Why does double dissociation of function, observed through lesion studies, strongly support distinct cognitive modules in language processing, rather than a single integrated system?

💡 Explanation

Double dissociation demonstrates that damage to area A impairs function X but not Y, while damage to area B impairs function Y but not X; therefore, this independent impairment indicates that X and Y rely on distinct neural substrates, rather than a shared, integrated system because an integrated system would predict correlated deficits.

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