collective influence of the Cattell-Horn Gf-Gc theory, Carrolls (1993) treatise, and the
publication of the Cattell-Horn Gf-Gc based WJ-R was reflected by nine chapters either being
devoted to, or including significant treatment of, the Cattell-Horn Gf-Gc and/or Carroll three-
stratum theories in Flanagan, Genshaft and Harrisons (1997) edited volume Contemporary
intellectual assessment: Theories, tests, and issues, a publication which, in turn, was also
major theory-to- practice bridging event (see section E3 in Table 1) for three reasons.
the CIA was the first book intended for university trainers and assessment practitioners that
included chapters describing both the Cattell-Horn and Carroll models by the theorists themselves
(Horn and Carroll). For those unfamiliar with the Horn Gf-Gc theory chapter in the
technical manual (McGrew et al., 1991), the CIA book provided a long overdue introduction of
the state-of-the- art of contemporary psychometric theories of intelligence to the professional
keepers of the tools of the intelligence testing trade (e.g., school psychologists).
McGrew and Flanagan, while digesting the implication of the need for 3-S vision (as
articulated by Carroll), and collaborating on a WJ-R/KAIT cross-battery confirmatory factor
analysis study (see Flanagan & McGrew, 1998), realized that the prior Gf-Gc test classifications
(Woodcock, 1990) described tests only at the broad or stratum II level, and they needed to be
taken down to the next levelto stratum I or the narrow ability level. In order to
do so, a single
taxonomy was needed. Rather than picking Cattell-Horn or Carrolls model over the other,
Synthesized Carroll and HornCattell Gf-Gc framework (McGrew, 1997) was developed
based on both Horn and Carrolls writings and a review of a previously unpublished exploratory
Schmid-Leiman factor analysis of the WJ-R completed by Carroll (see section F1 in Table 1).
included in the CIA was the first formal description of the assumptions, foundations, and
operationalized set of principles for Gf-Gc cross-battery assessment (Flanagan & McGrew,
1997; see section F2 in Table 1). The cross-battery seed planted by Woodcock (1990)
birth. The subsequent spreading of the assessment gospel as per Gf-Gc cross-battery
(Flanagan & McGrew, 1997; McGrew & Flanagan, 1997; Flanagan et al., 2000; Flanagan &
Ortiz, 2001; Flanagan, Ortiz, Alfonso & Mascolo, 2002; see section F4-F6 in Table 1) infused Gf-
Gc theory into the minds of assessment practitioners and university training programs, regardless
of their choice of favorite intelligence battery (e.g., CAS, DAS, K-ABC, SB4, WISC-III). The
formalization of Gf-Gc cross- battery assessment, primarily as the result of the work of Flanagan,
was another significant theory- to- practice bridging event. Daniel (1997) described the cross-
battery approach as intriguing and creative work now being done to integrate and interpret
cognitive batteries within the framework of a single multifactor model (p. 1043).
cross-battery assessment did not discriminate among test kits based on test name,
heritage, publisher, type or color of carrying case, prominent authors (dead or alive), or presence
or absence of manipulatives or a performance scale. The cumulative impact of the introduction
of Gf-Gc cross- battery assessment, following on the heels of the 1989 publication the Gf-Gc
organized WJ-R and Carrolls 1993 principia, established a Gf-Gc theory foothold in the
applied intelligence testing. The intelligence theory-to-practice gap had narrowed fast.
tipping point had been reached. [Note. The tipping point is the moment of critical
threshold, the boiling point (Gladwell, 2000, p.12) where a movement, which has been building
generally in small groups and networks, begins to influence a much wider audience]
derivation of the name Cattell-Horn-Carroll (CHC) theory remains a mystery to many.
the best of this authors knowledge, the first formal published definition of CHC theory was
presented in the WJ III technical manual (see McGrew & Woodcock, 2001; see section F5 in
Cattell-Horn-Carroll theory of cognitive abilities.
An amalgamation of two similar
theories about the content and structure of human cognitive abilities (J. B. Carroll & J.
L. Horn, personal communication, July 1999). The first of these two theories is Gf-Gc
theory (Cattell, 1941; Horn, 1965) and the second is Carrolls (1993) three- stratum
theory. CHC taxonomy is the most comprehensive and empirically supported
framework available for understanding the structure of human cognitive abilities (p. 9).
first published record of the hyphenated linking of Cattell- Horn-Carroll is in Flanagan et al.
(2000), were it was stated that a first effort to create a single Gf-Gc taxonomy for use
evaluation and interpretation of intelligence batteries was the integrated Cattell-Horn- Carroll
model (McGrew, 1997) (p. 28). Despite the foothold Gf-Gc theory had achieved in the field
applied intelligence testing prior to 1999, the term Gf-Gc was often meet with puzzled
recipients of psychological reports, sounded esoteric and non-meaningful, and continued to
unintentionally convey the inaccurate belief that the theory was a two-factor model (Gf and Gc),
despite the fact that it had evolved to an 8-9 broad ability model. Having dealt with this
communication problem since the publication of the WJ-R in 1989, Woodcock, together with the
Stanford Binet Intelligence ScalesFifth Edition (SB5; Roid, 2003) author, and staff from
Riverside Publishing, meet with Horn and Carroll during a private meeting in Chapel Hill, NC, to
seek a common, more meaningful, umbrella term that would recognize the strong structural
similarities of their respective theoretical models, yet also recognize their differences. Woodcock
engaged Horn and Carroll in a sequence of conversations that resulted in a verbal agreement that
the phrase Cattell-Horn-Carrroll Theory of Cognitive Abilities made significant practical
and, appropriately recognized the historical order of scholarly contribution of the three primary
contributors (see section E4 in Table 1). That was it. CHC emerged from private personal
communications in July, 1999, and seeped into subsequent publications.
theory represents both the Cattell-Horn and Carroll models, in their respective splendor.
Much like the phrase information processing theories or models, which provides an
overarching theoretical umbrella for a spectrum of very similar (yet different) theoretical model
variations (Lohman, 2001), CHC theory serves the same function for the variations on a Gf-Gc
theme by Cattell-Horn and Carroll, respectively. Table 2 compares and contrasts
similarities and differences between the Cattell- Horn Gf-Gc and Carroll three- stratum models.
As described above, the CHC model (Figure 1e) used extensively in applied psychometrics and
intelligence testing during the past decade is a consensus model. The specific organization and
definition of broad and narrow CHC abilities is summarized in Table 3.
the next section, a review of the CHC-related structural factor analytic research published
during the past decade is presented. The purpose of this review is to help the field iterate towards
a more complete and better understanding of the structure of human cognitive abilities.
Carroll recognized the CHC umbrella terminology in his last publication (2003), although he also was
a bit puzzled over the details of the origin of so-called CHC (Catell-Horn-Carroll) theory of
abilities (p. 18). According to Carroll (2003), even though I was to some extent involved
in this change (as
an occasional consultant to the authors and publisher), I am still not quite sure what caused or motivated
it (p. 18). In a personal conversation with this author and Jack Carroll regarding this
topic (at his
daughters home in Fairbanks, Alaska on 5- 26-03), Carroll recognized the practical rational for the
umbrella term, but was planning to make it clear in the revision of his 1997 CIA chapter that although
CHC umbrella term may make practical sense, he felt strongly that human cognitive abilities consisted
least three strata and that, in contrast to Horns position, that g exists. He believed
his last chapter
publication (2003) provided convincing evidence for the existence of g. Carroll wanted
to make it clear that
the overarching CHC umbrella did not reflect his agreement with Horn on all aspects of the structure
human cognitive abilities.]