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

of thought should be excluded from cognitive science by definition. One example
domain in which synthesis is courted is computational vision.
9.3 Lessons from Natural Computation
To sighted human perceivers, visual perception seems easy: we simply look and see.
Perhaps this is why pioneers of computer vision took seeing for granted. One student
of Marvin Minsky was assigned—as a summer project—the task of programming
vision into a computer (Horgan, 1993). Only when such early projects were
attempted, and had failed, did researchers realize that the visual system was effortlessly
solving astronomically difficult information processing problems.
Visual perception is particularly difficult when one defines its goal as the construction
of internal models of the world (Horn, 1986; Marr, 1976, 1982; Ullman,
1979). Such representations, called distal stimuli, must make explicit the threedimensional
structure of the world. However, the information from which the distal
stimulus is constructed—the proximal stimulus—is not rich enough to uniquely
specify 3-D structure. As discussed in Chapter 8, the poverty of proximal stimuli
underdetermines visual representations of the world. A single proximal stimulus is
consistent with, in principle, an infinitely large number of different world models.
The underdetermination of vision makes computer vision such a challenge to artificial
intelligence researchers because information has to be added to the proximal
stimulus to choose the correct distal stimulus from the many that are possible.
The cognitive revolution in psychology led to one approach for dealing with this
problem: the New Look in perception proposed that seeing is a form of problem
solving (Bruner, 1957, 1992; Gregory, 1970, 1978; Rock, 1983). General knowledge of
the world, as well as beliefs, expectations, and desires, were assumed to contribute
to our visual experience of the world, providing information that was missing from
proximal stimuli.
The New Look also influenced computer simulations of visual perception.
Knowledge was loaded into computer programs to be used to guide the analysis of
visual information. For instance, knowledge of the visual appearance of the components
of particular objects, such as an air compressor, could be used to guide the
segmentation of a raw image of such a device into meaningful parts (Tenenbaum&
Barrow, 1977). That is, the computer program could see an air compressor by exploiting
its pre-existing knowledge of what it looked like. This general approach—using
pre-existing knowledge to guide visual perception—was widespread in the computer
science literature of this era (Barrow & Tenenbaum, 1975). Barrow and Tenenbaum’s
(1975) review of the state of the art at that time concluded that image segmentation
412 Chapter 9