Practice effects in repeated neuropsychological assessments

Abstract The magnitude of the practice effects associated with repeated administration of the same neuropsychological assessment instruments was examined. In two separate research protocols, subjects were administered their respective battery of neuropsychological instruments twice within 7 to 10 days prior to the initiation of any experimental manipulations. Factors of interest included the test-retest reliability correlation coefficients, the magnitude of practice effects, and the intercorrelation matrices among the instruments. In general, the test-retest reliabilities of the neuropsychological instruments were consistent with those found in the general psychological assessment literature. The magnitude of practice effects was greatest on the Logical and Figural Memory Subtests of the Wechsler Memory Scale in both protocols. The intercorrelation matrices may be useful in planning sample sizes for future studies since estimates of statistical power will require the consideration of the intercorrelations among groups of dependent variables.