Co-norming the WAIS-III and WMS-III: Is there a test-order effect on IQ and memory scores?

Test-order effect on the WAIS-III and WMS-III scores was evaluated using th e WMS-III standardization sample. Participants completed the standardizatio n editions of the WAIS-III and WMS-III in one session, with the tests admin istered in roughly counterbalanced order. Repeated measure MANOVA analyses were conducted to determine if there was an overall test-order effect for s ubtest, index, or IQ scores. No significant test-order effects were found f or either the WAIS-III index or IQ scores or for the WMS-III index scores. At the subtest level, the majority of the WAIS-III and WMS-III subtests did not show a significant test-order effect. The exceptions were Digit Span a nd Digit Symbol-Coding on the WAIS-III and Faces II and Logical Memory II o n the WMS-III. Although statistically significant test-order effects were f ound on these subtests, the effect sizes were small. This study indicates t hat the test-order effect is not a potential threat to the internal validit y of the WAIS-III and WMS-III normative data. The practical implications of the current study are discussed.