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2 The Visual World
their world—for if the perceived world were not segmented, and the important
objects highlighted and made to stand out, it would not be intelligible.
There is no one “correct” way of carving up a scene. What is important for
us may be of no interest in the life of a tiger or a fly, so every species has its
own scheme for carving up the world according to its interests. In technical
language, we say that every animal has its species-specific segmentation of reality,
linked to its world-model. We are hard-wired to believe that our scheme for
dividing the world into objects is the real one, because such a belief is necessary
for existence.
Though our segmentation of reality is partly bound to physical facts, much
of it is arbitrary. However, there is one aspect of any segmentation which is
non-negotiable: It must be self-consistent. What this means is that regardless
of how information is received from the environment—whether visually, by
sound or by touch—there can be no conflict: All the items of information
must support one another. Also, when the organism undertakes actions, its
plan of action must be fully aligned with its scheme of segmentation, so no
discrepancy is ever encountered. So long as its segmentation is self-consistent,
the animal cannot ever become aware of a difference between its world-model
and reality.
The property of self-consistency is the key to understanding animal perception. Even if the experienced visual display is not a geometrically precise replica
of the external scene, the totality of what’s experienced by an individual, taken as
a whole, provides the same information. What this means is that the combined
evidence gained from all the senses, including touch, and most importantly
from active manipulation of the environment—all are in alignment with one
another.
The Shapes of Things
We perceive the world as being a certain way, and it is normal for us to assume
it’s because the world really is that way. We see an object as a cube because it’s
a cube. What we see is corroborated by what we feel by touch, and for most
people that is proof enough that we aren’t mistaken in what we see. Nonetheless,
it will be argued here that this commonsense belief is only partially correct.
It is known that color is not an objective fact of the world, but rather, it’s a
reaction of animal visual systems to the light reflected from objects. There is,
of course, a connection between color as it appears to us and the wavelength
of light. For example, when we have the experience of seeing the color red, the
2 The Visual World
their world—for if the perceived world were not segmented, and the important
objects highlighted and made to stand out, it would not be intelligible.
There is no one “correct” way of carving up a scene. What is important for
us may be of no interest in the life of a tiger or a fly, so every species has its
own scheme for carving up the world according to its interests. In technical
language, we say that every animal has its species-specific segmentation of reality,
linked to its world-model. We are hard-wired to believe that our scheme for
dividing the world into objects is the real one, because such a belief is necessary
for existence.
Though our segmentation of reality is partly bound to physical facts, much
of it is arbitrary. However, there is one aspect of any segmentation which is
non-negotiable: It must be self-consistent. What this means is that regardless
of how information is received from the environment—whether visually, by
sound or by touch—there can be no conflict: All the items of information
must support one another. Also, when the organism undertakes actions, its
plan of action must be fully aligned with its scheme of segmentation, so no
discrepancy is ever encountered. So long as its segmentation is self-consistent,
the animal cannot ever become aware of a difference between its world-model
and reality.
The property of self-consistency is the key to understanding animal perception. Even if the experienced visual display is not a geometrically precise replica
of the external scene, the totality of what’s experienced by an individual, taken as
a whole, provides the same information. What this means is that the combined
evidence gained from all the senses, including touch, and most importantly
from active manipulation of the environment—all are in alignment with one
another.
The Shapes of Things
We perceive the world as being a certain way, and it is normal for us to assume
it’s because the world really is that way. We see an object as a cube because it’s
a cube. What we see is corroborated by what we feel by touch, and for most
people that is proof enough that we aren’t mistaken in what we see. Nonetheless,
it will be argued here that this commonsense belief is only partially correct.
It is known that color is not an objective fact of the world, but rather, it’s a
reaction of animal visual systems to the light reflected from objects. There is,
of course, a connection between color as it appears to us and the wavelength
of light. For example, when we have the experience of seeing the color red, the