Some important methodological issues in the study of aging and cognition.

Despite extensive geropsychological research into cognitive change with advanced age, there is conflicting evidence regarding the nature of this change and even well developed arguments that no decrement with advanced age exists. A review of the field suggests that researchers have neglected certain important parameters which might greatly affect results Specifically, the following topics are examined: (1) determination as to what constitutes "young" and "old", (2) the source of the subjects in aging research, (3) methods of matching subject groups and (4) considerations of group heterogeneity. It was concluded that these issues are often confounded within research designs, that controlling them would help clarify theoretical issues, and that these parameters, when controlled, are themselves worthy of interest.