Wednesday, August 13, 2008

Some CHC specific abilities are important in school learning: Reflections on the g+specific abilities research

[Double click on image to enlarge]

Back in 1997, I, together with Dawn Flanagan, Tim Keith and Mike Vanderwood, published our first g+specific--->achievement article in School Psychology Review. I recently searched high and low for a pdf copy of this article via the usual library sources but came up blank. I finally scanned a copy into a pdf file. A copy of this article can be viewed by clicking here.

Included in that article was the figure to the right (double click to enlarge the figure). I've always liked this figure as it laid out the reasoning why the "just say no" (to intelligence test subtest analysis) research needed to be revisited in light of advances in: (a) theories of intelligence (CHC theory), (b) measurement of intelligence constructs (Gf-Gc or CHC-grounded batteries), and (c) statistical methodology (SEM vs multiple regression). The figure summarizes much of the introductory text in the 1997 article. Frankly, this publication is one of those for which I'm the most proud. Why?

First, the results demonstrated that some specific abilities are important in understanding reading and math achievement above and beyond the effect of g (general intelligence). IMHO this was a very important finding...and led us to argue for the "just say maybe" position (re: interpretation of strength and weakness profiles of cognitive tests---where the S/W measures where composites of at least 2 tests---cluster scores). Even Dr. Dan Reschly, someone typically associated with the anti-IQ movement in school psychology, in a response article in the same special SPR issue, stated (with regard to our 1997 article) :
  • “The arguments were fairly convincing regarding the need to reconsider the specific versus general abilities conclusions. Clearly, some specific abilities appear to have potential for improving individual diagnoses. " (Reschly, 1997, p.238).
Second, this "mother" study lead to a systematic program of g+specific abilities research that continues to suggest that certain broad/narrow CHC abilities are important in understanding reading and math achievement above and beyond the effect of g (general intelligence). A listing of articles that followed can be found by clicking here. Click here if you want to view all g+specific abilities posts that have been made at IQ's Corner. There are now a sufficient number of these studies, that when combined with CHC no-g model multiple regression studies, that I was able to recently complete the formative work on a research synthesis (CHC Cognitive-Achievement Correlates Meta-Analysis Project) of the collective findings (which I will eventually be summarizing in a manuscript). A review of all studies continue to support the "just say maybe" position.

Interestingly, although not dealing with reading and math achievement, a recent article in the prestigious journal Intelligence provided additional support for the g+specific "just say maybe" position. The CHC-organized article by Reeve (2004) demonstrated that specific cognitive abilities are indeed important (above and beyond the effect of g) in understanding and explaining the development of domain-specific knowldge (Gkn). The Reeve article provides an excellent review of the literature and, in many respects, reflects (and extends and augments) the arguments we made in our original 1997 article. I urge those interested in the g+specific abilities debate to carefully read Reeve's literature well as his findings. The Reeve findings are important given the extremely large size of the sample (n = 300,000+ from the famous PROJECT TALENT project)

Finally, I would be remiss if proper credit was not given to the "grandmother" article that first stimulated our (McGrew et al., 1997) initial g+specific abilities project, and which also appeared to play a noticeable role in the Reeve (2004) study. Our original research was started after reading the following article:
  • Gustafsson, J. -E., & Balke, G. (1993). General and specific abilities as predictors of school achievement. Multivariate Behavioral Research, 28, 407–434. (click here to view)
Enough said for now. I believe that a sufficient body of research evidence now exists that demonstrates there is more to understanding acquired knowledge acquisition and school achievement than g (general intelligence). When utilizing an appropriately valid and comprehensive model of intelligence (CHC theory) and appropriately designed and analyzed models, certain specific broad or narrow specific abilities are found to be important...and their effect sizes are not trivial. There is more to understanding school functioning than a simple full scale g-type score.

Of course, if one does not believe in the construct of g (e.g., John Horn's adamant position), then narrow and broad CHC abilities are found to be even more important (as reflected in the non-g CHC organized multiple regression studies integrated in the above mentioned research synthesis). However, that is another post (or series of posts).

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