Such knowledge has enabled
us to clarify some of  the
problems of the perception of
objects and events, but it does
not explain them. Because
scientists have discovered that
the information the visual
cortex receives reflects the
nature of the retinal image, for
example, we know that size and
shape constancy cannot be
explained on the basis of the
central cortical registration of
the size and shape of the image
in the brain. In other words, if
the retinal image is not a
faithful picture of the outer
object, then neither is the
pattern of projection of that
image to the visual cortex.
Therefore, scientists are still
far from identifying the neural
mechanisms of constancy.

    Nor does this accumulated
knowledge about the workings
of the visual nervous system
explain the other facts about
perception outlined in the
preceding pages: How we
achieve veridicality, how the
same image can yield now one
perception and now another,
how organization of the pattern
of stimulation occurs such that
we perceive distinct and
segregated things, or why a
changing image does not
necessarily give rise to a
changing perception.