Wednesday, January 26, 2011

Blending neuropsychological and CHC psychometric IQ approaches to psych testing

Here is more on my take on how neuropsychological and CHC-based psychometric approaches to assessment can be understood and potentially blended. This is material from my keynote presentation at the Australian Neuropsychology Conference (click here for more information and a link to the PPT of the entire presentation).

Note: Images are embedded in this post. It should be possible to enlarge them by double clicking on each. If that does not work I would suggest you go to the link above and see the entire PPT show, which you can download for free.

​CHC-based neuropsychologists have integrated CHC theory into assessment practice based largely on theoretical, non-CHC empirical research, or logical analysis. Empirical CHC-based neuropsychological assessment research has been sparse. The CHC psychometric-neuropsychological assessment gap is understandable given the two respective assessment models and distinct historical backgrounds. Hoelzle (2008) noted that: (a) the psychometric concept of g has had minimal clinical utility in neuropsychological assessment and theory, (b) neuropsychological assessment has been primarily atheoretical while psychometric research has been searching for the “holy grail” theoretical structural model of intelligence since the days of Spearman, and (c) psychometric models have been primarily focused on internal structural validity while neuropsychological assessment has focused more on the practical questions regarding the ability to differentiate between neurological and normal conditions. McGrew (2010a) described these different approaches as a difference between vertical (factor analysis) trait-oriented psychometric models and more horizontal (multiple regression) functional/pragmatic external prediction neuropsychological models. These two approaches are demonstrated visually below in the two slides.

​As result of its pragmatic functional heritage, many neuropsychological assessment tests are mixed measures of multiple CHC domains. In the language of psychometric CHC Theory, many neuropsychological tests are factorially complex measures with considerable construct-irrelevant variance (when measurement of pure CHC constructs is the criterion). This contrasts with the strong emphasis in contemporary CHC intellectual assessment on developing tests that primarily measure one single CHC construct, purged as much as possible of non-relevant construct variance.

​In the absence of CHC-grounded neuropsyhological assessment research and a consensus neuropsychological assessment model, psychometric (e.g., Flanagan, Alfonso, Ortiz & Dynda, 2010; McGrew, 2010a) , neuropsychological (Strauss et al., 2006), and “blended” neuropsychological+psychometric oriented scholars (e.g., Hale & Fiorello, 2004; Miller, 2007, 2010) have, at times, presented significantly different interpretations of neuropsychological or intelligence tests. For example, more neuropsychologically oriented researchers have described the copy and recall components of Rey-Osterrieth Complex Figure (ROCF) test (Meyers & Meyers, 1995, 1996) as measuring planning and organizational abilities, visual memory, visual perception, constructional abilities, motor or visual-motor ability, episodic memory, and incidental learning (Hale & Fiorello, 2004; Straus et al., 2006). Hints of CHC terminology are present in some of these terms but there is no direct mapping to CHC Theory.

Conversely, starting with the results of Hoezle’s (2008) CHC-organized mini-Carroll like meta-analysis of the results of secondary factor analysis of 77 datasets that included neuropsychological and other ability measures (this is one of the best and most comprehensive dissertations I have ever read), McGrew (2010a) suggested that the copy component of the ROCF was likely a mixed measure of Gv-SR (narrow CHC ability of spatial relations in the broad Gv or visual-spatial domain), Gp-P2 (narrow CHC ability of finger dexterity in the broad Gp or psychomotor domain), with possible visual memory (Gv-Mv) involvement. As for the ROCF recall component, McGrew (2010a) suggests that it likely measures a mixture of Gv-MV (narrow CHC visual memory in the broad Gv domain), Glr-M6 (narrow CHC free recall ability in the broad Glr or long-term storage and retrieval domain), with possible involvement of working memory (Gsm-MW). Miller (2010) provides the “blended” interpretation of the ROCF as primarily a measure of visual-perceptual organization, visual-spatial ability and visual-spatial memory (Gv) in particular. Obviously the three sets of ROCF interpretations mention a number of similar abilities, yet practitioners are likely left confused given the varying terminology and ability descriptions.

My CHC neuropsych summaries for the ROCF are presented below:

- iPost using BlogPress from my Kevin McGrew's iPad