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How are we to make sense of these four properties of Gestalt processes? What do they tell us about the computational and representational mechanism in the brain?
The principle of emergence suggests that perception involves multiple tiny forces all acting in parallel to produce an emergent global state, and the most emergent systems are also continuous, or field-like in nature, as in the case of the soap bubble whose surface and the forces acting within it essentially define a spatial continuum.
In other words, the forces acting on the system induce a change in the system configuration, and that change in turn modifies the forces acting on the system. The system configuration and the forces that drive it are therefore changing continuously in time until equilibrium is attained, at which point the system remains in a state of dynamic equilibrium; that is, its static state belies a dynamic balance of forces ready to spring back into motion just as soon as the balance is upset.
The principle of reification suggests that objects and shapes are represented in the brain not by an abstract symbolic code, nor are they encoded by the activation of individual neurons representing particular features in the scene, but rather, objects are represented in the brain by constructing full spatial effigies of them that appear to us for all the world like the objects themselves-or at least so it seems to us only because we have never seen those objects in raw form, but only through our perceptual representations of them.
Multistability in perception is direct evidence for multistability in the brain. The significance for theories of visual processing is that perception cannot be considered as simply a feed-forward processing performed on the visual input to produce a perceptual output, but rather, perception involves some kind of dynamic process whose stable states represent the final percept. The spontaneous reversals of these illusions demonstrate that the perceptual process is active continuously, and exists in a state of dynamic balance until the balance is upset, when the system settles immediately into another stable state.
Invariance poses perhaps the most profound challenge to theories of perceptual representation. Because perception necessarily begins with a local stimulation of the sensory organ, and yet the patterns recognized in that stimulus appear to be largely independent of that local stimulus.
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