IQs Corner: What is (and what is not) clinical judgment in intelligence test interpretation?

What is clinical judgment in intelligence testing?  

This term is frequently invoked when psychologists explain or defend their intelligence test interpretations.  Below is a brief explanation I’ve used to describe what it is…and what it is not, based on several sources.  Schalock and Luckasson’s AAIDD Clinical Judgment book (now in a 2014 revised version) is the best single source I have found that addresses this slippery concept in intelligence testing, particularly in the context of a potential diagnosis of intellectual disability (ID)—it is a recommended reading.

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Clinical judgment is a process based on solid scientific knowledge and is characterized as being “systematic (i.e., organized, sequential, and logical), formal (i.e., explicit and reasoned), and transparent (i.e., apparent and communicated clearly)” (Schalock & Luckasson, 2005, p.1). The application of clinical judgment in the evaluation of IQ scores in the diagnosis of intellectual disability includes consideration of multiple factors that might influence the accuracy of an assessment of general intellectual ability (APA: DSM-5, 2013).  The “unanimous professional consensus that the diagnosis of intellectual disability requires comprehensive assessment and the application of clinical judgment” (Brief of Amici Curiae American Psychological Association, American Psychiatric Association, American Academy of Psychiatry and the Law, Florida Psychological Association, National Association of Social Workers, and National Association of Social Workers Florida Chapter, in Support of Petitioner; Hall v. Florida; S.Ct., No. 12-10882; 2014; p. 8).

The misuse of clinical judgment in the interpretation of scores from intelligence test batteries should not be used as the basis for “gut instinct” or “seat-of-the-pants” impressions and conclusions of the assessment professional (Macvaugh & Cunningham, 2009), or justification for shortened evaluations, a means to convey stereotypes or prejudices, a substitute for insufficiently explored questions, or an excuse for incomplete testing and missing data (Schalock & Luckasson, 2005). Idiosyncratic methods and intuitive conclusions are not scientifically based and have unknown reliability and validity. 

If clinical judgment interpretations and opinions regarding an individual’s level of general intelligence are based on novel or emerging research-based principles, the assessment professional must document the bases for these new interpretations as well as the limitations of these principles and methods. This requirement is consistent with the Standards for Educational and Psychological Testing Standard 9.4 which states:

When a test is to be used for a purpose for which little or no validity evidence is available, the user is responsible for documenting the rationale for the selection of the test and obtaining evidence of the reliability/precision of the test scores and the validity of the interpretations supporting the use of the scores for this purpose (p. 143).

American Educational Research Association, American Psychological Association, & National Council on Measurement in Education (2014).  Standards for educational and psychological testing.  Washington, DC:  Author. 

American Psychiatric Association (2013). Diagnostic and statistical manual of mental disorders— Fifth Edition. Washington D.C.:  Author. 

Brief of Amici Curiae American Psychological Association, American Psychiatric Association, American Academy of Psychiatry and the Law, Florida Psychological Association, National Association of Social Workers, and National Association of Social Workers Florida Chapter, in Support of Petitioner; Hall v. Florida; S.Ct., No. 12-10882; 2014; p. 8.

MacVaugh, G. S. & Cunningham, M. D. (2009). Atkins v. Virginia: Implications and recommendations for forensic practice.  The Journal of Psychiatry and Law, 37, 131-187.

Schalock, R. L. & Luckasson, R. (2005). Clinical judgment. Washington, DC: American Association on Intellectual and Developmental Disabilities. 

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Kevin S. McGrew, PhD.

Educational Psychologist

Director 

Institute for Applied Psychometrics (IAP)

www.theMindHub.com

Law Review Article: Evaluating Intellectual Disability: Clinical Assessments in Atkins Cases (Ellis et al., 2018)

This new law review article is, IMHO, the best overview article regarding the history of ID, the legal issues in Atkins cases, and good discussion of the major conceptual and measurement issues found in many Atkins cases. An excellent introduction to ID issues in Atkins cases.

EVALUATING INTELLECTUAL DISABILITY: CLINICAL ASSESSMENTS IN ATKINS CASES

James W. Ellis, Caroline Everington, Ann M. Delpha

ABSTRACT

The intersection of intellectual disability and the death penalty is now clearly established. Both under the U.S. Supreme Court's constitutional decisions and under the terms of many state statutes, individual defendants who have that disability cannot be sentenced to death or executed. It now falls to trial, appellate, and post-conviction courts to determine which individual criminal defendants are entitled to the law's protection. This Article attempts to assist judges in performing that task. After a brief discussion of the Supreme Court's decisions in Atkins v. Virginia, Hall v. Florida, and Moore v. Texas, it analyzes the component parts and terminology of the clinical definition of intellectual disability. It then offers more detailed discussion of a number of the clinical issues that arise frequently in adjudicating these cases. For each of these issues, the Article's text and the accompanying notes attempt to provide judges with a thorough survey of the relevant clinical literature, and an explanation of the terminology used by clinical professionals. Our purpose is to help those judges to become more knowledgeable consumers of the clinical reports and expert testimony presented to them in individual cases, and to help them reach decisions that are consistent with what the clinical literature reveals about the nature of intellectual disability and best professional practices in the diagnostic process.

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The Relation between Intelligence and Adaptive Behavior: A Meta-Analysis

Very important meta-analysis of AB IQ relation. Primary finding on target with prior informal synthesis by McGrew (2015)

The Relation between Intelligence and Adaptive Behavior: A Meta-Analysis   
 
Ryan M. Alexander 
 
ABSTRACT 
 
Intelligence tests and adaptive behavior scales measure vital aspects of the multidimensional nature of human functioning. Assessment of each is a required component in the diagnosis or identification of intellectual disability, and both are frequently used conjointly in the assessment and identification of other developmental disabilities. The present study investigated the population correlation between intelligence and adaptive behavior using psychometric meta-analysis. The main analysis included 148 samples with 16,468 participants overall. Following correction for sampling error, measurement error, and range departure, analysis resulted in an estimated population correlation of ρ = .51. Moderator analyses indicated that the relation between intelligence and adaptive behavior tended to decrease as IQ increased, was strongest for very young children, and varied by disability type, adaptive measure respondent, and IQ measure used. Additionally, curvilinear regression analysis of adaptive behavior composite scores onto full scale IQ scores from datasets used to report the correlation between the Wechsler Intelligence Scales for Children- Fifth edition and Vineland-II scores in the WISC-V manuals indicated a curvilinear relation—adaptive behavior scores had little relation with IQ scores below 50 (WISC-V scores do not go below 45), from which there was positive relation up until an IQ of approximately 100, at which point and beyond the relation flattened out. Practical implications of varying correlation magnitudes between intelligence and adaptive behavior are discussed (viz., how the size of the correlation affects eligibility rates for intellectual disability).
 
Other Key Findings Reported
 
McGrew (2012) augmented Harrison's data-set and conducted an informal analysis including a total of 60 correlations, describing the distributional characteristics observed in the literature regarding the relation. He concluded that a reasonable estimate of the correlation is approximately .50, but made no attempt to explore factors potentially influencing the strength of the relation.
 
Results from the present study corroborate the conclusions of Harrison (1987) and McGrew (2012) that the IQ/adaptive behavior relation is moderate, indicating distinct yet related constructs. The results showed indeed that the correlation is likely to be stronger at lower IQ levels—a trend that spans the entire ID range, not just the severe range. The estimated true mean population is .51, and study artifacts such as sampling error, measurement error, and range departure resulted in somewhat attenuated findings in individual studies (a difference of about .05 between observed and estimated true correlations overall).
 
 
The present study found the estimated true population mean correlation to be .51, meaning that adaptive behavior and intelligence share 26% common variance. In practical terms, this magnitude of relation suggests that an individual's IQ score and adaptive behavior composite score will not always be commensurate and will frequently diverge, and not by a trivial amount. Using the formula Ŷ = Ȳ + ρ (X - X ̅ ), where Ŷ is the predicted adaptive behavior composite score, Ȳ  is the mean adaptive behavior score in the population, ρ  is the correlation between adaptive behavior and intelligence, X is the observed IQ score for an individual, and X ̅ is the mean IQ score, and accounting for regression to the mean, the predicted adaptive behavior composite score corresponding to an IQ score of 70, given a correlation of .51, would be 85 —a score that is a full standard deviation above an adaptive behavior composite score of 70, the cut score recommended by some entities to meet ID eligibility requirements. With a correlation of .51, and accounting for regression to the mean, an IQ score of 41 would be needed in order to have a predicted adaptive behavior composite score of 70. Considering that approximately 85% of individuals with ID have reported IQ scores between 55 and 70±5 (Heflinger et al., 1987; Reschly, 1981), the eligibility implications, especially for those with less severe intellectual impairment, are alarming. In fact, derived from calculations by Lohman and Korb (2006), only 17% of individuals obtaining an IQ score of 70 or below would be expected to also obtain an adaptive behavior composite score of 70 or below when the correlation between the two is .50. 
 
 
The purpose of this study was to investigate the relation between IQ and adaptive behavior and variables moderating the relation using psychometric meta-analysis. The findings contributed in several ways to the current literature with regard to IQ and adaptive behavior. First, the estimated true mean population correlation between intelligence and adaptive behavior following correction for sampling error, measurement error, and range departure is moderate, indicating that intelligence and adaptive behavior are distinct, yet related, constructs. Second, IQ level has a moderating effect on the relation between IQ and adaptive behavior. The correlation is likely to be stronger at lower IQ levels, and weaker as IQ increases. Third, while not linear, age has an effect on the IQ/adaptive behavior relation. The population correlation is highest for very young children, and lowest for children between the ages of five and 12. Fourth, the magnitude of IQ/adaptive behavior correlations varies by disability type. The correlation is weakest for those without disability, and strongest for very young children with developmental delays. IQ/adaptive behavior correlations for those with ID are comparable to those with autism when not matched on IQ level. Fifth, the IQ/adaptive correlation when parents/caregivers serve as adaptive behavior respondents is comparable to when teachers act as respondents, but direct assessment of adaptive behavior results in a stronger correlation. Sixth, an individual's race does not significantly alter the correlation between IQ and adaptive behavior, but future research should evaluate the influence of race of the rater on adaptive behavior ratings. Seventh, the correlation between IQ and adaptive behavior varies depending on IQ measure used—the population correlation when Stanford-Binet scales are employed is significantly higher than when Wechsler scales are employed. And eighth, the correlation between IQ and adaptive behavior is not significantly different between adaptive behavior composite scores obtained from the Vineland, SIB, and ABAS families of adaptive behavior measures, which are among those that have been deemed appropriate for disability identification. Limitations of this study notwithstanding, it is the first to employ meta-analysis procedures and techniques to examine the correlation between intelligence and adaptive behavior and how moderators alter this relation. The results of this study provide information that can help guide practitioners, researchers, and policy makers with regard to the diagnosis or identification of intellectual and developmental disabilities.


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Research Byte: Psychological and Cognitive Aspects of Borderline Intellectual Functioning : A Systematic Review

Psychological and Cognitive Aspects of Borderline Intellectual Functioning: A Systematic Review

Contena, B., & Taddei, S. (2017). Psychological and Cognitive Aspects of Borderline Intellectual Functioning. European Psychologist. Article link.
 
Bastianina Contena and Stefano Taddei
 

Abstract:

Borderline Intellectual Functioning (BIF) refers to a global IQ ranging from 71 to 84, and it represents a condition of clinical attention for its association with other disorders and its influence on the outcomes of treatments and, in general, quality of life and adaptation. Furthermore, its definition has changed over time causing a relevant clinical impact. For this reason, a systematic review of the literature on this topic can promote an understanding of what has been studied, and can differentiate what is currently attributable to BIF from that which cannot be associated with this kind of intellectual functioning. Using Preferred Reporting Items for Systematic Review and Meta-Analyses( PRISMA) criteria, we have conducted a review of the literature about BIF. The results suggest that this condition is still associated with mental retardation, and only a few studies have focused specifically on this condition.
 
Keywords: borderline intellectual functioning, borderline mental retardation, intellectual disability, systematic review


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Sixth Circuit Court of Appeals rules against Flynn effect adjustment of IQ scores in Atkins death penalty cases: Black v Carpenter (2017)

A newly published 6th Circuit opinion (Black v Carpenter, 2017) rules against norm obsolescence (the Flynn effect) in the evaluation of IQ test scores in Atkins ID death penalty cases.  I obviously disagree with this decision as outlined in my 2015 chapter in the AAIDD "The Death Penalty and Intellectual Disability" (Polloway, 2015).

I have no further comment at this time as my expert opinion is clearly articulated in the AAIDD publication and I will continue my efforts to educate the courts.  This decision is at variance with the official positions of American Association on Intellectual and Developmental Disabilities (AAIDD) and the American Psychiatric Association (DSM-5), the two professional associations with official  guidance regarding  the diagnosis of ID. 

This looks like another issue that might need the attention of SCOTUS.

The following section is extracted from the complete ruling.


E. Implications of the Flynn Effect

There is good reason to have pause before retroactively adjusting IQ scores downward to offset the Flynn Effect. As we noted above, see n.1, supra, the Flynn Effect describes the apparent rise in IQ scores generated by a given IQ test as time elapses from the date of that specific test’s standardization. The reported increase is an average of approximately three points per decade, meaning that for an IQ test normed in 1995, an individual who took that test in 1995 and scored 100 would be expected to score 103 on that same test if taken in 2005, and would be expected to score 106 on that same test in 2015. This does not imply that the individual is “gaining intelligence”: after all, if the same individual, in 2015, took an IQ test that was normed in 2015, we would expect him to score 100, and we would consider him to be of the same “average” intelligence that he demonstrated when he scored 100 on the 1995-normed test in 1995. Rather, the Flynn Effect implies that the longer a test has been on the market after initially being normed, the higher (on average) an individual should perform, as compared with how that individual would perform on a more recently normed IQ test.

At first glance, of course, the Flynn Effect is troubling: if scoring 70 on an IQ test in 1995 would have been sufficient to avoid execution, then why shouldn’t a score of 76 on that same test administered in 2015 (which would produce a “Flynn-adjusted” score of 70) likewise suffice to avoid execution? Further, even if IQ tests were routinely restandardized every year or two to reset the mean score to 100, and even if old IQ tests were taken off the market so as to avoid the Flynn Effect “inflation” of scores that is visible when an IQ test continues to be administered long after its initial standardization, that would only mask, but not change, the fact that IQ scores are said to be rising.

Indeed, perhaps the most puzzling aspect of the Flynn Effect is that it is true. As Dr. Tassé states in his declaration, “[t]he so-called ‘Flynn Effect’ is NOT a theory. It is a wellestablished scientific fact that the US population is gaining an average of 3 full-scale IQ points per decade.” The implications of the Flynn Effect over a longer period of time are jarring: consider a cohort of individuals who, in 1917, took an IQ test that was normed in 1917 and received “normal” scores (say, 100, on average). If we could transport that same cohort of individuals to the present day, we would expect their average score today on an IQ test normed in 2017—a century later—to be thirty points lower: 70, making them mentally retarded, on average.

Alternatively, consider a cohort of individuals who, in 2017, took an IQ test that was normed in 2017 and received “normal” scores (of 100, on average). If we could transport that same cohort of individuals to a century ago, we would expect that their average score on a test normed in 1917 would be thirty points higher: 130, making them geniuses, on average.

It thus makes little sense to use Flynn-adjusted IQ scores to determine whether a criminal is sufficiently intellectually disabled to be exempt from the death penalty. After all, if Atkins stands for the proposition that someone with an IQ score of 70 or lower in 2002 (when Atkins was decided) is exempt from the death penalty, then the use of Flynn-adjusted IQ scores would conceivably lead to the conclusion that, within the next few decades, almost no one with borderline or merely below-average IQ scores should be executed, because their scores when adjusted downward to 2002 levels would be below 70. Indeed, the Supreme Court did not amplify just what moral or medical theory led to the highly general language that it used in Atkins when it prohibited the imposition of a death sentence for criminals who are “so impaired as to fall within the range of mentally retarded offenders about whom there is a national consensus,” 536 U.S. at 317. If Atkins had been a 1917 case, the majority of the population now living—if we were to apply downward adjustments to their IQ scores to offset the Flynn Effect from 1917 until now—would be too mentally retarded to be executed; and until the Supreme Court tells us that it is committed to making such downward adjustments, we decline to do so.

* * *

COLE, Chief Judge, concurring in the opinion except for Section II.E. I concur with the majority opinion except as to the section discussing the implications of the Flynn Effect. In holding that Black did not prove that he had significantly subaverage general intellectual functioning, we concluded that Black’s childhood IQ scores would be above 70 even if we adjusted those scores to account for both the SEM and the Flynn Effect. Accordingly, I would not address the question of whether we should apply a Flynn Effect adjustment in cases generally because it is unnecessary to the resolution of Black’s appeal. Regardless, courts, including our own in Black I, have regarded the Flynn Effect as an important consideration in determining who qualifies as intellectually disabled. See, e.g., Black v. Bell, 664 F.3d 81, 95–96 (6th Cir. 2011); Walker v. True, 399 F.3d 315, 322–23 (4th Cir. 2005).

Why full scale IQ scores are often much lower (or higher) than the part scores? Dr. Joel Schneider on the "composite score extremity effect"

Bingo.  There is finally an excellent, relatively brief, explanation of the phenomena of why full scale IQ scores often diverge markedly from the arithmetic average of the component index or subtest scores.

This composite score extremity effect (Schneider, 2016)  has been well known by users of the WJ batteries.  Why....because the WJ has placed the global IQ composite and the individual tests on the same scale (M=100; SD=15).  In contrast, most other cognitive ability batteries (e.g., Wechslers) have the individual test scores on a different scale (M=10; SD=3).  The use of different scales has hidden this statistical score effect from users.  It has always been present.  I have written about this many times.  One can revisit my latest post on this issue here.

Now that the WISC-V measures a broader array of cognitive abilities (e.g., 5 index scores), users have been asking the same "why does the total IQ score not equal the average of the index scores?"  Why?  Because the five index scores are on the same scale as the full scale IQ score...and thus this composite score extremity effect is not hidden.  A recent thread on the NASP Community Exchange provides examples of psychologists wondering about this funky test score issue (click here to read).

As per usual, Dr. Schneider has provided intuitive explanations of this score effect, and for those who want more, extremely well written technical explanations.

The WJ IV ASB 7 can be downloaded by clicking here.  Although written in the context of the WJ IV, this ASB is relevant to all intelligence test batteries that provide a global IQ score that is the sum of part scores.

Kudos to Dr. Schneider.

Click on image to enlarge

Race- or demographically-adjusted IQ norms are inappropriate in Atkins ID death penalty cases: New law review article by Robert Sanger

Previously, I coauthored an IAP Psychometric Brief (#14) with Dr. Dale Watson on the inappropriate use of "demographically adjusted norms" (aka, the Heaton norms) to adjust IQ scores upward based on an individuals race.  I was pleased last week to see a law review article devoted to this practice--an article that also concludes that the use of "ethnic" or "race" or "demographically" adjusted norms are inconsistent with scientific and legal principles.

The excellent American University Law Review article (IQ, INTELLIGENCE TESTS, “ETHNIC ADJUSTMENTS” AND ATKINS) is by Robert Sanger (click here to view).

ID is a "condition"...not a number. Ethics of IQ cut-off scores for ID Dx

Click on image to enlarge abstract.  Very thought provoking article (click to view) by Greenspan, Harris and Woods on the use of IQ cutoff scores to define ID.

Law Review Article: Advantages of DSM-5 in the Diagnosis of Intellectual Disability: Reducing Reliance on IQ Ceilings in Atkins (Death Penalty) Cases

Haydt, Greenspan, and Bhushan's (2014) recent law review article on the possible advantages of using DSM-5 in Atkins cases can be found here.

SCOTUS Hall v Florida Atkins ID update: Petitioners and Amicus Briefs--major focus on IQ "bright line" and SEM

The Atkins MR/ID case of Hall v Florida, which is to be heard by SCOTUS this spring, had two mportant briefs posted within the last week.

The Hall v Florida petition was filed Dec 16. Today, an Amicus Brief was filed by a number of organizations, led by the American Psychological Association.
Click here for a variety of posts re: Atkins cases in Flordia, which have been problematic due to the Florida "Cherry court" establishment of a "bright line" score of 70, with no consiseration of the standard error of measurement (SEM)

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Law Review Article: Defining intellectual disability and establishing a standard of proof: Suggestions for a national model standard

This article can be viewed here.

Click on images to enlarge. This article has been added to the Law Review blog roll.

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Hall v Florida Atkins ID SCOTUS review: ICDP prior comments re SEM and problems with Florida's Atkins criteria

The Hall v Florida Atkins case, which will be reviewed by SCOTUS, has been generating considerable buzz the past few days, including an editorial in the NY Times (Intellectual Disability and the Death Penalty - 10-22-13; image of editorial below--click to enlarge to read). 

This is a very important case given Florida's complete disregard for the scientific facts that underlie the psychometrics of intelligence tests--in favor of a "bright line" criteria that fails to account for the standard error of measurement (SEM) in IQ scores.

I have previously made a couple of posts re this problem in Florida.  These posts can be found here.  Together with Kevin Foley, I published an IAP Psychometrics 101 Report (#11) which addresses the issue of the SEM in Atkins cases.

I hope that SCOTUS will recognize the obvious scientific flaws in the Florida Atkins criteria.

(Click image to enlarge)

IAP AP101 Brief # 10: Understanding IQ score differences: Examiner Errors

Why do significant differences in IQ scores often occur between different tests or the same test given at different times? The explanations are many. Previous IAP Applied Psychometric 101 Reports and Briefs have touched on a number of reasons. Click here to view or link to these reports.

In the first AP101 report, which I would recommend reading prior to reading the material below, test administration and or scoring errors (examiner errors) were mentioned as a possible reason for score discrepancies. The brief report below addresses this topic.


Test procedural and administration errors (examiner error)

Despite rigorous graduate training in standardized administration of intelligence tests for most psychologists, the extant research on adherence to standardized administration and scoring procedures has consistently reported (unfortunately) that the frequency of examiner errors occurs with enough regularity, for both novice and experienced psychological examiners, to be a concern.

Ramos, Alfonso and Schermerhorn (2009) summarized the extant research on examiner errors and reported that most research studies reported sufficient average examiner error to produce significant changes in IQ scores for individuals. The most frequent types of errors reported included a failure to record responses, use of incorrect basal and ceiling rules, reporting an incorrect global IQ score, incorrect adding of subtest scores, incorrect assignment of points for specific items, and incorrect calculation of the individuals age. On Wechsler-related studies, Ramos et al.'s review found that studies have reported average error rates from 7.8 to 25.8 errors per test record, almost 90% of examiners making one error, and in one study 2/3 of the test records reviewed resulted in a change in the Full Scale IQ. Examiner errors do not appear instrument specific as Ramos et al’s reported an average error rate of 4.63 errors per test record on the WJ III Tests of Cognitive Abilities.

The importance of verifying accurate administration and scoring is evident in the finding that across experienced psychologists and students in graduate training, ranges of score differences were as high as 25, 22, and 11 points respectively for the WAIS-III Verbal, Performance and Full Scale IQ scores (Ryan & Schnakenberg-Ott, 2003). Despite examiners reporting confidence in their scoring accuracy, Ryan and Schnakenberg-Ott reported average levels of agreement with the standard (accurate) test record of only 26.3% (Verbal IQ), 36.8 % (Performance IQ), and 42.1 % (Full Scale IQ).

This level of examiner error is alarming, particularly in the context of important decision-making (e.g., IQ score-based life-and-death Atkins MR/ID decisions; eligibility for intervention programs; eligibility for social security disability funds). The level of examiner experience does not appear to be an explanatory variable. More recently, when investigating a single subtest (WISC-IV Vocabulary), Erodi, Richard and Hopwood (2009) reported that more errors may be present when evaluating low and high ability subjects.

Numerous test development and professional training and monitoring recommendations have been suggested (see Erodi et al, 2009; Hopwood & Richard, 2005; Kuentzel et al. 2011; Ramos et al., 2009; Ryad & Schnakenberg-Ott, 2003), some that have empirically demonstrated improvement in accuracy (see Kuentzel, Hetterscheidt &Barnett, 2011).

Examiner test administration and scoring errors can be the reason for discrepant IQ-IQ score differences. It is clear that before attempting to interpret any IQ scores, or trying to reconcile IQ-IQ score differences between tests, the first step would be for all examiners to double check their scoring. Another wise step would be to seek independent review of a scored test record by another experienced examiner. In the case of Atkins decisions, attempts should be made to secure copies of the original IQ test records for independent review. If any clear errors are present, they should be corrected and new scores recalculated. Only then should psychologists proceed to draw conclusions about the consistency or differences between scores from different IQ tests or versions of the same test given at different times during an individual’s life-span.

Any intelligence test results used in an Atkin’s hearings must be subject to independent review of the original test protocol (this may be impossible for old historical testing results) to insure against administration or scoring errors that might result in significant differences in the reported IQ score. This is critically important in Atkin’s cases were the courts often use a strict specific-IQ “bright line” cut score to determine the presence of an intellectual disability.

Below are the abstracts from the primary sources for this brief report. Double click on the images to enlarge.
























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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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Law Review Article: Mental retardation / intellectual ability and statutory rape (Nevins-Saunders, 2010)

Thanks to Kevin Foley for bringing this article to my attention. It is being added to the Law Review Article blogroll.

Double click on image to enlarge.



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Court Decision: Ramirez v Ryan (AZ, 2010)---follow up FYI

In the previous "So close, yet so far away--Or how the burden of proof matters" guest post by Kevin Foley the Atkins case of Ramirez v AZ raised a number of significant issues such as IQ practice effects, the Flynn effect, the burden of proof, preponderance of the evidence standard, etc (see prior post for more details). 

This past month a decision was made in the Ramirez v Ryan (AZ, 2010) federal habeas corpus case in the  Arizona District Court.  The decision outlines the complexity of a number of interesting and recurring issues (e.g., the Flynn Effect; practice effect) in Atkins cases, and the difficulty possed to the courts by dueling experts with differing opinions.    Due to a lack of time I will not make any additional comments.  This is an FYI post.

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Court Decision: Smith v TN (2010)

Still "cleanin' out my in box."

The Tennessee Court of Criminal Appeals rendered a very interesting (perplexing?) ruling recently. I only had time for a quick skim. With that caveat, the decision for Leonard Smith is available here. I will add it to the ICDP Court Decisions blog roll in the next day or so. Thanks again to the ever diligent Kevin Foley for sending this one my way.

Of interest is how the post conviction relief court dealt with a large number of IQ scores from ages 14 thru adulthood---tests that varied from comprehensive intelligence batteries to tests that were quick and limited screening instruments. Present in the document are the following scores. Those based on a comprehensive intellectual battery are designated by asterisks

1975 WISC 80*
1975 Ammons Quick Test 70
1976 Ammons Quick Test 84
1980 Un-named (prison) 88
1984 PPVT 86
1989 WAIS-R 75*
2001 WAIS-III 77*
2002 WAIS- III 65*


One troubling statement is on page 51:

“Specifically, the post-conviction court rejected the IQ scores achieved by [Smith] during his adult years and, apparently referencing the performance IQ achieved in 1975 when he was fourteen years of age, concluded that ‘testing preformed before the ate of eighteen reflects a functional I.Q. of 85.’”

Although there are individual cases were a component or sub-score index score may be the best estimate of a person's general level of intellectual functioning, in general, the overall "full scale" IQ should always be given first priority consideration in Atkins cases. I am baffled that given four different Wechsler Full Scale IQ scores a decision was made to "cherry pick" the Performance Scale IQ of 85 from the WISC administered when Smith was a teenager. How can all the adult scores simply be dismissd without an explanation?

In addition, the appeals court rejected the concepts of the standard error of measurement (SEM) and norm obsolescence (aka, the Flynn Effect) and stuck with the states supreme court and acknowledged, that by taking this approach, persons with MR/ID will be executed in Tennessee. Hmmmm? Atkins claim denied.

In the end, though, Smith got some relief based on his trial attorneys failure to get a judge recused.

Strange twists and turns.

Atkins cases death penalty capital punishment ICDP blog intelligence IQ scores IQ tests Wechsler batteries WISC WAIS WAIS-R WAIS-III screening IQ tests Smith v TN psychology school psychology neuropsychology forensic psychology ABA criminal justice


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New directions in neuropsychological assessment: Augmenting neuropsychological assessment with CHC cognitive measures

I just returned from Australia where I made a number of presentations.  Two were at the 2010 16th Annual APS College of Clinical Neuropsychologists Conference. 

I just posted the slides (at my SlideShare site - click here) from my 2+ hour workshop:  New directions in neuropsychological assessment: Augmenting neuropsychological assessment with CHC cognitive measures.

Briefly, the workshop is my first attempt to integrate CHC with neuropsychological assessment, with an emphasis on how NP tests can be interpreted from the CHC intelligence model which can then serves as a foundation for follow-up testing of NP tests with CHC measures.  Below are a few "tease" slides to get readers interested.  The last slide is derived from the keynote presentation I made (Beyond CHC theory...), which will be posted shortly.

Technorati Tags: Psychology, school psychology, developmental psychology, educational psychology, forensic psychology, neuropsychology, special education, intelligence, cognitive abilities, cognition, intelligence theories, CHC theory, CHC, Cattell-Horn-Carroll, intelligence, cognition, IQ, IQ tests

Court Decision: More on Mathis v Thaler (2005, 207, 2010, TX)

This is a follow-up to that quick FYI post I made Friday where I had received a note re: the denial of a federal habeas petition in an Atkin's related case (Mathis v Thaler, 2005, 2007).  Thanks to Kevin Foley, a fountain of legal knowledge and regular ICDP guest blogger, I now have a little more information regarding this case.

Clearly this decision demonstrates that perfecting and pursuing a federal habeas corpus claim is complicated.  As I now understand matters, The Fifth Circuit Court of Appeals previously had addressed Mathis' claim of MR/ID, but not in an Atkins context in  2005. At that time the court stated:

The evidence presented to the state trial court showed Mathis to have a low range of intelligence but all above the threshold for mental retardation. Specifically, the expert’s report indicated that Mathis’ full scale I.Q. was 79, his verbal I.Q. was 77 and his performance I.Q. was 85. Testing performed by a psychologist for the Texas Department of Criminal Justice after his conviction reflect different results. Those results show Mathis to have a full scale I.Q. of 62, verbal I.Q. of 65 and a performance I.Q. of 60. The district court held that Mathis failed to present evidence that reasonable counsel, at the time of trial, would have investigated his possible mental retardation further.

One may suspect the reasoning involved and greater insight requires examining the specifics of the intellectual testing history of Mathis.  According to the habeas corpus petition (p. 8-9)  Mathis' IQ of 79 was obtained on the WISC-R in 1991--- if a Flynn Effect "adjustment" had been invoked, the score should be approximately 70.  Hmmmm.....is it possible that the appeals court, which already dismissed the MR/ID claim in 2005 simply did not want to address it again?


Technorati Tags: psychology, forensic psychology, forensic psychiatry, neuropsychology, intelligence, school psychology, psychometrics, educational psychology, IQ, IQ tests, IQ scores, adaptive behavior, adaptive functioning, intellectual disability, mental retardation, MR, ID, criminal psychology, criminal defense, criminal justice, ABA, Atkins cases, Atkins death penalty, American Bar Association, Atkins cases, death penalty, capital punishment, AAIDD, Atkins MR/ID listserv, ICDP blog, psychiatry, psychiatry and criminal justice, Mathis v Thaler, Mathis v Texas, Flynn effect

Atkins MR/ID death penalty case a "notable petition" before SCOTUS. Hall v Thaler

Interesting potential SCOTUS development as reported at the SCOUTUS BLOG.  Hall v Thaler (previously listed here at ICDP as Hall v Quartermann;  has now been updated to be Hall v Thaler under the Court Decisions section to reflect recent developments) is reported to be a "notable petition"----which, according to the site, "indicates it is a case scheduled for consideration by the Justices."

The listing is under the notable petitions section of the SCOTUS blog, and includes links to filed background documents (5th Circuit opinion; Petition for certiorari;  Amicus brief of Texas State Senator Rodney Ellis et al; and Amicus brief of AAIDD and ARC.  The case is docket number 10-37.  I've only had time to skim a few pages but this Texas case appears to have the potential to raise a number of critical Atkin's issues---and provide SCOTUS with the chance to address some of the mess left post-Atkins.

Will monitor as close as possible.  Would appreciate others sending me FYI's as they learn and hear more.

Technorati Tags: psychology, forensic psychology, forensic psychiatry, neuropsychology, intelligence, school psychology, psychometrics, educational psychology, IQ, IQ tests, IQ scores, adaptive behavior, adaptive functioning, intellectual disability, mental retardation, MR, ID, criminal psychology, criminal defense, criminal justice, ABA, Atkins cases, Atkins death penalty, American Bar Association, Atkins cases, death penalty, capital punishment, AAIDD, Atkins MR/ID listserv, ICDP blog, psychiatry, psychiatry and criminal justice, Flynn effect, Briseno standards, Texas and death penalty, SCOUTS petition, Hall v Thaler