An interesting finding in the Carroll Analyses of 50 CHC-designed tests (see 3-17 & 3-18-05 posts) is the emergence of separate cognitive (Gsc) and achievement (Gsa) factors, a distinction I have not found (although it may be out there somewhere) in the human cognitive abilities literature. Does this distinction make sense? I think so.
First, one potential distinction between the Gsc and Gsa factors/abilities may be a content facet dimension. The two strongest Gsc tests (Pair Cancellation and Visual Matching), as well as three of the four highest loading Gsc tests, require individuals to process visual/figural stimuli (e.g., numbers, pictures, shapes). In contrast, the two strongest Gsa tests (Reading Fluency and Writing Fluency) primarily require the processing of language or semantic material (words, sentences). Could the Gsc/Gsa factors reflect differential efficiency in the processing of information along a visual/spatial/figural—auditory/linguistic dimension?
Second, Newland’s classic process- vs. product-dominant distinction might also help understand the emergence of these two separate factors. The Gsa factor could be considered the fluency/rate indicator for the processing of more product-dominant (acquired knowledge) information and stimuli while Gsc may be associated with more process-dominant information processing. More specifically, the Gsa ability requires searching efficiently through an individual's store of acquired knowledge (e.g., achievements) while, in contrast, the Gsc stimuli are more novel and most likely require little in the way of acquired knowledge domain searches.
It is clear that much additional research is needed within the domain of human cognitive speed. A recent review of literature (published since Carroll’s 1993 treatise) has suggested a possible hierarchical speed model (click here) with at least three different strata, and possibly four or more. In that proposed hierarchy, even Perceptual Speed (P – an ability classified at stratum I – a narrow ability) has recently been suggested (by Ackerman et al) to have a substructure of yet narrower abilities (Pattern Recognition, Scanning, Memory, Complex).
Clearly the broad domain of human cognitive speed is not yet clearly defined and much is yet to be learned. If there are any doctoral students looking for dissertation topics, this CHC domain is still ripe for potential unique scholarly contributions…..just hurry up and do the research (Gs.phd – PhD processing speed).
Do others have hypotheses to explain and define the Gsa and Gsc factors identified in these analyses? The IQ blogsters are all ears.