Illusion - Is Seeing Really Believing?/Illusion - Is Seeing Really Believing (1998)(Marshall Media)[Mac-PC].iso/pc/illusion/rock_txt.cxt/00447_Text_re24bt.txt

Text File | 1997-02-04 | 2KB | 58 lines

    This general principle is
closely related to the "generic
viewpoint assumption": The
visual system assumes that it
does not have a privileged or
special viewpoint of the scene.
In other words, the possibility
that there is coincidental
arrangement between the
viewing direction and the
internal geometry of the scene
is usually not considered. For
example, if the scene in
Chapter 3 of the interposed
rectangle and "circle" were
perceived veridically, then the
smooth continuation of the
contours of the rectangle with
the notch of the circle would
simply be the result of a
coincidental or accidental
alignment. This alignment
could only occur from a single
viewing direction.

    With the emergence of
shaped, segregated units in
perception, stored
representations of prior visual
experience enter into the
story. Most typically, this step
is merely a continuation of the
sequence of bottom-up
processing, consisting simply
of an enrichment of
perception, in the sense that
the object, if familiar, can be
recognized and identified. In
some instances, however, the
representation from memory
can influence the very shape
and organization achieved. We
have seen several examples of
such top-down processing in
previous chapters, one of
which was the reorganization
of fragmented figures that
occurs prior to, or at the
moment of, their recognition.
Even in these instances,
however, the effect of past
experience depends upon the
bottom-up achievement of some
degree of organized shape
perception. Only then is access
to the appropriate memories
possible.