(September 7, 1928 – August 18, 2006)

American Psychologist

Influences

Education

  • University of Denver, B.A. (triple major) in psychology, mathematics and chemistry (1956)
  • University of Melbourne, Australia, Fulbright Scholar, specialty areas: Clinical psychology and personality (1956-1957).
  • University of Illinois, Urbana, M.A.(1960); Ph.D. in measurement and personality (1965)
  • University of Wisconsin, Madison, specialty area: Experimental design and analysis (1965)

Career

  • University of Denver, Department of Psychology, Assistant Professor (1961-1965); Associate Professor (1965-1969); Professor (1970-1986)
  • Lecturer, Educational Psychology, University of California at Berkeley (1967)
  • Research Associate, Institute of Psychiatry, University of London, England (1972)
  • Research Associate, Psychiatric Clinic, University Hospital, Lund, Sweden (1982)
  • Professor of Psychology & Head, Adult Development and Aging, University of Southern California (1986 – 2006)
  • Numerous awards, including: Research Career Development Award, National Institutes of Health (1968-1972); Annual Prize for Distinguished Publications in Multivariate Psychology (SMEP) (1972); Lifetime Achievement Award, SMEP (1992)

Definition of Intelligence

“…[I]ntellectual abilities are organized at a general level into two general intelligences, viz., fluid intelligence and crystallized intelligence and in terms of visual, auditory, memory and speed-of-thinking kinds of intelligence. …there are those influences which directly affect the physiological structure upon which intellectual processes must be constructed–influences operating through the agencies of heredity and injury: in adulthood development these are most accurately reflected in measures of fluid intelligence. In early (at birth, infancy and childhood) these influences affect both fluid and crystallized abilities. And on the other hand there are those influences which affect physiological structure only indirectly through agencies of learnings and acculturations: crystallized intelligence is the most direct resultant of individual differences in these influences” (Horn & Cattell, 1967)”.

Major Contributions

  • Theory of Fluid and Crystallized Intelligence ( Gf-Gc Theory)

Click here to see the interview transcript and video clips (forthcoming).

 Interview with Dr. Horn (with video clips)

Click here to see the interview transcript and video clips.

Ideas & Interests

John L. Horn began college with the goal of becoming a high school mathematics and chemistry teacher. His first love was psychology, however, which he construed as the study of the personalities of people. An elective course in abnormal psychology and a professor advising him during his third year led him to realize that he might go to graduate school and be able to study psychology full-time– an idea that was completely new and surprising: he switched his major to psychology. He won a Fulbright Fellowship which enabled him to study with Samuel Hammond at the University of Melbourne in Australia.  Hammond very much influenced his interest in personality theory: he read Piaget, Cattell and did hands-on work in a psychiatric hospital during his almost two years in Australia.  He entered gradate school at the University of Illinois, and began studying with the already prominent psychologist Raymond B. Cattell ; this was the beginning of an enduring partnership that would lead to significant advances toward understanding the nature of intelligence and the course of intellectual development across the human lifespan.

Horn believes that the weight of the evidence argues against a general factor ( g ) being responsible for all intelligent behavior. The Cattell-Horn theory of fluid and crystallized intelligence R. B. Cattell, 1941, 1950; 1971 (This book was dedicated to Horn); Horn, 1965; Horn & Cattell, 1966a, 1966b) proposes that general intelligence is actually a conglomeration of perhaps 100 abilities working together in various and different ways in different people to bring out different intelligences.  Gf-Gc theory separates these abilities broadly into, first, two different sets of abilities that have quite different trajectories over the course of development from childhood through adulthood.

Fluid abilities ( Gf ) drive the individual’s ability to think and act quickly, solve novel problems, and encode short-term memories. They have been described as the source of intelligence that an individual uses when he or she doesn’t already know what to do. Fluid intelligence is grounded in physiological efficiency, and is thus relatively independent of education and acculturation (Horn, 1967). The other factor, encompassing crystallized abilities ( Gc ), stems from learning and acculturation, and is reflected in tests of knowledge, general information, use of language (vocabulary) and a wide variety of acquired skills (Horn & Cattell, 1967). Personality factors, motivation and educational and cultural opportunity are central to its development, and it is only indirectly dependent on the physiological influences that mainly affect fluid abilities.

Many studies have demonstrated that fluid intelligence peaks in early adulthood and then declines, gradually at first and then more rapidly as old age sets in after about 70. Crystallized abilities continue to improve as individuals age (Horn & Cattell, 1967).

Horn’s most recent work, done primarily with Hiromi Masanga, suggests that in adulthood people funnel their abilities into areas of expertise. This takes away use and therefore retention of fluid abilities, but creates in the areas of expertise a kind of wide-span memory that enables the person to bring large amounts of information into immediate memory and use.  Ericsson & Kintsch (1995) first noticed this, but Masanaga and Horn have made it part of extended Gf-Gc theory. Also important is adult expertise reasoning. This depends on the wide-span memory. It enables experts, such as adults in major positions of responsibility in our culture, to reason at a higher level than people who depend primarily on fluid reasoning. This part of the theory thus is most important for understanding why so much of our culture –our technology as well as our business and political practices—is in the hands of adults aged well over age 40 and up into the 60’s and 70’s.

Selected Publications

Horn, J.L. (1965). Fluid and crystallized intelligence: A factor analytic study of the structure among primary mental abilities. Ph.D. Thesis. University of Illinois.

Horn, J. L., & Cattell, R. B. (1966a). Refinement and test of the theory of fluid and crystallized general intelligences. Journal of Educational Psychology, 57, 253-270.

Horn, J. L., & Cattell, R. B. (1967). Age differences in fluid and crystallized intelligence. Acta Psychologica, 26, 107-129.

References

Cattell, R.B. (1941). Some theoretical issues in adult intelligence testng. Psychological Bulletin, 38, 592.

Cattell, R. B. (1950). Personality. New York: McGraw-Hill.

Cattell,R.B.(1971). Abilities: Their structure, growth and action. Boston: Houghton-Mifflin.

Ericsson, K.A. & Kintsch, W. (1995). Long-term working memory. Psychological Review, 105, 211-245.

Horn, J.L. (1965). Fluid and crystallized intelligence: A factor analytic study of the structure among primary mental abilities. Ph.D. Thesis. University of Illinois.

Horn, J. L. (1967). Intelligence: Why it grows, why it declines. Transaction, 23-31.

Horn, J. L., & Cattell, R. B. (1966a). Refinement and test of the theory of fluid and crystallized general intelligences. Journal of Educational Psychology, 57, 253-270.

Horn, J. L., & Cattell, R. B. (1966b). Age differences in primary mental ability factors. Journal of Gerontology, 21, 210-220.

Horn, J. L., & Cattell, R. B. (1967). Age differences in fluid and crystallized intelligence. Acta Psychologica, 26, 107-129.