Friday, October 23, 2009

IQ practice effect implications for Atkins MR death penalty cases

What are the implications of repeated testing with the same IQ test (practice effects) for Atkins MR related death penalty decisions?

I've been asked this question a number of times but have not had time to search the literature.  Today a generous IQDP reader (Saor Stettler; attorney in CA) sent me a link and PDF copy of a recent review article in the Open Access Journal of Forensic Psychology (click here for PDF copy of the web article).  It looks like a decent review of the literature related to a number of common instruments.  I know there is a pletheor a research on IQ practice effects.  This article might be a good starting point, particularly since it is written in the context of Atkins cases. Below is the citation and abstract.

Thanks to Mr. Stettler for sending this info.  I encourage other readers to sent me links, copies of articles, copies of Atkins decisions, etc.  There is much information available and only so much time to locate it.

Ray, C. L. (2009).  Ethical Implications of Practice Effects on Mental Retardation Claims in Capital Cases.  Open Access Journal of Forensic Psychology, Vol (1).
Using the same intelligence test for multiple examinations of a defendant in a capital case can result in practice effects.  Strict numerical IQ cutoffs are used in some states to determine whether or not a person is considered mentally retarded.  The practice effects of several intelligence tests are reviewed.  Findings are presented regarding practice effects for performance versus verbal items on intelligence tests.  The importance of time frames, IQ, frequency of re-evaluation, and age with respect to practice effects are examined.  Recommendations are discussed concerning the use of intelligence tests in capital cases.

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