are exciting times for those involved in research, development, and the use of intelligence
test batteries (McGrew, 1997, p. 172). This 1997 statement still rings true today.
Central to this
excitement has been the recognition and adoption, both within the theoretical and applied fields of
intelligence research and intelligence testing, of the Cattell-Horn-Carroll (CHC) theory of human
cognitive abilities (or some slight variation) as the definitive psychometric theory upon which to
construct a working taxonomy of cognitive differential psychology. Echoing Horn (1998) and
Jensens (2004) comparisons to the first presentation of Mendelyevs periodic table
in chemistry and Hans von Bülows there it is! declaration upon reading
the score of
Wagners Die Meistersinger, the order brought to the study, measurement, and assessment
human cognitive abilities by Carrolls (1993) synthesis, a synthesis built on the shoulders of
crowd of psychometric giants (Horn and Jensen included), has finally provided both intelligence
scholars and practitioners the first empirically-based consensus Rosetta stone from which to
organize research and practice. This is truly a marvelous development.
intelligence is clearly multidimensional. The past decade has witnessed the accumulation
of evidence that supports the broad strokes of the hierarchical multi-ability CHC theory of human
cognitive abilities. This new evidence, often derived from studies that gathered data with a wide
breadth of ability indicators in large nationally representative samples, validates the inclusion of
the broad (stratum II) abilities of Gf, Gc, Gq, Grw, Glr, Gsm, Gv, Ga, Gs, and Gt in the
taxonomy. In addition, past and recent research suggests the need to attend to, and possibly
incorporate, knowledge of additional broad domains (Gps, Gp, Gk, Gh, Gkn, and Go) in future
research, measurement, and assessment activities. Although not reviewed here in this chapter,
is also important to note that CHC theory is not based solely on factor analytic evidence.
Developmental, outcome-criterion prediction, heritability, and neurocognitive evidence add to the
network of validity evidence in support of contemporary CHC theory (see Horn & Noll, 1997).
with Carrolls (1994) self-critique and recommendations for future research, it is
important to recognize that the CHC framework is an open- ended empirical theory to which
future tests of as yet unmeasured or unknown abilities could possibly result in additional factors at
one or more levels in Carrolls hierarchy (Jensen, 2004, p. 5). The cognitive speed
research reviewed here serves as a cautionary tale that should ward off the tendency to succumb
to a premature hardening of the CHC categories. The importance of this caveat was
demonstrated this past decade vis-à-vis the structural research on the domain of cognitive mental
speed, where research now suggests a domain characterized by a complex hierarchical structure
with a possible g-speed factor at the same stratum level as psychometric g. In this
CHC taxonomy has been used as the open-ended framework described by Jensen (2004) and as
Carrolls (1994) intended guide and reference for future researchers (p. 22).
revisions, additions, and extensions to the CHC taxonomy suggested in this chapter are based
on a reasoned review and evaluation of research (primarily factor analytic) spanning the last
decade. It is hoped that the proposed CHC theory modifications proposed here enhance the
search for the holy grail of human cognitive ability taxonomies, at least by providing a
positive iteration towards convergence on a more plausible model. However, the proposed CHC
taxonomic enhancements summarized here require additional research and replication.
Reanalysis of Carrolls 460+ datasets with contemporary procedures (viz., confirmatory factor
analysis-CFA), combined with both CFA and Carroll EFA-based exploratory procedures of post-
Carroll (1993) datasets, will help elucidate the validity of current and future proposed revisions of
the CHC taxonomy.
although additional cautions and limitations could be enumerated, the seductive powers of
a neat and hierarchically organized structural diagram of cognitive abilities must be resisted.
theory that is derived primarily from a rectilinear system of factors is
not of a form that
describes natural phenomena (Horn & Noll, 1997, p. 84). By extension, assessment
professionals must humbly recognize the inherent artificial nature of assessment tools built upon
linear mathematical models. As stated by MacCallum (2003):
it is abundantly clear that psychological researchers
make extensive use of
mathematical models across almost all domains of research
It is safe to say that these
models all have one thing in common: The are all wrong. Simply put, our models are
implausible if taken as exact or literal representations of real world phenomena. They
cannot capture the complexities of the real world which they purport to represent. At
best, they can provide an approximation of the real world that has some substantive
meaning and some utility (p.114-115)
Carroll (1994, 1997) and Horn and Noll (1997) for excellent self-criticisms of the
CHC theory by the primary contemporary theory architects. ]