Cognitive Efficiency and achievement

The following article, which is "in press" in Intelligence, provides interesting information regarding the potential importance of measures of cognitive efficiency in predicting/explaining school achievement. The abstract is printed below along with a few highlights from the study.

Luo, D., Thompson, L. A., & Detterman, D. K. (2005). The criterion validity of tasks of basic cognitive processes. Intelligence, In Press, Corrected Proof.

Abstract

• The present study evaluated the criterion validity of the aggregated tasks of basic cognitive processes (TBCP). In age groups from 6 to 19 of the Woodcock-Johnson III Cognitive Abilities and Achievement Tests normative sample, the aggregated TBCP, i.e., the processing speed and working memory clusters, correlate with measures of scholastic achievement as strongly as the conventional indexes of crystallized intelligence and fluid intelligence. These basic processing aggregates also mediate almost exhaustively the correlations between measures of fluid intelligence and achievement, and appear to explain substantially more of the achievement measures than the fluid ability index. The results from the Western Reserve Twin Project sample using TBCP with more rigorous experimental paradigms were similar, suggesting that it may be practically feasible to adopt TBCP with experimental paradigms into the psychometric testing tradition. Results based on the latent factors in structural equation models largely confirmed the findings based on the observed aggregates and composites.

Summary/Comments

• The measures of TBCP in the present study were taken from two data sources, Woodcock-Johnson III Cognitive Abilities and Achievement Tests (W-J III; Woodcock et al., 2001a, 2001c; Woodcock, McGrew, & Mather, 2001b) normative data and the Western Reserve Twin Project (WRTP) data. The WJ III results will be the focus of this post.
• Luo et al. examined (via multiple regression and SEM) the extent to which measures of what the WJ III authors (myself included – see home page conflict of interest disclosure) call “cognitive efficiency” (CE - Gs and Gsm tests/clusters) add to the prediction of total achievement, above and beyond Gc and Gf.
• These researchers found that CE measures/abilities demonstrated substantial correlations with scholastic performance (WJ III Total Achievement). The CE-Ach correlations were similar to correlations between conventional test composites and scholastic performance. These results suggested that measures of CE provide incremental predictive validity beyond Gc. Collectively, CE+Gc accounted for approximately about 60% of the variability in achievement when observed measures were analyzed (multiple regression) and up to 70% or more of the variance when the SEM latent traits were analyzed. The authors concluded that these levels of prediction were “remarkable”
• Gf measures did NOT contribute significantly to the prediction of achievement beyond that already accounted for by the CE measures. [Editorial note – my prior research with the WJ III and WJ-R suggests this result may be due to the authors using “total achievement” as their criterion. My published research has consistently found that Gf is an important predictor/causal variable in the domain of mathematics].
• A potential explanation for the power of the CE measures/variables has previously been published and posted to the web (click here).
  
• The current results, IMHO, fit nicely within CHC-based information model frameworks that have been suggested. Simplified schematic models (based on the work of Woodcock) can be viewed by clicking here.