Short-term memory, nonattentional task effects and nonspatial extraretinal representations in the visual system are signs of cognitive penetration. All of these have been found physiologically, arguing against the cognitive impenetrability of vision as a whole. Instead, parallel subcircuits in the brain, each subserving a different competency including sensory and cognitive (and in some cases motor) aspects, may have cognitively impenetrable components.

A direct equivalence between neural function and neural structure does not provide a fruitful approach to understanding brain functioning. Arbib et al. describe a new and powerful approach to circumvent this problem, which they call schema theory. However, in examples they fall prey to the tradition of finding such equivalences, not doing schema theory justice.