Tuesday, January 26, 2010

AAIDD intellectual disability manual (11th edition): Intelligence component -1 standard deviation below average: Final in 3-part series

This is my third (and final) comment in my series of comments re: the intellectual component of the new AAIDD ID/MR definition and classification manual.  I urge readers, if they have not done so, to read my original post.  In the first post I outlined the reason for the series.  I also highlighted positive features of the AAIDD component (chapter 4) of the manual and acknowledged that no manual will be perfect.  In the second post, I presented a comparative analysis of the literature cited in the 2002 and 2010 manuals regarding the nature and definition of intelligence. It was my conclusion that the 2010 manual (11th edition-the green book) failed to incorporate significant consensus-based advances regarding the nature of psychometric theories of intelligence and contemporary intelligence tests based upon these theories.

This final post is intended to provide the foundations for the conclusions in my second critical analysis post. To be honest, I've struggled with how to articulate these concerns in a brief format. This has been the major reason for the delay in this final post. I've struggled with not wanting to be a simple critic who does not offer substantive evidence or guidance. More importantly, I did not want to be a critic who did not try to help rectify the issues identified. Thus, I decided to take a more ambitious educational approach to my concerns regarding the AAIDD ID 2010 manual. Thus, my final post in the form of a lengthy PowerPoint presentation that is intended to educate and provide background information regarding my criticisms.

Below is a description of the PowerPoint presentation which is available via my SlideShare space.  This is an online  presentation that can also be downloaded to your respective hard drive for off-line viewing and use. In addition, I have made available a PDF copy of the slides presentation can be accessed by clicking here. [Warning....the PDF version is very large...30+MB....and should only be downloaded when you have a high speed connection]

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.

Below is my final set of critical summary comments (2nd slide from the end) presented at the end of the presentation.
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”.

As I stated in my original post, "ideally I hope that my forthcoming critical comments, combined with a spirited back-and-forth dialogue, will produce productive scholarly discourse, discourse that may result in AAIDD upgrading/revising their current written statement regarding the first prong of an ID diagnosis—intellectual functioning (Chapter 4) via new position papers or journal articles, web-based clarifications, and/or the publication of more specific professional guidelines."  Finally, I extend an invitation to members of the committee (that drafted the 2010 manual) to forward  me any professional responses to my series,  which I will post as "guest post responses" at the ICDP blog.

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