A personal floor effect strategy to evaluate the validity of performance on memory tests

Four methods of assessing the validity of performance on a word recognition test were compared among 609 criminal defendants engaged in competency-to-stand-trial evaluations. One of the methods, the "normative" floor effect strategy, involves comparing an individual's performance to the average performance of individuals with true memory impairment. In this sample, 16.9% of defendants performed below the normative floor for individuals with true impairment. Another method, the "personal" floor effect strategy, identifies performance as suspect when individuals perform below a level for which they themselves have already demonstrated intact ability. In this sample, the personal floor effect strategy identified fewer instances of suspicious performance (15.6%), but the strategy may be less sensitive to true memory impairment than the normative floor effect. Consequently, the personal floor effect strategy may be more compelling as evidence of poor effort or bad intentions on memory testing. Convergent validity of the personal floor effect strategy is demonstrated over four analyses.