This is a shameless plug. An invited editorial I published in the journal Intelligence is now the number one cited article, since 2009. I believe this is a solid indicator that the CHC model of intelligence is now the most prominent psychometric model of intelligence and is in the mainstream of intelligence research. My mom and dad should be proud. Click here to review or download.
Click on image to enlarge
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. DiscussionAcknowledgements
- 3.1. Disability determinations
- 3.2. Prevalence of ID
- 3.3. Declines with aging
- 3.4. Death penalty cases
- 3.5. Conclusion
References
This study used the Woodcock-Johnson Tests of Cognitive Ability-Revised to investigate a wide range of cognitive abilities in people with Williams syndrome (WS). It involved a comparatively large sample of 31 people with WS, but took a case-series approach. The study addressed the widespread claims of a characteristic "WS cognitive profile" by looking for heterogeneity rather than homogeneity. People with WS showed a variety of preserved (significantly above mental age [MA]), expected (at MA), and significantly impaired (significantly below MA) levels of functioning. Such results provide clear evidence for heterogeneity in cognitive functions within WS. We found the most homogeneity on a test of phonological processing and a test of phonological short-term memory, with half of the WS sample performing at MA levels on these tests. Interestingly, no WS individual showed a weakness on a test of nonverbal reasoning, and only one WS individual showed a weakness on a test of verbal comprehension. In addition, we found that strengths on analysis-synthesis and verbal analogies occurred only for WS individuals with an MA less than 5.5 years (our sample median MA); people with an MA greater than 5.5 years performed at MA level on these 2 tests. Results also provided preliminary evidence for distinct subgroups of WS people based on their cognitive strengths and weaknesses on a broad range of cognitive functions. On the basis of the findings, caution should be made in declaring a single cognitive profile that is characteristic of all individuals with WS. Just as there is heterogeneity in genetic and physical anomalies within WS, not all WS individuals share the same cognitive strengths and weaknesses. Also, not all WS individuals show the profile of a strength in verbal abilities and a weakness in spatial functions.
Description of presentation: This presentation traces the evolution of psychometric theories of intelligence from Spearman's g to contemporary CHC. In addition, it simultaneously tracks the evolution of psychometric tests of intelligence as they relate to psychometric theories. Finally, there is a special emphasis on tracking changes in the AAMR/AAIDD intellectual disability (mental retardation) classification manuals over the same period. It is concluded that despite significant advances in psychometric theories of intelligence and contemporary psychometric intelligence tests, the official 2010 AAIDD manual is significantly behind these developments. The 2010 AAIDD manual is "stuck on g" and has failed to incorporate advances in both psychometric theories and tests of intelligence. A significant intelligence theory--AAIDD ID/MR definition gap exists tat has potential serious consequences for individuals with ID/MR.
Despite the widespread acceptance and recognition of the contemporary CHC (aka Extended Gf-Gc) theory of intelligence by intelligence scholars, a 2002 national panel of MR/ID experts, and the clear movement in applied IQ test development to test batteries grounded in the CHC framework, AAIDD continues to be “stuck on g”
The AAIDD definition of intelligence is out-of-date. A major intelligence theory—AAIDD ID definition gap exists
Contemporary intelligence scholars, experts, and test developers recognize that although g (general intelligence) may exist at the apex of the CHC taxonomy of human cognitive abilities, there are broad (stratum II) abilities that are important (i.e., have differential validities) that can be assessed and, when interpreted appropriately, can provide a more valid and multidimensional picture of an individuals intellectual functioning.
AAIDD’s continued use of the statement (with regard to measurement of multiple cognitive abilities) that “until such measures of multiple intelligences can be assessed reliably and validly, it is the position of AAIDD that intellectual functioning…is best conceptualized and captured by a general factor of intelligence” is simply wrong! Reliable and valid measures of the broad CHC ability domains exist and have been published in most intelligence batteries published from 1989 to 2008.
The AAIDD g-position is at odds with the known heterogeneity of abilities within the ID (and general) population and fails to recognize that although a g-based total composite score may often represent the best single index of a person’s intellectual functioning, often the g-based composite score may lead to inaccurate conclusions regarding a person’s intellectual functioning and in these cases more attention should be focused on the component part scores. The stuck on g position has the potential to result in serious consequences for individuals, such as denial of special education services; denial of SS benefits, and unjust execution as in “Atkins MR/ID death penalty cases”.
It is well-established that schools were and are reluctant to classify children as mentally retarded, particularly African-American students since the 1970s (MacMillan & Siperstein, 2002). Schools frequently assign a more ‘‘palatable’’ label to students who would otherwise be classified as mentally retarded, using labels such as ‘‘specific learning disability’’ or ‘‘speech and language impairment.’’ In Atkins cases, this frequently works against the defense’s efforts because there is no developmental history of an individual ever being diagnosed as mentally retarded, thereby making it difficult to prove the developmental criterion of mental retardation.(p.9).Second, there has been a long-held (mistaken) assumption, both in the lay public and with many professionals who do intelligence testing, that a person's IQ score sets a limit on their academic learning. That is, because of their limited intellectual ability (IQ), one cannot expect these individuals to achieve at levels above their measured IQ. This is a false assumption.
Gresham, F. M. (2009). Interpretation of Intelligence Test Scores in Atkins Cases: Conceptual and Psychometric Issues. Applied Neuropsychology, 16, 91-97
“John Carroll has done a magnificent thing. He has reviewed and reanalyzed the world’s literature on individual differences in cognitive abilities…no one else could have done it… it defines the taxonomy of cognitive differential psychology for many years to come.”
Carroll’s book “is simply the finest work of research and scholarship I have read and is destined to be the classic study and reference work on human abilities for decades to come” (p. 35).
A “tour de force summary and integration” that is the “definitive foundation for current theory” (p. 58). Horn compared Carroll’s summary to “Mendelyev’s first presentation of a periodic table of elements in chemistry” (p. 58).Jensen, A. R. (2004). Obituary - John Bissell Carroll. Intelligence, 32(1), 1-5.
“…on my first reading this tome, in 1993, I was reminded of the conductor Hans von Bülow’s exclamation on first reading the full orchestral score of Wagner’s Die Meistersinger, ‘‘It’s impossible, but there it is!’’
“Carroll’s magnum opus thus distills and synthesizes the results of a century of factor analyses of mental tests. It is virtually the grand finale of the era of psychometric description and taxonomy of human cognitive abilities. It is unlikely that his monumental feat will ever be attempted again by anyone, or that it could be much improved on. It will long be the key reference point and a solid foundation for the explanatory era of differential psychology that we now see burgeoning in genetics and the brain sciences” (p. 5).
Eric Lynn Moore, an African American inmate under a sentence of death, sought to escape the death penalty by invoking Atkins. The federal district court ruled in Moore’s favor, exempting him from the death penalty. The state appealed. According to the Fifth Circuit Court of Appeals, Moore obtained the following IQ scores: a 76 on the WAIS-R; a 66 on the WAIS-III; and a 74 on the Primary Mental Abilities test. Moore also scored in the bottom eight-tenths of a percentile on the TONI-2. The dissenting opinion in Moore states that the PMA was given to Moore when he was in the first grade; the WAIS-R was given to Moore, in prison, in 1991; and the WAIS-III was given to Moore in 2004. The district court resolved the issue of Moore’s current intellectual functioning by averaging the three scores to come up with an average score of 72, to which he applied the standard error of measurement. The appeals court approved this approach, stating, “In averaging the test scores and relying on the five-point margin of error . . . the district court attempted to find a way to reconcile all three test scores.”
The lone dissenting judge issued a scathing dissent, including biting comments accusing the majority of using “[h]aphazardly-applied standards of review, casually-read case law, and superficially-scrutinized evidence [which] make for an unfortunate combination; here, they result in shallow analysis and the wrong result. The only mitigation is that the majority opinion is unpublished, so it is not binding on anyone or any court.” Ouch!
The dissent correctly, in my opinion, took the trial and appeals courts to task on the issue of using an average of IQ scores from as far back as 1973 to determine current level of functioning. First, the trial court neglected to address issues surrounding the accuracy of the three scores. According to the dissent,
“All three of those test results were called into question at the evidentiary hearing. The PMA score, for example, is only a number; there is no evidence that it was properly scored or whether it was administered individually, as the test protocol requires, or to an entire school class. The vocabulary section of the WAIS-R, according to [defense expert] Llorente, was improperly scored, and in a way that may have slightly inflated the score. Llorente also testified concerning the ‘Flynn Effect,’ the apparent increase in the average IQ scores in populations over time, as measured by a given IQ test. Because the WAIS-R was an older test when it was administered to Moore, Llorente suggested adjusting Moore’s score of 76 downward by about four points.”
In addition, the state’s expert asserted that Moore’s expert improperly scored the WAIS-III test. The dissent correctly complained that the trial court took the easy way out by averaging the scores.
“Instead of grappling with those conflicting upward and downward adjustments, the district court gave the three scores equal weight, averaged them, reached an IQ of 72, applied the ‘five-point standard error of measurement,’ and therefore concluded that Moore had borne his burden of proof. It is that finding, and the district court’s actual reasoning in making it, that the panel must consider, and yet the majority refuses to address it at anything resembling an acceptable level of detail. . . .
“For one thing, there is no legal or record support for taking an average of Moore’s IQ scores. Averaging IQ scores is, to say the least, a creative approach to their analysis and comparison and is highly unusual. Neither expert suggested, employed, or endorsed it. The district court assumed, without any evident backing, that averaging is a meaningful way to compare scores from different IQ testing protocols administered years apart and that the margin of error was the same for all three and was the same after the averaging as before. All of those assumptions are facially implausible, and the district court had no apparent reason to think any of them is correct.”
Although the dissent erred in other respects (some of which may make for other interesting blog entries), it hit the nail on the head on this issue. Although these issues – assertions of invalid results, mis-scoring of tests, application of the Flynn Effect, and determining what weight to give to certain evidence - might be complicated and hard to resolve, that is what courts do. They should educate themselves and use the experts to provide the information necessary to properly decide the case. Moreover, federal judges can appoint an independent expert to offset the parties experts, it the judge feels the need for some impartial testimony to help guide the court.
Posted with Blogsy