Stanford-Binet and Wechsler Adult Intelligence Scale (WAIS) IQs were compared for a group of 74 adults with intellectual disability (ID). In every case, WAIS Full Scale IQ was higher than the Stanford-Binet Composite IQ, with a mean difference of 16.7 points. These differences did not appear to be due to the lower minimum possible score for the Stanford-Binet. Additional comparisons with other measures suggested that the WAIS might systematically underestimate severity of intellectual impairment. Implications of these findings are discussed regarding determination of disability status, estimating prevalence of ID, assessing dementia and agingrelated cognitive declines, and diagnosis of ID in forensic cases involving a possible death penalty.Current definitions of intellectual disability (ID, mental retardation in previous terminology) have evolved from their predecessors to include three key features: (1) significantly subaverage intellectual functioning (IQ of 70 or below, allowing for measurement error), (b) Correspondence to: Wayne Silverman, Kennedy Krieger Institute, 707 North Broadway, Suite 222s, Baltimore, MD 21205. silvermanw@kennedykrieger.org. Charles Miezejeski is now in private practice, Staten Island, New York; Tiina Urv is now at the Intellectual and Developmental Disabilities Branch, Eunice Kennedy Shriver National Institute on Child Health and Human Development, National Institutes of Health, Bethesda, Maryland.Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
NIH Public Access
Author ManuscriptIntelligence. Author manuscript; available in PMC 2011 March 1.
NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript substantial impairments in adaptive functioning, and (c) onset prior to adulthood (e.g., American Association on Mental Retardation, 2002; American Psychiatric Association, 2000). While considerable debate has focused on characterization of adaptive deficits and associated criteria defining "substantial" impairment (e.g., Clausen, 1972; Reshly, Myers & Hartel, 2002; Widaman & Siperstein, in press), there has been a longstanding consensus regarding best practice for the assessment of intellectual impairment. The gold standard has been a broadly focused and individually administered IQ test that provides a comprehensive measure of overall intelligence (often with other scores reflecting more focused domains of cognitive competency). Historically and currently, the two instruments most widely used in the United States have been the Stanford-Binet (e.g., Roid, 2003) While Flynn (1984;1985) noted that populations improve ...