Mind, Body, World- Foundations of Cognitive Science, 2013a

computation approach appeals to elements of classical, connectionist, and embodied
cognitive science.
Initially, the natural computation approach has strong classical characteristics.
It views visual perception as a prototypical representational phenomenon, endorsing
sense-think-act processing.
The study of vision must therefore include not only the study of how to extract from
images the various aspects of the world that are useful to us, but also an inquiry
into the nature of the internal representations by which we capture this information
and thus make it available as a basis for decisions about our thoughts and
actions. (Marr, 1982, p. 3)
Marr’s theory of early vision proposed a series of different kinds of representations
of visual information, beginning with the raw primal sketch and ending with the
2½-D sketch that represented the three-dimensional locations of all visible points
and surfaces.
However representational it is, though, the natural computation approach is
certainly not limited to the study of what Norman (1980) called the pure cognitive
system. For instance, unlike New Look theories of human perception, natural
computation theories paid serious attention to the structure of the world. Indeed,
natural constraints are not psychological properties, but are instead properties of
the world. They are not identified by performing perceptual experiments, but are
instead discovered by careful mathematical analyses of physical structures and
their optical projections onto images. “The major task of Natural Computation is a
formal analysis and demonstration of how unique and correct interpretations can
be inferred from sensory data by exploiting lawful properties of the natural world”
(Richards, 1988, p. 3). The naïve realism of the natural computation approach forced
it to pay careful attention to the structure of the world.
In this sense, the natural computation approach resembles a cornerstone of
embodied cognitive science, Gibson’s (1966, 1979) ecological theory of perception.
Marr (1982) himself saw parallels between his natural computation approach and
Gibson’s theory, but felt that natural computation addressed some flaws in ecological
theory. Marr’s criticism was that Gibson rejected the need for representation,
because Gibson underestimated the complexity of detecting invariants: “Visual
information processing is actually very complicated, and Gibson was not the only
thinker who was misled by the apparent simplicity of the act of seeing” (p. 30). In
Marr’s view, detecting visual invariants required exploiting natural constraints
to build representations from which invariants could be detected and used. For
instance, detecting the invariants available in a key Gibsonian concept, the optic
flow field, requires applying smoothness constraints to local representations of
detected motion (Hildreth, 1983; Marr, 1982).
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