Page 54 - Psychological Management of Individual Performance

general cognitive ability and job knowledge 33
of experience and ability on job performance. Results obtained provided support for the
validity of ability as a predictor of job knowledge, which in turn exerted a direct influence
on job performance.
A third stream of research derives from recent work by Ackerman and his colleagues
(Ackerman, 2000; Beier & Ackerman, 2001; Rolfhus & Ackerman, 1999). Ackerman
proposed a conceptualization of adult intelligence that appears to take account of the
distinctive influences of cognitive ability and knowledge on action. Ackerman’s PPIK
theory (see Ackerman, 1996, for a complete description) recasts adult intelligence as
an investment function of Process, Personality, and Interests, which lead to individual
differences in Knowledge. In contrast to research conceptualizing individual differences
in general intelligence as a unitary factor (Spearman’s g), Ackerman draws upon and
extends previous theory and research by Cattell and Horn (e.g., Cattell, 1963; Horn &
Cattell, 1966) that distinguishes between two dimensions; namely fluid (Gf) and crys-
tallized (Gc) intelligence. In the Cattell formulation, Gf is reflected in individual differ-
ences in intelligence-as-process, or general cognitive ability. In contrast, Gc is reflected
in individual differences in intelligence-as-knowledge, as acquired through experiential
and educational means. Although Ackerman’s theory is designed for broad applications
in educational and vocational contexts, the theory has implications for prediction of
job performance as well. Specifically, individual differences in intelligence-as-process
are proposed to exert a direct effect on performance (depending on the task) as well
as an indirect effect on performance through individual differences in the accumula-
tion of knowledge. Individual differences in intelligence-as-knowledge can be expected
to influence performance through the experiential and educational amassing of domain-
relevant knowledge (e.g., knowledge of computer technology should be a strong predictor
of performance for computer programmers and technicians). Consistent with Hunter’s
(1983) notion of an ability–knowledge–performance pathway, as well as empirical find-
ings obtained by Schmidt, Hunter and colleagues (Hunter, 1983; Schmidt et al., 1986;
Schmidt et al., 1988), Ackerman’s theory provides a broad theoretical foundation for
the observed findings, suggests that greater attention be paid to developing individual
difference measures of knowledge, and provides a potential integration of ability and
non-ability predictors of performance.
In summary, meta-analytic findings reported over the past two decades provide com-
pelling evidence for the predictive validity of general cognitive ability for job perfor-
mance, and the use of such measures in a wide range of selection contexts. Recent theory
and research has been directed toward understanding the sources of variability underly-
ing observed ability–performance relations. Consistent with findings by Ackerman and
others (e.g., Ackerman, 1988; Fleishman, 1972), the direct influence of general cognitive
ability on performance appears related to task demands. General ability–performance
relations tend to be highest in jobs and tasks that demand sustained attentional effort,
such as in skill acquisition or complex jobs such as air traffic control. In contrast, when
tasks can be highly proceduralized with practice, as is characteristic of less complex jobs
such as assembly work, general cognitive ability–performance proficiency relations may
be weaker, particularly among skilled employees.
In addition to direct influences of general cognitive ability on job performance, several
studies suggest that ability also influences job performance indirectly through its effects
on job knowledge, particularly in tasks that involve skilled performances. For example,
among assembly workers, individual differences in machine knowledge may exert a