A critical look at two typical research designs is presented, the first study being an investigation of field dependence and reaction time in senior tennis players, and the second being an investigation of the concepts of locus of control and achievement motivation in highly successful male competitive tennis players age 65 and older. A critique of the first study indicates some neglect for determining the reasons for differences in performance. A cognitive functional approach is then presented which is intended to alleviate some of the problems of previous research. This approach emphasizes a careful evaluation of the individual's cognitions prior to, during, and following particular learning and performance situations, and attempts to determine which cognitions are contributing to or interfering with effective learning and maximum performance. References are included. (DS)