9 PARALLEL VERSIONS OF 4 MEMORY TESTS - AN ASSESSMENT OF FORM EQUIVALENCE AND THE EFFECTS OF PRACTICE ON PERFORMANCE

Four memory tests, each containing nine parallel forms, were developed and assessed for their suitability for use in psychopharmacological research. The tests measured verbal memory, face-name-occupation associate learning, spatial location memory and memory for visual designs. Twenty-seven healthy subjects completed a different form of each test on each of nine testing occasions. Test form administration order was rotated across subjects to permit the independent assessment of practice effects and test form equivalence. Performance on four of the test forms differed significantly from performance on other forms of the same test. Data from the remaining forms contained no significant test form differences and these were assumed to be equivalent. ANOVA indicated practice-related changes in six of the seven measures examined. Four or five successive test sessions were required before performance stabilized. Initial 'dips' in performance observed in the verbal memory tests were attributed to proactive interference, whilst further performance improvements in spatial location performance that occurred in the last three days of the study may have been caused by the development of mnemonic strategies. Thus, patterns of change with practice varied across the four tests. The results underline the importance of documenting practice effects in relation to repeated memory assessment.