Which WAIS Was It?

November 16, 2009

Author: Catherine M. Callery (Kate)| Louise M. Tarantino

Few advocates worth their salt have not argued claims under listing 12.05 for mental retardation.  Successfully combing the record - or other sources - for IQ scores can often result in a victory in what otherwise appeared to be a more than up-hill battle.  Listing 12.05C in particular can provide a basis for disability in those claims that simply could not be explained otherwise.  That listing requires an IQ score between 60 and 70, with a secondary impairment not necessarily disabling in and of itself, but which imposes an additional and significant work-related limitation of function.  In other words, the secondary impairment(s) need only be severe.

The IQ requirement of listing 12.05C can be meet even if only one of a series of IQ scores derived from testing is 70 or below.  According to the introduction to the mental impairments listings at 12.00D.6.c, where more than one test score is derived, the lowest is used in conjunction with listing 12.05.  The listing refers specifically to the Wechsler series, referencing the verbal, performance and full scale scores IQs.

All fine and good when we were dealing with reports from the Wechsler Adult Intelligence Scale III (WAIS-III), which reported verbal, performance, and full scale scores.  But what happens now that we are seeing reports derived from the new WAIS-IV, which does not give a verbal and performance IQ score?  Instead, the WAIS-IV, published in 2008, uses new terminology, including Verbal Comprehension Index (VCI), Perceptual Reasoning Index (PRI), Working Memory Index (WMI) and Processing Speed Index (PSI), as well as a Full Scale IQ (FSIQ).

Not to worry – according to SSA and others, the terms VCI and PRI should be substituted for verbal IQs and performance IQs.  The WAIS technical manual, published by Pearson Assessments, states:

The terms Verbal IQ (VIQ) and Performance IQ (PIQ) have been replaced with the terms Verbal Comprehension Index (VCI) and Perceptual Reasoning Index (PRI) respectively.  The terms VCI and PRI should be substituted for the terms VIQ and PIQ in clinical decision-making and other situations where the VIQ and PIQ were previously used. The VCI is composed of subtests measuring verbal abilities that require reasoning, comprehension, and conceptualization, and the PRI is composed of subtests measuring nonverbal reasoning and perceptual organization.

WAIS-IV Administration and Test Scoring Manual at 5.

SSA has apparently adopted this distinction.  According to a Q&A issued by SSA, adjudicators should use the WAIS-IV as they used the WAIS-III or earlier editions.  SSA opines in the Q&A, “[r]egarding the WAIS-IV Working Memory Index (WMI) and Processing Speed Index (PSI), these continue to be lesser factors than the primary FSIQ, VCI and PRI values, and are not considered or applied as IQ scores.”

SSA also notes in the Q&A that the test manual suggests that for children falling within the age range between the WISC-IV and the WAIS-IV, specifically age 16 years to age 16 years, 11 months, the WISC-IV might be more suitable for those who may have below average functioning.

By the way, the WISC-IV, or fourth edition of the Wechsler Intelligence Scale for Children published in 2003, also reports VCI and PRI scores instead of verbal and performance.  “Users of the WISC-III and previous Wechsler intelligence scales should note the change in terminology for the composite scores . . . The terms Verbal IQ (VIQ) and Performance IQ (PIQ) have been replaced with the terms Verbal Comprehension Index (VCI) and Perceptual Reasoning Index (PRI) respectively.” David Wechsler, WISC-IV Administration and Scoring Manual, The Psychological Corporation, 2003, at p. 4.

Why these updates in IQ test instruments? Among other reasons, intelligence tests must periodically be “renormed” to account for the so-called “Flynn effect.”  Despite anecdotal evidence otherwise, the intelligence of Americans has been steadily rising by as much as three IQ points a year, perhaps based in part on better education and nutrition.  The “practice effect” – or the test takers familiarity with the test itself – may also explain why IQ scores rise over the years.  Consequently, WAIS-IV results may well be more beneficial to your claimants in arguing listing 12.05 than more recent WAIS-III test results, which was developed in 1997.

For more on the history of the WAIS and WISC IQ tests, see the March 2007 edition of the Disability Law News, available at www.empirejustice.org. And for more on the new WAIS-IV, its subtests, and norming, see http://www.pearsonassessments.com/NR/rdonlyres/CD662F2D-5255-492D-B22D-3876A667C3D8/0/WAISIV2_6_08.pdf.

SSA’s Q&A (the origin of which has not yet been traced!) is available as DAP #521.