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

thus, perceptions, presentations, volitions, and emotions, in short the whole inner
and outer world, are put together, in combinations of varying evanescence and permanence,
out of a small number of homogeneous elements. Usually, these elements
are called sensations. (Mach, 1959, p. 22)
From this perspective, a key issue facing any theory of seeing or visualizing is determining
where sensation ends and where perception begins.
Unfortunately, the demarcation between sensation and perception is not easily
determined by introspection. Subjective experience can easily lead us to the intentional
fallacy in which a property of the content of a mental representation is mistakenly
attributed to the representation itself (Pylyshyn, 2003c). We see in the next
section that the transparency of visual processing hides from our awareness a controversial
set of processes that must cope with tremendously complex information
processing problems.
8.2 The Poverty of the Stimulus
Some researchers have noted a striking tension between experience and science
(Varela, Thompson, & Rosch, 1991). On the one hand, our everyday experience
provides a compelling and anchoring sense of self-consciousness. On the other
hand, cognitive science assumes a fundamental self-fragmentation, because much
of thought is putatively mediated by mechanisms that are modular, independent,
and completely incapable of becoming part of conscious experience. “Thus cognitivism
challenges our conviction that consciousness and the mind either amount
to the same thing or [that] there is an essential or necessary connection between
them” (p. 49).
The tension between experience and science is abundantly evident in vision
research. It is certainly true that the scientific study of visual perception relies heavily
on the analysis of visual experience (Pylyshyn, 2003c). However, researchers are
convinced that this analysis must be performed with caution and be supplemented
by additional methodologies. This is because visual experience is not complete, in
the sense that it does not provide direct access to or experience of visual processing.
Pylyshyn (2003b) wrote,
what we do [experience] is misleading because it is always the world as it appears
to us that we see, not the real work that is being done by the mind in going from the
proximal stimuli, generally optical patterns on the retina, to the familiar experience
of seeing (or imagining) the world. (Pylyshyn, 2003b, p. xii)
Vision researchers have long been aware that the machinery of vision is not a part
of our visual experience. Helmholtz noted that “it might seem that nothing could be
easier than to be conscious of one’s own sensations; and yet experience shows that
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