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

paper (Pylyshyn, 1973), which proposed that the primitive properties of images were
not depictive, but were instead descriptive properties based on a logical or propositional
representation. This position represents the basic claim of the propositional
theory, which stands as a critical alternative to the depictive theory. The imagery
debate continues to the present day; propositional theory’s criticism of the depictive
position has been prolific and influential (Pylyshyn, 1981a, 1981b, 1984, 2003a, 2003b,
2003c, 2007).
The imagery debate has been contentious, has involved a number of different
subtle theoretical arguments about the relationship between theory and data, and has
shown no signs of being clearly resolved. Indeed, some have argued that it is a debate
that is cannot be resolved, because it is impossible to identify data that is appropriate
to differentiate the depictive and propositional theories (Anderson, 1978). In this section,
the overall status of the imagery debate is not of concern. We are instead interested
in a particular type of evidence that has played an important role in the debate:
evidence concerning cognitive penetrability (Pylyshyn, 1980, 1984, 1999).
Recall from the earlier discussion of algorithms and architecture that Newell
(1990) proposed that the rate of change of various parts of a physical symbol system
would differ radically depending upon which component was being examined.
Newell observed that data should change rapidly, stored programs should be more
enduring, and the architecture that interprets stored programs should be even more
stable. This is because the architecture is wired in. It may change slowly (e.g., in
human cognition because of biological development), but it should be the most
stable information processing component. When someone claims that they have
changed their mind, we interpret this as meaning that they have updated their facts,
or that they have used a new approach or strategy to arrive at a conclusion. We don’t
interpret this as a claim that they have altered their basic mental machinery—when
we change our mind, we don’t change our cognitive architecture!
The cognitive penetrability criterion (Pylyshyn, 1980, 1984, 1999) is an experimental
paradigm that takes advantage of the persistent “wired in” nature of the
architecture. If some function is part of the architecture, then it should not be
affected by changes in cognitive content—changing beliefs should not result in a
changing architecture. The architecture is cognitively impenetrable. In contrast, if
some function changes because of a change in content that is semantically related to
the function, then this is evidence that it is not part of the architecture.
If a system is cognitively penetrable then the function it computes is sensitive,
in a semantically coherent way, to the organism’s goals and beliefs, that is, it can
be altered in a way that bears some logical relation to what the person knows.
(Pylyshyn, 1999, p. 343)
The architecture is not cognitively penetrable.
110 Chapter 3