Taking the thumbs off the multidimensional scales in the debate on semantic memory and Alzheimer's disease: a comment on Storms et al. (2003)

G. Storms, T. Dirikx, J. Saerens, S. Verstraeten, and P. P. De Deyn (2003) bring into focus at least 3 important issues. First, the performance of even simple tasks may be affected by several basic cognitive processes. Second, the statistical variance that these processes contribute to task performance may be different for a group of participants with neuropsychological deficits than for normal control particpants. Third, claims regarding the nature of semantic memory in Alzheimer's disease (AD) reflect indeterminacy about the nature and assessment of semantic memory itself. Critically, their analysis suggests that the T. Shallice and E. K. Warrington (1979) criteria widely used to operationalize the semantic memory deficit in AD be carefully scrutinized and reevaluated.