Journal of the International Neuropsychological Society



The effects of practice on the cognitive test performance of neurologically normal individuals assessed at brief test–retest intervals


ALEXANDER  COLLIE  a1 a2 c1, PAUL  MARUFF  a2 a3, DAVID G.  DARBY  a1 a2 and MICHAEL  McSTEPHEN  a2
a1 Centre for Neuroscience, The University of Melbourne, Parkville, Victoria, Australia
a2 CogState Ltd, Carlton South, Victoria, Australia
a3 School of Psychological Science, La Trobe University, Bundoora, Victoria, Australia

Abstract

Performance on many cognitive and neuropsychological tests may be improved by prior exposure to testing stimuli and procedures. These beneficial practice effects can have a significant impact on test performance when conventional neuropsychological tests are administered at test–retest intervals of weeks, months or years. Many recent investigations have sought to determine changes in cognitive function over periods of minutes or hours (e.g., before and after anesthesia) using computerized tests. However, the effects of practice at such brief test–retest intervals has not been reported. The current study sought to determine the magnitude of practice effects in a group of 113 individuals assessed with an automated cognitive test battery on 4 occasions in 1 day. Practice effects were evident both between and within assessments, and also within individual tests. However, these effects occurred mostly between the 1st and 2nd administration of the test battery, with smaller, nonsignificant improvements observed between the 2nd, 3rd, and 4th administrations. On the basis of these results, methodological and statistical strategies that may aid in the differentiation of practice effects from drug-induced cognitive changes are proposed. (JINS, 2003, 9, 419–428.)

(Received October 24 2001)
(Revised April 15 2002)
(Accepted May 13 2002)


Key Words: Practice effects; Test–retest; Cognition; Serial assessment; CogState.

Correspondence:
c1 Reprint requests to: Alex Collie, Centre for Neuroscience, The University of Melbourne, C/O 51 Leicester Street, Carlton South, Victoria, 3053, Australia. E-mail: acollie@cogstate.com


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