Foundations Of Cognitive Science

Cognitive Impenetrability Criterion

The cognitive impenetrability criterion (Pylyshyn, 1984) is an experimental paradigm that is used to determine whether some cognitive function is primitive (part of the functional architecture) or not.  It is based upon the assumption that if some function is a primitive, then it is relatively stable because it is “wired into” the brain.  That is, it cannot be easily modified – for instance, by changing the contents of one’s beliefs.

The paradigm proceeds as follows.  First, some experimental measure of the function of interest is performed as a pre-test.  Second, the contents of a subject’s beliefs are changed, where these content changes are rationally related to the function of interest.  Third, the function is again measured (post-test) after the belief changes.  If the function has changed in a way that is related to the belief changes, then it has been penetrated by cognition, and is not part of the functional architecture.  If the behavior of the function during the post-test is the same as the behavior during the pre-test, then it is said to be cognitively impenetrable, supporting the claim that the function is a primitive.

Cognitive impenetrability has played an important role in the study of mental imagery (Pylyshyn, 1979, 1981) and in the study of apparent motion (Wright & Dawson, 1994).


  1. Pylyshyn, Z. W. (1979). The rate of 'mental rotation' of images:  A test of a holistic analogue hypothesis. Memory and Cognition, 7, 19-28.
  2. Pylyshyn, Z. W. (1981). The imagery debate: Analogue media versus tacit knowledge. Psychological Review, 88(1), 16-45.
  3. Pylyshyn, Z. W. (1984). Computation and Cognition. Cambridge, MA: MIT Press.
  4. Wright, R. D., & Dawson, M. R. W. (1994). To what extent do beliefs affect apparent motion? Philosophical Psychology, 7, 471- 491.

(Added January 2010)

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