An evaluation of assumptions underlying the single-patient-only position in neuropsychological research: a reply.

This note challenges the position adopted by A. Caramazza and W. Badecker (1989, Brain and Cognition 10, 256-295) that, since the a priori classification of patients can only be theoretically arbitrary, the basic unit of analysis in cognitive neuropsychology must be the individual patient. We argue that even if there is no prior theory to justify patient classification, this does not preclude group studies; syndromes are what the world gives us--they constrain theory, permitting groups to be formed for research purposes. We also reexamine a particular example of group-based research that was extensively criticized by Caramazza and Badecker. We confront each of their criticisms, and, again, demonstrate the validity of group-based research.