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Illusion - Is Seeing Really Believing?
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Illusion - Is Seeing Really Believing (1998)(Marshall Media)[Mac-PC].iso
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00400_Text_res21t.txt
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1997-02-04
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8
THE UPRIGHT WORLD
Observers floating in a gravity-
free space will still perceive
the orientation of objects in
relation to themselves.
If the retinal images of the
scenes we view are upside
down, why does the world not
appear to be upside down as
well? If an observer were
floating in space far from
Earth, so that the direction of
gravity or other indicators of
"up" and "down" in relation to
the world were unknown and
irrelevant, the question of the
uprightness of vision from an
inverted retinal image could
still be posed. For if a second
person were floating in space
next to the observer, his or her
image would be inverted on the
observerΓÇÖs retina, yet that
person would not appear
inverted.
"Upright" and "inverted" are
defined egocentrically hereΓÇöΓÇô
that is, in terms of how things
appear to be oriented in
relation to the self. But there is
another meaning of "upright"
in perception. "Upright" can
refer to the orientation of a
thing in relation to the
direction of gravity, to how it is
positioned in the environment,
quite apart from how it is
oriented in relation to
ourselves. No matter what may
be our own body orientation,
whether supine or even
standing on our heads, we can
still ask whether or not an
object is perceived to be
vertical or right side up in the
world. In this sense, an object
such as a tree may be perceived
to be right side up even if we
happen to view it when we
ourselves are upside down, thus
rendering it egocentrically
inverted. Here, "upright" (or
"tilted" or "inverted") is
therefore defined
environmentally. As will be
seen, there are some intriguing
problems to be addressed in
understanding both the
perception of an objectΓÇÖs
environmental orientation and
its egocentric orientation.