of tasks (such as math or writing) can be expected to result in an increase in
interest to perform such tasks in the future. If the interests are followed-
through, domain knowledge will increase in that area, which in turn will both
result in an increment in self-concept and interests, in a virtuous circle. In
contrast, early failures at a task may be expected to decrement interests, and
thus result in both lower self-concept and avoidance of future opportunities
to acquire domain knowledge—a vicious circle. Although these hypotheses
have intuitive appeal, experimental confirmation awaits the expense and time
necessary to construct and evaluate longitudinal studies. We have found the
nomothetic approach to determining development and change to be a quite
useful one. On the one hand, it is important to note that although this ap-
proach captures a substantial portion of the variance in behavioral predic-
tion, individual lives are undoubtedly more complicated than can be captured
from such a perspective. On the other hand, the trait complex perspective al-
lows for a profile approach to describing individuals. An adequate profile
might include an array of trait complex scores, traditional ability measures,
and measures of the breadth and depth of knowledge. While this does not
quite reach an ideographic level of description for an individual, it goes far
beyond traditional approaches, and it allows for an integration that usually
requires a trained psychometrist to qualitatively assemble different, but re-
lated, domains of assessments to provide vocational or academic advice.
REFERENCES
Ackerman, P. L. (1984). Multivariate evaluation of workload, resources, and performance in
dual task data.Proceedings of the 28th annual meeting of the Human Factors Society, 28,
210–214.
Ackerman, P. L. (1994). Intelligence, attention, and learning: Maximal and typical performance.
In D. K. Detterman (Ed.),Current topics in human intelligence: Theories of intelligence(Vol.
4, pp. 1–27). Norwood, NJ: Ablex.
Ackerman, P. L. (1996). A theory of adult intellectual development: Process, personality, inter-
ests, and knowledge.Intelligence, 22, 229–259.
Ackerman, P. L. (2000). Domain-specific knowledge as the “dark matter” of adult intelligence:
Gf/gc, personality and interest correlates.Journal of Gerontology: Psychological Sciences,
55B(2), P69–P84.
Ackerman, P. L. (2002). Gender differences in intelligence and knowledge: How should we look
at achievement score differences?Issues in Education: Contributions from Educational Psy-
chology, 8(1), 21–29.
Ackerman, P. L., Bowen, K. R., Beier, M. B., & Kanfer, R. (2001). Determinants of individual
differences and gender differences in knowledge.Journal of Educational Psychology, 93,
797–825.
Ackerman, P. L., & Heggestad, E. D. (1997). Intelligence, personality, and interests: Evidence
for overlapping traits.Psychological Bulletin, 121,219–245.
Ackerman, P. L., & Rolfhus, E. L. (1999). The locus of adult intelligence: Knowledge, abilities,
and non-ability traits.Psychology and Aging, 14, 314–330.
Anastasi, A. (1982).Psychological testing(5th ed.). New York: Macmillan.
138 ACKERMAN AND KANFER