Errror in Dr. James Flynn's (2009) WAIS-IV norming data: Quest blog post by Dr. Dale Watson

This is a guest blog post by Dr. Dale Watson.  The opinions expressed do not necessarily reflect the official position of the ICDP blog or the blogmaster.  However, it is of interest to note that the error Dr. James Flynn (2009) made in reporting the WAIS-IV norming date (here reported by Dr. Dale Watson) is true, and was also in a published review that I received a few days after I received Dr. Watson's guest post.  This second verification source (Kaufman, Dillon, & Kirsch, 2013) will be the subject of my next post.

Dr. Dale Watson's guest post 

In an article entitled, The WAIS-III and WAIS-IV: Daubert motions favor the certainly false over the approximately true, Dr. James Flynn analyzed data from a number of IQ tests, including the WAIS-R, WAIS-III, and WAIS-IV to estimate the rate of the “Flynn Effect” on the Wechsler scales in the U.S. over time.[i] He concluded, as have others, that in order to account for the obsolescence of aging IQ test norms, a “Flynn Effect” adjustment of 0.30 points per year from the date of a tests norming should be applied to the obtained IQ test scores (Flynn, 2009; Fletcher et al., 2010). For example, if the WAIS-III (normed in 1995) was administered to an individual in 2005, the obtained IQ should be downwardly adjusted by 0.30 x 10 or 3.0 points. Thus, an obtained IQ score of 72 would result in a Flynn-adjusted score of 69. Such adjustments have been recommended for use in Atkins evaluations (Flynn, 2009; Gresham & Reschly, 2011; cf Hagen et al., 2010).[ii]

Flynn compared the IQ scores obtained on the WAIS-III and the WAIS-IV in a sample of 240 examinees reported in the Technical and Interpretive Manual for the WAIS-IV (2008).[iii] The Technical Manual reported that the mean IQs differed by 2.9 points with the sample mean for the WAIS-IV being 100 and for the WAIS-III 102.9 (Wechsler, 2008, p. 75). However, because these IQ scores were calculated using different combinations of subtests, Flynn re-calculated the IQ scores utilizing the same combination of 11 subtest scores used on the WAIS-III to calculate the IQs. Flynn (2009) noted, “The list of subtests used to compute Full Scale IQ had not only changed, but had dropped from 11 to 10. But, once again, they gave the comparison group all 11 of the old WAIS-III subtests, and once again that was fortunate because it meant that the true obsolescence of the WAIS-III could be measured. I calculated the total standard score the group got on the same 11 WAIS-III and WAIS-IV subtests. Using the totals and the WAIS-III conversion table, I calculated Full Scale IQs for the two tests” (p. 102). 

In examining Flynn’s Table 2, it appears that these calculations included scores for the Picture Arrangement subtest for both the WAIS-III and WAIS-IV. However, the Picture Arrangement subtest is not included in the WAIS-IV so it is quite unclear how this calculation was performed. Moreover, there is a footnote to this table indicating that the “WAIS-IV estimate is eccentric in carrying over WISC-III subtests (and scoring vs. the WAIS-III tables)…” but the meaning of this statement is also uncertain. In addition, substitution of the Symbol Search subtest for Picture Arrangement appears to yield very similar results.

In any case, the point of this note is not to recalculate Flynn’s estimates but rather to point out what appears to be a discrepancy between WAIS-IV norming date provided by Flynn and that found in the Technical and Interpretive Manual for the WAIS-IV. Flynn indicated that the WAIS-IV was normed in 2006 (Table 1) whereas the Manual reported, “The WAIS-IV normative data was established using a sample collected from March 2007 to April 2008.” [iv] If we use 2007 as the mid-point norming date, the time between the norming of the WAIS-III and WAIS-IV is 12 years and not 11 as provided by Flynn. Using the Flynn 2006 date resulted in a calculated Flynn Effect between the WAIS-III and WAIS-IV of 0.306 points per year (+3.37 / 11 years). Using the norming date provided in the manual resulted in a calculated score of 0.281 points per year (+3.37 / 12 years). It is understood that this discrepancy of just 0.025 points is of little practical significance but it should be noted nonetheless. Moreover, the metaphorical splitting of hairs is not uncommon when discussing the Flynn Effect. Hagan et al. (2010) asserted, “Decades of FE research and testimony… depict the amount of this shift as a moving target. For example, Flynn (1998) once identified the annual shift as 0.25 rather than 0.30, but later testified in Ex Parte Eric Dewayne Cathey (2010) that 0.29 would be appropriate. Schalock et al. (2010) have called for an annual adjustment of 0.33” pp. 1-2.[v] Flynn has acknowledged that the results reported in his report are estimates for the Wechsler scales, writing, “It is quite possible that the rate of gain on Wechsler tests is 0.275 or 0.325 points per year” (Flynn, 2009, p. 104). The recalculation noted here is consistent with this judgment. Further, the weight of the available evidence, including that of a recent meta-analysis, continues to support the Flynn Effect adjustment of 0.3 points per year.[vi]

---

[i] Flynn, J. R. (2009). The WAIS-III and WAIS-IV: Daubert motions favor the certainly false over the approximately true. Applied Neuropsychology, 16(2), 98-104. doi: 10.1080/09084280902864360

[ii] Gresham, F. M., & Reschly, D. J. (2011). Standard of practice and Flynn Effect testimony in death penalty cases. Intellectual and Developmental Disabilities, 49(3), 131-140. doi: 10.1352/1934-9556-49.3.131

[iii] Wechsler, D. (2008). Wechsler Adult Intelligence Scale: Technical and interpretive manual (4^th ed.). San Antonio, TX: Pearson.

[iv] Id., p. 22.

[v] Hagan, L. D., Drogin, E. Y., & Guilmette, T. J. (2010). IQ scores should not be adjusted for the Flynn Effect in capital punishment cases. Journal of Psychoeducational Assessment, 28(5), 474-476. doi: 10.1177/0734282910373343

[vi] Fletcher, J. M., Stuebing, K. K., & Hughes, L. C. (2010). IQ scores should be corrected for the Flynn Effect in high-stakes decisions. Journal of Psychoeducational Assessment, 28(5), 469-473. doi: 10.1177/0734282910373341

Another article implicating dlPFC and P-FIT model of intelligence--Importance to general intelligence

Another study implicating dorsolateral prefrontal cortex (dlPFC) and PFIT model of intelligence with regard to general intelligence (g), working memory and white matter tract-moderated functional brain network connectivity. Supports significant components of the three-level explanatory model articulated in MindHub Pub #2.

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Research Byte: IQ score differences in forensic settings--WAIS-III v WRIT

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Research Byte: Which is better measure of intelligence? WAIS-III or WAIS-IV

A new article comparing the changes from the WAIS-III to the WAIS-IV with implications for Atkins cases by Taub and Benson. Below is the abstract. Dr. Taub can be contacted via this link.

A previous IAP AP101 report dealing with WAIS-III/WAIS-IV structural changes is worth reading when reviewing this current article.

 

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Roberts et al (2005) on Wechslers, WJ III and CHC theory

From the above excellent book. See select comments about the Wechslers, WJ III and CHC theory by Roberts et al. - a very good chapter in an excellent book.



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CHC theory and the Wechsler IQ scales and test development

In 1998 Dr. Dawn Flanagan and I published the Intelligence Test Desk Reference book which was the first thorough treatment of CHC theory (then called Extended Gf-Gc theory). This book is now out-of-print.


We then took the concepts from the ITDR and, together with Dr. Sam Ortiz, presented a cross-battery approach to interpreting the Wechsler batteries.


And again, this book is no longer in print. This also means we no longer receive any $ for sales (conflict of interest disclosure).


The research, theory, and conceptual material in the second book is nearly identical to the first, but it was presented in the context of how to upgrade interpretation and understanding of the Wechsler batteries according to the CHC framework. Since then the same CHC overview material has been tweaked and updated in a series of CHC cross-battery books by Flanagan et al. But, the foundation of CHC theory, and how it can be integrated within a conceptual framework of test development and interpretation, is largely the same in these newer CHC cross-battery books.

Thus, given that these "mother and father" books are no longer in print, I took the liberty of copying the first three chapters of the Wechsler oriented book and am now making them available for my readers (click here). I make this material available to provide psychologists who have not done much reading regarding CHC theory an opportunity to have access to the basic foundation of CHC theory to help them see how it can be applied to the interpretation of an intelligence battery (in this case the Wechslers). By choosing the Wechsler material this also helps understand how the Wechsler batteries are evolving (either implicitly or explicitly--see Keith and Reynolds, 2010) when viewed from the lens of CHC theory.

But, one must recognize that this material is a bit dated. An update of CHC theory was later published in 2005 (click here to access...plus some other chapters), and was again updated this year by Schneider and McGrew (click here).

However, the CHC chapter I provide in this blog post, particularly when placed in the context of the Wechsler batteries, provides a solid foundation for understanding CHC theory and its impact on contemporary intelligence test development and interpretation. My goal is to increase awareness of CHC theory and its relevance to psychological assessment and interpretation. My goal is to spur others to become more current re: this now dominant framework in the field of applied IQ testing.


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Research brief: Gender differences in intelligence on the WAIS-III (Irwing, in press)

There has been no shortage of contemporary research on gender differences in cognitive abilities (click here for prior IQs Corner posts), and g (general intelligence) in particular. Irwing has a new article "in press" that contributes to this literature, both by reinforcing some prior findings...but also being at variance with other. The introduction provides a nice brief overview of some of the reasons (primarily methodological) for difference on the male-female g-difference research.

Double click on images to enlarge.








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Does the WAIS-III measure the same intellectual abilities in MR/ID individuals?

I have had a number of people send me copies of this article (see abstracts and journal info below), especially those who do work related to Dx of MR/ID in Atkins death penalty cases.

The abstract is self-explanatory--the authors conclude that the WAIS-III four-factor structure is not validated in an MR/ID population. I can hear a lawyer now--"so Dr. __________, according to MacLean et al. the WAIS-III doesn't measure the same abilities in individuals with MR/ID...so aren't your results questionable?"

A close read of the article suggests the results should be take with a serious grain of salt. In fact, the discussion is primarily a discussion of the various methodological and statistical reasons why the published 4-factor model may not have fit.

As is often the case when dealing with samples of convenience (the authors own words), especially samples of individuals at the lower end of the ability continuum, the variables often show significant problems with non-normality and skew. This is present in this sample. Given that we are dealing with SEM-based statistics, the problem is actually one of not meeting the assumption of multivariate normality. The variables also showed restricted SD's---restricted range of talent, a condition that dampens correlations in a matrix.

While doing extensive modeling research at the Institute for Community Integration at the University of Minnesota, an institute devoted to individuals with MR/ID/DD, I was constantly faced with data sets with these problems. As a result, I was constantly faced with model fit statistics that were much lower than the standard acceptable rules-of-thumbs for model fit statistics...which reflected the less than statistical and distributional robustness of such sample data. The best way to overcome the resultant low model fits (after trying transformations of the variables to different scales), was to compare the fit of competing models. The best fitting model, when compared to competing models, may still show a relatively poor absolute fit value (when compared to the standard rules of thumb), but by demonstrating that it was the best when compared to alternatives, the case could be made that it was still the best possible model given the constraints of the sample data.

This leads to the MAJOR flaw of this study. Although the authors discuss the sample problems above, they only tested one model...the WAIS-III four-factor model. They then looked at the absolute value of the fit statistics and concluded that the 4-factor model was not a good fit. I see this as a major flaw. Since the standard rules-of-thumb for absolute magnitude of fit stats may no longer hold in samples with statistical and distributional problems, they should have specified competing models (e.g., two-factor; CHC-model, single factor, etc.) and then compared the relative model fit statistics before rendering a conclusion.

Finally, as the authors correctly point out, the current results, even with the flaws above, may simply reflect the well-established finding that the differentiation of cognitive abilities is less for lower functioning individuals, and more for higher functioning. This is Spearman's Law of Diminishing Returns (SLODR) [Click here for an interesting recent discussion of SLODR]

Bottom line for the blogmaster--I judge the authors conclusions to be overstated for the reasons noted above, particularly the failure to compare the 4-factor model to alternative models. It is very possible that the 4-factor model may be the best fitting model given the statistical and distributional constraints of the underlying sample data.


Abstract

Intellectual assessment is central to the process of diagnosing an intellectual disability and the assessment process needs to be valid and reliable. One fundamental aspect of validity is that of measurement invariance, i.e. that the assessment measures the same thing in different populations. There are reasons to believe that measurement invariance of the Wechsler scales may not hold for people with an intellectual disability. Many of the issues which may influence factorial invariance are common to all versions of the scales. The present study, therefore, explored the factorial validity of the WAIS-III as used with people with an intellectual disability. Confirmatory factor analysis was used to assess goodness of fit of the proposed four factor model using 13 and 11 subtests. None of the indices used suggested a good fit for the model, indicating a lack of factorial validity and suggesting a lack of measurement invariance of the assessment with people with an intellectual disability. Several explanations for this and implications for other intellectual assessments were discussed.

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IQ test "practice effects"

A practice effect is a major psychometric issue in many Atkins cases, given that both the state and defense often test the defendant with the same IQ battery (most often a Wechsler), and often within a short test-retest interval. Click here to view all ICDP posts that mention practice effects.

Dr. Alan Kaufman has summarized the majority of the literature on practice effects on the Wechslers. He published an article in The Encyclopedia of Intelligence (1994; Edited by Robert Sternberg) that summarized the research prior to the third editions of the Wechsler scales. That article is available on-line (click here).

The most recent summary of the contemporary Wechsler practice effect research is in Lichtenberger and Kaufman (2009) Essentials of WAIS-IV Assessment (p. 306-309). The tables and text provide much about WAIS-IV and some about WAIS-III. The best source for WAIS-III is Kaufman and Lichtenberger, Assessing Adolescent and Adult Intelligence (either the 2002 second edition or the 2006 third edition), especially Tables 6.5 and 6.6 (2006 edition). Below are a few excerpts from the associated text from the 2006 edition

"Practice effects on Wechsler's scales tend to be profound, particularly on the Performance Scale" (p. 202)

"predictable retest gains in IQs" (p.202)

"On the WAIS-III, tests with largest gains are Picture Completion, Object Assembly, and Picture Arrangement"

"Tests with smallest gains are Matrix Reasoning (most novel Gf test), Vocabulary and Comprehension

Block Design improvement most likely due to speed variance--"on second exposure subjects may be able to respond more quickly, thereby gaining in their scores" (p. 204)

One year interval results in far less pronounced practice effects (p. 208).

"The impact of retesting on test performance, whether using the WAIS-III, WAIS-R, other Wechsler scales, or similar tests, needs to be internalized by researchers and clinicians alike. Researchers should be aware of the routine and expected gains of about 2 1/2 points in V-IQ for all ages between 16 and 89 years. They should also internalize the relatively large gain on P-IQ for ages 16-54 (about 8 to 8 1/2 points), andn the fact that this gain in P-IQ swindles in size to less than 6 points for ages 55-74 and less than 4 points for ages 75-889" (p. 209).

"Increases in Performance IQ will typically be about twice as large as increases in Verbal IQ for individuals ages 16 to 54" (p. 209)

Finally, the latest AAIDD manual provides professional guidance on the practice effect.


"The practice effect refers to gains in IQ scores on test of intelligence that result from a person being retested on the same instrument" (p. 38)

"..established clinical practice is to avoid administering the same intelligence test within the same year to the same individual because it will often lead to an overestimate of the examinee's true intelligence" (p. 38).


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IQ test battery publication timeline: Atkins MR/ID Flynn Effect cheat sheet

As I've become involved in consulting on Atkins MR/ID death penalty cases, a frequent topic raised is that of norm obsolescence (aka, the Flynn Effect). When talking with others I often have trouble spitting out the exact date of publication of the various revisions of tests, as I keep track of more than just the Wechsler batteries (which are the primary IQ tests in Atkins reports). I often wonder if others question my expertise...but most don't realize that there are more IQ batteries out there than just the Wechsler adult battery....and, in particular, a large number of child normed batteries and other batteries spanning childhood and adulthood. Thus, I decided to put together a cheat sheet for myself..one that I could print and have in my files. I put it together in the form of a simple IQ battery publication timeline. Below is an image of the figure. Double click on it to enlarge.

An important point to understand is that when serious discussions start focusing on the Flynn effect in trial's, most often the test publication date is NOT used in the calculation of how obsolete a set of test norms are. Instead, the best estimate of the year the test was normed/standardized is used, which is not included in this figure (you will need to locate this information). For example, the WAIS-R was published in 1981...but the manual states that the norming occurred from May 1976 to May 1980. Thus, in most Flynn effect discussions in court cases, the date of 1978 (middle of the norming period) is typically used. This makes recall of this information difficult for experts who track all the major individually administered IQ batteries.

Hope this helpful...if nothing else...you must admit that it is pretty :)  Click on image to view





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French WAIS III study supports primary Gq interpretation of Arithmetic in adults

Interesting study with French WAIS III that provides additional support for quantitative knowledge (Gq) being the primary source of variance in understanding the Arithmetic subtest, as well as some processing speed (Gs) in adults. Click here for prior post on this topic.


Rozencwajg, P., Schaeffer, O., & Lefebvre, V. (2010). Arithmetic and aging: Impact of quantitative knowledge and processing speed. Learning and Individual Differences, 20(5), 452-458.

Abstract

The main objective of this study was to examine how quantitative knowledge (Gq in the CHC model) and processing speed (Gs in the CHC model) affect scores on the WAIS-III Arithmetic Subtest (Wechsler, 2000) with aging. Two age groups were compared: 30 young adults and 25 elderly adults. For both age groups, Gq was an important predictor of Arithmetic score variance (R² = 48% and R² = 45%, respectively). However, in line with Salthouse, the results showed that processing speed predicted Arithmetic scores only for the older adults, not for the younger ones (additional 9% of the variance for the elderly vs. 1% of the variance for the young adults). These results can clarify the ambiguous evolution of Arithmetic scores with aging: Arithmetic performance with aging seems to follow an intermediate path between Gc and Gf. This suggests that both Gq and Gs have an impact on Arithmetic in aging.

Additional quotes from the article

Today, “the CHC model (Cattell–Horn–Carroll theory of cognitive abilities) used extensively in applied psychometrics and intelligence testing during the past decade is a consensus model” (McGrew, 2005, p. 149). CHC is a hierarchical model (Fig. 1) with three strata: factor g (Stratum III), broad abilities (Stratum II), and narrow abilities (Stratum I). Broad CHC abilities (Stratum II) include Gf (fluid intelligence/reasoning), Gc (crystallized intelligence/knowledge), Gv (visual–spatial abilities), Gsm (short-term memory), Gs (cognitive processing speed), and Gq (quantitative knowledge). [Click on images to enlarge them]




In contemporary assessments of intelligence (Flanagan & Harrison, 2005), the Cattell–Horn–Carroll Theory (CHC model) plays an important role in interpreting the scores underlying the Wechsler Scale Subtests. There is some controversy, however, as to the constructs measured by each subtest. As stated above, authors disagree on how to classify Arithmetic in this model.

The first hypothesis tested here concerns the role of quantitative knowledge (Gq) in Arithmetic Subtest performance. Gq has been defined as the wealth (breadth and depth) of a person's “acquired store of declarative and procedural quantitative knowledge. Gq is largely acquired through the ‘investment’ of other abilities, primarily during formal educational experiences. It is important to recognize that RQ (narrow ability, Stratum I), which is the ability to reason inductively and deductively when solving quantitative problems, is not included under Gq, but rather is included in the Gf domain (broad ability, Stratum II). Gq represents an individual's store of acquired mathematical knowledge, not reasoning with this knowledge” (McGrew, 2005, p. 156).

Yet when we look at the performance curve with age (see Fig. 2), we can see firstly that the mean scores on Digit Span (Gsm) and Matrix Reasoning – which is a typical test of fluid intelligence (Gf) ([Schroeder and Salthouse, 2004] and [Verhaeghen, 2003]); – start to decline gradually at the age of 25, whereas the mean score on Arithmetic remains stable until age 70. Secondly, the mean score on Vocabulary – which is a typical test of crystallized intelligence (Gc) (Verhaeghen, 2003) – is close to the teenage level (age 16) after the age of 70, whereas performance drops well below that level on Arithmetic. Analyses of age effects on the WAIS-III subtests among American subjects indicate the same phenomena ([Ardila, 2007] and [Ryan et al., 2000]). Finally, Arithmetic performance with aging seems to follow an intermediate path between Gc and Gf (see Fig. 3). This result is similar to that found by Schroeder and Salthouse (2004), see their [Fig. 1] and [Fig. 2] p. 399 and 400): “All the factors were also influenced by knowledge (vocabulary), with the largest knowledge effects on the numeric/fluency factor” (p. 400).



.....the high correlations obtained between the scores on the Arithmetic Subtest and the new quantitative test, both for the young and older adults, support the hypothesis that the Arithmetic Subtest belongs to factor Gq in the CHC model ([Flanagan and Harrison, 2005] and [Flanagan and Kaufman, 2004])


CHC theory intelligence Cattell-Horn-Carroll WAIS III French WAIS III Gq Gsm Gs Gf working memory Aging IQs Corner Wechslers School psychology Neuropsychology Cognitive abilities


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Psychometric PS to Johnston v Florida (2010) denied appeal re: new WAIS-IV scores

This is a follow-up to my brief comments yesterday regarding the Johstone v Fl (2010) denied MR/ID appeal of two days ago.

As mentioned in the decision and my blog comment, the WAIS-III/WAIS-IV tests correlated .94 in a study reported in the WAIS-IV technical manual.  This is a very high correlation...but does NOT mean that the two tests should be expected to provide identical IQ scores.  I discuss these issues in a prior IAP AP101 report.

The tests have different norm dates and thus, the later version (WAIS-IV) would be expected to provide a lower score based on the Flynn effect.  More importantly, as reported in the IAP AP101 report, when one calculates the standard deviation of the difference score (see page 6 of that report) for a correlation of .94, the resulting value is 5.2 (round to 5 for ease of discussion).  This means that, on average, the WAIS-III/WAIS-IV (even if highly correlated at the .94 level) would in the general population be expected to display a range of difference scores from -5 to +5...or a range of 10 IQ points......in 68% of the population.  Please review that prior report for further explanation and discussion.

Technorati Tags: psychology, forensic psychology, forensic psychiatry, neuropsychology, intelligence, school psychology, psychometrics, educational psychology, IQ, IQ tests, IQ scores, intellectual disability, mental retardation, MR, ID, criminal psychology, criminal defense, criminal justice, ABA, American Bar Association, Atkins cases, death penalty, capital punishment, AAIDD, scientific evidence, Flynn effect, validity, norms, practice effects, Johnstone v Florida, WAIS-III, WAIS-IV, CHC intelligence theory, CHC, Cattell-Horn-Carroll, Daubert standard

Research Bytes: 3-24-10: WAIS-III/WISC-IV score differences in spec. ed. population

Gordon, S., Duff, S., Davidson, T., & Whitaker, S. (2010). Comparison of the WAIS-III and WISC-IV in 16-Year-Old Special Education Students. Journal of Applied Research in Intellectual Disabilities, 23(2),
197-200.


Abstract:

Previous research with earlier versions of the WISC and WAIS has demonstrated that when administered to people who have intellectual disabilities, the WAIS produced higher IQ scores than the WISC. The aim of this study was to examine whether these differences still exist. A comparison of the Wechsler Adult Intelligence Scale - Third Edition (WAIS-III) with the Wechsler Intelligence Scale for Children - Fourth Edition (WISC-IV) was conducted with individuals who were 16?years old and receiving special education. Materials and Methods

All participants completed the WAIS-III (UK) and WISC-IV (UK). The order of administration was counterbalanced; the mean Full Scale IQ and Index scores on the WAIS-III and WISC-IV were compared. Results

The WAIS-III mean Full Scale IQ was 11.82 points higher than the mean Full Scale IQ score on the WISC-IV. Significant differences were also found between the Verbal Comprehension Index, Perceptual Reasoning/Organization Index and Processing Speed Index on the WAIS-III and WISC-IV, all with the WAIS-III scoring higher. Conclusions

The findings suggest that the WAIS-III produces higher scores than the WISC-IV in people with intellectual disabilities. This has implications for definitions of intellectual disability and suggests that Psychologists should be cautious when interpreting and reporting IQ scores on the WAIS-III and WISC-IV.

Keywords: intellectual disability diagnosis; intelligence test; WAIS-III; WISC-IV

Technorati Tags: psychology, forensic psychology, forensic psychiatry, neuropsychology, intelligence, school psychology, educational psychology, IQ, IQ tests, IQ scores, intellectual disability, mental retardation, MR, ID, criminal psychology, criminal defense, ABA, American Bar Association, Atkins cases, death penalty, capital punishment, AAIDD, WAIS-III, WISC-IV, Wechsler batteries, psychometrics

IQ test selection could be life-or-death decision: WAIS v SB score differences in ID/MR sample

Interesting article "in press" in Intelligence that compares WAIS and Stanford Binet IQ scores (across different editions except the current SB5 and WAIS-IV) for adults with intellectual disability (ID/MR).  Although the mixing together of scores across different editions makes it impossible to make SB/WAIS-specific edition comparisons, the finding that the WAIS scores were, on the average (mean), almost 17 points higher may surprise many psychologists.  The authors discuss the real-life implications (i.e., Atkins ID death penalty decisions; eligibility for SS benefits, etc.) of different scores from different tests.  As outlined in a prior IAP AP101 special report, differences of this magnitude between different IQ tests should not be surprising. 

Silverman, W., Miezejeski, C., Ryan, R., Zigman, W., Krinsky-McHale & Urv, T. (in press).  tanford-Binet and WAIS IQ differences and their implications for adults with intellectual disability (aka mental retardation).  Intelligence.

Abstract

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.

A concluding comment from the authors

Nevertheless, psychologists cannot meet their ethical obligations in these cases without knowing which test provides the most valid estimate of true intelligence. The present data for individuals with relatively higher IQs, though sparse, indicate that differences between the Stanford-Binet and WAIS IQ tests can no longer be summarily dismissed as merely reflecting the scales' different floors. When test results are informing judgments of literal life and death, any suspected uncertainty regarding the validity of outcomes must be addressed aggressively.

Article Outline

1. Method
2. Results
3. Discussion

• 3.1. Disability determinations
• 3.2. Prevalence of ID
• 3.3. Declines with aging
• 3.4. Death penalty cases
• 3.5. Conclusion

Acknowledgements
References

Technorati Tags: psychology, educational psychology, school psychology, forensic psychology, court decisions, criminal psychology, criminal defense, Atkins cases, MR, ID, mental retardation, intellectual disability, death penalty, capital punishment, IQ, IQ scores, ABA, American Bar Association, ISIR, psychology and law, WAIS, Wechsler batteries, Stanford Binet, SB

Assessment issues: Malingering detection on WAIS-III and third-party testing observers

Research briefs regarding malingering assessment on WAIS-III in TBI and use of third-party observers during psychological assessment posted at ICDP sister blog

AP101 Brief #2: IQ test descriptive comparison information

AP101 # 2 Brief:  IQ test descriptive comparison information has been posted to sister blog ICDP.

APA Division 33: Intellectual and Developmental Disabilities Atkins related newsletter articles

In the past I mentioned (at ICDP sister blog) the importance of APA Divisions 33 (Intellectual and Developmental Disabilities) and 41 (American Psychology-Law Society) for psychologists and other professionals interested in Atkins cases. 

I recently joined both (although I've yet not received confirmation of my secret decoder ring and handshake for Div 33).

Today I was rummaging around the Div 33 website and was looking at past editions of the newsletter.  I found  that a large number of recent newsletters contained articles related to intellectual disability and Atkins cases.  I downloaded them for some late-night reading.  Others may find them of interest.  Below is a list of articles in recent newsletters.  You can access them by clicking here, and then using the "Current Issue" menu to locate specific issues.  Enjoy

• Vol 31 (2), 2006 - Division 33 Ad Hoc Committee on Mental Retardation and the Death Penalty by J. Gregory Olley, Stephen Greenspan and Harvey Switzky
• Vol 32 (1), 2006 - The Assessment of Adaptive Behavior in Adult Forensic Cases: Part 1 by J. Gregory Olley
• Vol 32 (3), 2006 - The Assessment of Adaptive Behavior in Adult Forensic Cases: Part 2. The Importance of Adaptive Behavior by J. Gregory Olley
• Vol 32 (3), 2007 - Capital Offenders and the Death Sentence: A Scandal That Must Be Addressed by James R. Flynn
• Vol 32 (3), 2007 - Flynn-Adjustment is a Matter of Basic Fairness by Stephen Greenspan
• Vol 33 (1), 2007 - The Assessment of Adaptive Behavior in Adult Forensic Cases: Part 3. The Importance of Adaptive Behavior by J. Gregory Olley
• Vol 33 (2), 2007 - 2007 Edgar A. Doll Address: “Why Mental Retardation and Intellectual Disabilities Are Important and Why Nobody Cares by Douglas K. Detterman
• Vol 33 (3), 2006 - Issues in the Use of the “Flynn Effect” to Adjust IQ Scores When Diagnosing MR by Stephen Greenspan
• Vol 34 (1), 2008 - Linguistic Sensitivity Does Not Require One to Use Grossly Deficient Norms: Why US Norms Should Be Used With the Mexican WAIS-III in Capital Cases by Hoi K. Suen and Stephen Greenspan
• Vol 35 (1), 2009 - Update on the Committee on Mental Retardation and the Death Penalty by J. Gregory Olley

Technorati Tags: psychology, APA, American Psychological Assoication, developmental disabilities, intellectual disabilities, mental retardation, APA Div 33, APA Div 41, Psychology and Law, adaptive behavior, intelligence, IQ tests, Flynn Effect, WAIS-III, WAIS-III Mexican norms

Research Bytes 10-23-08: RIAS/WAIS-III,Gv,imagery,neuropsychology,test norms

Articles that caught my eye during my weekly search of a wide range of professional literature.

Smith, B. L., McChristian, C. L., Smith, T. D., & Meaux, J. (2009). The relationshipo of the Reynolds Intellectual Assessment Scales and the Wechsler Adult Intelligence Scale-Third Edition. Perceptual and Motor Skills, 109(1), 30-40.

The purpose of this study was to compare scores on the Reynolds Intellectual Assessment Scales (RIAS) with scores on the Wechsler Adult Intelligence Scale-Third Edition (WAIS-III) in a group of college students diagnosed with a Learning Disability, Attention-Deficit Hyperactivity Disorder (ADHD), or a combination of the two. The RIAS Composite Index score was significantly higher than the WAIS-III Full Scale IQ, although scores on both tests were in the average range. Correlations between the two tests were significant on all measures. Male students were significantly higher than female students on both the RIAS Composite Index and on the WAIS-III Full Scale IQ. Although the ADHD group was higher on IQ than the Learning Disabled and combined disorder groups on all IQ measures, no significant differences were found.

Heilbronner, R. L., Sweet, J. J., Morgan, J. E., Larrabee, G. J., & Millis, S. R. (2009). American Academy of Clinical Neuropsychology Consensus Conference Statement on the Neuropsychological Assessment of Effort, Response Bias, and Malingering. Clinical Neuropsychologist, 23(7), 1093-1129.

During the past two decades clinical and research efforts have led to increasingly sophisticated and effective methods and instruments designed to detect exaggeration or fabrication of neuropsychological dysfunction, as well as somatic and psychological symptom complaints. A vast literature based on relevant research has emerged and substantial portions of professional meetings attended by clinical neuropsychologists have addressed topics related to malingering (Sweet, King, Malina, Bergman, & Simmons, 2002). Yet, despite these extensive activities, understanding the need for methods of detecting problematic effort and response bias and addressing the presence or absence of malingering has proven challenging for practitioners. A consensus conference, comprised of national and international experts in clinical neuropsychology, was held at the 2008 Annual Meeting of the American Academy of Clinical Neuropsychology (AACN) for the purposes of refinement of critical issues in this area. This consensus statement documents the current state of knowledge and recommendations of expert clinical neuropsychologists and is intended to assist clinicians and researchers with regard to the neuropsychological assessment of effort, response bias, and malingering.

Thompson, W. L., Slotnick, S. D., Burrage, M. S., & Kosslyn, S. M. (2009). Two Forms of Spatial Imagery: Neuroimaging Evidence. Psychological Science, 20(10), 1245-1253

Spatial imagery may be useful in such tasks as interpreting graphs and solving geometry problems, and even in performing surgery. This study provides evidence that spatial imagery is not a single faculty; rather, visualizing spatial location and mentally transforming location rely on distinct neural networks. Using 3-T functional magnetic resonance imaging, we tested 16 participants (8 male, 8 female) in each of two spatial imagery tasks—one that required visualizing location and one that required mentally rotating stimuli. The same stimuli were used in the two tasks. The location-based task engendered more activation near the occipito-parietal sulcus, medial posterior cingulate, and precuneus, whereas the transformation task engendered more activation in superior portions of the parietal lobe and in the postcentral gyrus. These differences in activation provide evidence that there are at least two different types of spatial imagery.

Dellatolas, G., Watier, L., LeNormand, M. T., Lubart, T., & ChevrieMuller, C. (2009). Rhythm Reproduction in Kindergarten, Reading Performance at Second Grade, and Developmental Dyslexia Theories. Archives of Clinical Neuropsychology, 24(6), 555-563.

Temporal processing deficit could be associated with a specific difficulty in learning to read. In 1951, Stambak provided preliminary evidence that children with dyslexia performed less well than good readers in reproduction of 21 rhythmic patterns. Stambak's task was administered to 1,028 French children aged 5–6 years. The score distribution (from 0 to 21) was quasi-normal, with some children failing completely and other performing perfectly. In second grade, reading was assessed in 695 of these children. Kindergarten variables explained 26% of the variance of the reading score at second grade. The Stambak score was strongly and linearly related to reading performance in second grade, after partialling out performance on other tasks (oral repetition, attention, and visuo-spatial tasks) and socio-cultural level. Findings are discussed in relation to perceptual, cerebellar, intermodal, and attention-related theories of developmental dyslexia. It is concluded that simple rhythm reproduction tasks in kindergarten are predictive of later reading performance.

Crawford, J. R., Garthwaite, P. H., & Slick, D. J. (2009). On percentile norms in neuropsychology: Proposed reporting standards and methods for quantifying the uncertainty over the percentile ranks of test scores. Clinical Neuropsychologist, 23(7), 1173-1195.

Normative data for neuropsychological tests are often presented in the form of percentiles. One problem when using percentile norms stems from uncertainty over the definitional formula for a percentile. (There are three co-existing definitions and these can produce substantially different results.) A second uncertainty stems from the use of a normative sample to estimate the standing of a raw score in the normative population. This uncertainty is unavoidable but its extent can be captured using methods developed in the present paper. A set of reporting standards for the presentation of percentile norms in neuropsychology is proposed. An accompanying computer program (available to download) implements these standards and generates tables of point and interval estimates of percentile ranks for new or existing normative data.

McGee, C. L., Delis, D. C., & Holdnack, J. A. (2009). Cognitive Discrepancies in Children at the Ends of the Bell Curve: A Note of Caution for Clinical Interpretation. Clinical Neuropsychologist, 23(7), 1160-1172.

Discrepancies between IQ scores on the Wechsler Abbreviated Scale of Intelligence (WASI) and scores from the Delis-Kaplan Executive Function System (D-KEFS) were examined at different levels of intellectual functioning in 470 normal-functioning youths (aged 8-19) from the co-standardization sample of the WASI and D-KEFS. Results demonstrated that children with lower IQ scores often had significantly higher D-KEFS scores, whereas children with higher IQ scores often had significantly lower D-KEFS scores. Similar patterns were identified for discrepancies between Verbal and Performance IQ indices. These findings are similar to those found in the adult literature. Clinicians are advised to be cautious when weighing the clinical significance of cognitive discrepancies at the ends of the bell-curve and should avoid interpreting discrepancies in isolation.

Technorati Tags: psychology, neuropsychology, educational psychology, school psychology, neuroscience, RIAS, WAIS-III, Wechsler, test norms, IQ tests, IQ, IQ scores, intelligence, IQs Corner, Research Bytes, malingering, Gv, visual-spatial, spatial imagery

AP101 Brief #1: g or not to g: IQ part vs full scale IQ scores in determining general intelligence

IQs Corner readers may find the Applied Psychometrics 101 Brief #1:  g or not to g in Atkins MR death penalty cases (post at sister blog) of interest.  Briefly, the two-post AP101 Brief presents and disucsses the relative g-loadings (g-ness) of composite scores from the WAIS-III, WJ III, and KAIT in a university adult sample. Questions are raised, based on analysis of data from a sample of 200 young adults, regarding the use of different composite scores from intelligence batteries in place of the total (full scale) IQ score when considerable variability exists in an IQ batteries composite scores.

Controversy re: use of Mexican WAIS-III in MR Atkins cases

See post at sister blog Intellectual Competence and the Death Penalty.

Technorati Tags: psychology, school psychology, educational psychology, neuropsychology, developmental psychology, forensic psychology, MR, Atkins cases, SCOTUS, WAIS-III, Mexican WAIS-III, IQ tests, IQ scores, test norms, psychometrics