing. My theory of 
visual perception is a combination of several theories proposed by Anne
Triesman, Fred Previc, and Jeremy Wolfe among others.

Pete "window to the mind" Naegele