On the methods of cognitive neuropsychology

Contemporary cognitive neuropsychology attempts to infer unobserved features of normal human cognition, or ?cognitive architecture?, from experiments with normals and with brain-damaged subjects in whom certain normal cognitive capacities are altered, diminished, or absent. Fundamental methodological issues about the enterprise of cognitive neuropsychology concern the characterization of methods by which features of normal cognitive architecture can be identified from such data, the assumptions upon which the reliability of such methods are premised, and the limits of such methods?even granting their assumptions?in resolving uncertainties about that architecture. With some idealization, the question of the capacities of various experimental designs in cognitive neuropsychology to uncover cognitive architecture can be reduced to comparatively simple questions about the prior assumptions investigators are willing to make. This paper presents some of simplest of those reductions. 1Research for this paper was made possible by a fellowship from the John Simon Guggenheim Memorial Foundation and by grant number SBE-9212264 from the National Science Foundation. I thank Martha Farah for teaching me what little I know of cognitive neuropsychology, Jeffrey Bub for stimulating me to think about these issues and for commenting on drafts of this paper, and Peter Slezak for additional comments. Alfonso Caramazza and Michael McCloskey provided very helpful comments on a second draft