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Abstract:
The Functions of Vision
Standard accounts of vision implicitly assume that the purpose
of the visual system is to construct some sort of internal model
of the world outside-a kind of simulacrum of the real thing,
which can then serve as the perceptual foundation for all
visually derived thought and action. The association of rich and
distinctive conscious experiences with most of our perceptions
gives credence to the idea that they must constitute a vital and
necessary prerequisite for all of our visually based
behavior.
But even though the perceptual representation of objects and
events in the world is an important function of vision, it should
not be forgotten that vision evolved in the first place, not to
provide perception of the world per se, but to provide distal
sensory control of the many different movements that organisms
make. Many of the visual control systems for the different motor
outputs evolved as relatively independent input-output modules.
Thus, the different patterns of behavior exhibited by
vertebrates, from catching prey to avoiding obstacles, can be
shown to depend on independent pathways from the visual receptors
through to the motor nuclei, each pathway processing a particular
constellation of inputs and each evoking a particular combination
of effector outputs.
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