Cognitive reserve, cognitive rehabilitation, and extended cognition
Abstract
Neuropsychologists posit the existence of ‘cognitive reserve’ to account for
the difference observed in some individuals between the severity of their brain
pathology and the extent of their cognitive impairment. I wish to question the
widespread assumption that only neural mechanisms can underlie cognitive
reserve. I turn to a successful and widely accepted strategy in cognitive
rehabilitation – compensatory rehabilitation with external aids – to show that
neuropsychologists are already relying on the assumption that cognitive
functioning can be increased without any substantial neural changes. This
demonstrates that neuropsychologists are not justified in assuming that only
brain mechanisms can be responsible for cognitive reserve, and in not
considering the alternative explanation that environmental factors may play a
part. I further argue that the model of cognitive functioning suggested by
compensatory rehabilitation is supported and predicted by the philosophical
model of extended cognition. This has implication not only for the concept of
cognitive reserve, but for neuropsychology in general. The increasing success
of cognitive rehabilitation by means of external aids suggests that the
internalist approach to cognition is misguided.