Stanford-Binet & WAIS IQ Differences and Their Implications for Adults with Intellectual Disability (aka Mental Retardation).

Department of Behavioral Psychology, Kennedy Krieger Institute, and Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine.
Intelligence (Impact Factor: 3.25). 03/2010; 38(2):242-248. DOI: 10.1016/j.intell.2009.12.005
Source: PubMed


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 aging-related cognitive declines, and diagnosis of ID in forensic cases involving a possible death penalty.

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    • "The implications of the current study when considered with the results of Dawson et al. (2007), Souliè res et al. (2011) study, and studies of similar standardized assessments in clinical samples (Silverman et al., 2010) are that the cognitive differences characteristic of ASD cannot be reduced to or fully revealed by performance on an IQ test despite test form. This is partially due to the limitations inherent in the use of standardized tests to measure intelligence in general. "
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    ABSTRACT: Previous work has suggested that the Raven's Progressive Matrices (RPM) are better suited for capturing the nature of intelligence for individuals with autism spectrum disorder (ASD) than the Wechsler scales. The RPM measures ‘fluid intelligence’, an area for which it has been argued that persons with ASD have a relative strength. Given that measures of intelligence are used for establishing clinical diagnoses, for making educational decisions, and for group-matching in research studies, continued examination of this contention is warranted. In the current study, verbal children with ASD performed moderately better on the RPM than on the Wechsler scales; children without ASD received higher percentile scores on the Wechsler than on the RPM. Adults with and without ASD received higher percentile scores on the Wechsler than the RPM. Results suggest that the RPM and Wechsler scales measure different aspects of cognitive abilities in verbal individuals with ASD. For the verbal children and adults with ASD in the current study, the RPM and Wechsler scales have unique contributions that must be considered in context when establishing a baseline of cognitive function. The results of this investigation highlight the importance of thoughtfully selecting appropriate measures of intelligence consistent with clinical, educational, and research purposes, especially for verbal children and adults with ASD.
    Full-text · Article · Nov 2014 · Research in Autism Spectrum Disorders
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    • "A difference of 10 points or more was found in 85% of the individuals when comparing tests, and 24% had a 20-point difference or more. In contrast, they reported a strong correlation between the two tests (r = 0.82) indicating that, despite the large differences between the two instruments, they measured the same basic construct (Silverman et al. 2010). Research investigating stability of IQ scores within and between instruments in intellectual disability is scarce and even more so in forensic psychiatric populations. "
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    ABSTRACT: Background A stable assessment of cognition is of paramount importance for forensic psychiatric patients (FPP). The purpose of this study was to compare repeated measures of IQ scores in FPPs with and without intellectual disability (ID). Methods Repeated measurements of IQ scores in FPPs (n=176) were collected. Differences between tests were computed, and each IQ score was categorised. Additionally, t-tests and regression analyses were performed. Results Differences of 10 points or more were found in 66% of the cases comparing WAIS-III with RAVEN scores. Fisher’s exact test revealed differences between two WAIS-III scores and the WAIS categories. The WAIS-III did not predict other IQs (WAIS or RAVEN) in participants with ID. Discussion This study showed that stability or interchangeability of scores is lacking, especially in individuals with ID. Caution in interpreting IQ scores is therefore recommended and. Furthermore, the use of the unitary concept of IQ should be discouraged.
    Full-text · Article · Aug 2014 · Journal of Applied Research in Intellectual Disabilities
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    • "The specific IQ tests and dates of administration were also recorded. We generated a " consensus Full Scale/Composite IQ " for each participant using either the results actually obtained or, in cases where data were only available from the Wechsler Adult Intelligence Scale [37], an estimated " Stanford-Binet-equivalent " was calculated to address the compelling evidence that the various editions of the Wechsler Adult Intelligence Scale generate substantially higher IQs for this population compared to other assessments [38]. Down syndrome was confirmed cytogenetically for 368 (82.9%) individuals; 328 (89.1%) had full trisomy 21, 25 (6.8%) had trisomy 21 mosaicism, and 15 (4.1%) had an autosomal translocation. "
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    ABSTRACT: A myriad of ophthalmic disorders is associated with the phenotype of Down syndrome including strabismus, cataracts, and refractive errors potentially resulting in significant visual impairment. Ophthalmic sequelae have been extensively studied in children and adolescents with Down syndrome but less often in older adults. In-depth review of medical records of older adults with Down syndrome indicated that ophthalmic disorders were common. Cataracts were the most frequent ophthalmic disorder reported, followed by refractive errors, strabismus, and presbyopia. Severity of intellectual disability was unrelated to the presence of ophthalmic disorders. Also, ophthalmic disorders were associated with lower vision-dependent functional and cognitive abilities, although not to the extent that was expected. The high prevalence of ophthalmic disorders highlights the need for periodic evaluations and individualized treatment plans for adults with Down syndrome, in general, but especially when concerns are identified.
    Full-text · Article · Apr 2012 · Current Gerontology and Geriatrics Research
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