(July 24, 1942 – )
American Psychologist



  • Boston University, B.A. in psychology (1967)
  • University of Alabama, Ph.D. in psychology (1970)
  • Northwestern University, postdoctoral studies with Benton J. Underwood (1972-1973)


  • University of Alabama, Research Assistant to Dr. Norman Ellis (1967-1970)
  • University of Dayton, Assistant Professor of Psychology, 1970-1972
  • Case Western Reserve University, Assistant Professor of Psychology (1973-1975); Associate Professor (1976-1978);  Associate Professor with Tenure (1979-1983); Chair, Department of Psychology (1982-1985); Professor of Psychology (1983-present)
  • Visiting Scientist, IPA program, Air Force Human Resources Laboratory, Test and Training Research (MOE), Brooks Air Force Base, Texas (1985-1986)
  • Case Western Reserve University, Louis D. Beaumont University Professor (1998 – present); Chair, Department of Psychology (2003 – present)
  • Editor and reviewer for several journals
  • Founding Editor of Intelligence: A Multidisciplinary Journal (1977)
  • Founded the International Society for Intelligence Research (ISIR) (2000)
  • Numerous awards, including: Fellow, American Psychological Association (1978-1998); Fellow, American Psychological Society, Charter Member (1990-1998); Mensa Research Award (1991)

Definition of Intelligence

“Intelligence is not an easy thing to define, and in fact it’s even more difficult because any words associated with intellectual ability or intelligence become corrupted with common use. Words like moron, idiot and imbecile all started off as scientific terms, but they’ve been corrupted by common use …So I think a better approach is to define things like general intelligence, or g, where we have a mathematical definition, and where we can attempt to get a scientific explanation of the construct… That is, we can define g—general intelligence—in terms of correlations among mental tests, and then attempt to explain that g using theory and empirical tests…I think we are much better off to focus on the things we can explicitly define in a scientific way, and attempt to understand those.  That’s essentially what I’ve done, is to try to understand g, which I think is a major component of mental ability (personal communication, August 23, 2002).”

Major Contributions

Click here to see the interview transcript and video clips

Ideas & Interests

The focus of Douglas K. Detterman’s prolific research career can be summed up in one question:  Why are some people smarter than others? This question, listed alone on his curriculum vitae under “research interests” provides the overarching theme for decades of research into mental retardation, memory and intelligence theory.

An articulate and influential supporter of Spearman’s theory of general intelligence, Dr. Detterman’s research has contributed a great deal to our understanding of g.  One significant finding is that g becomes increasingly dominant at the lower extreme of the IQ continuum; that is, correlations among scores on cognitive tests are the highest in individuals with the lowest IQs. This suggests that people with mental retardation have a deficit in something that powers all areas of cognition, rather than discrete deficits in specific information-processing capabilities (Detterman & Daniel, 1989).  Detterman has dubbed this the “everything deficit” (personal communication, August 23, 2002). g is less obvious in individuals with average and high IQs, as they tend to show a less even distribution of mental abilities.

Another of Dr. Detterman’s important contributions to the field of intelligence theory has been his role as leader and initiator.  In 1977 he founded Intelligence:  A Multidisciplinary Journal, a peer-reviewed publication devoted to high-quality research on human cognitive ability.  He still serves as editor. In 2000 founded the International Society for Intelligence Research (ISIR), a scientific society for researchers interested in human intelligence.  These venues provide forums for intelligence researchers to gather and communicate.  In addition, Dr. Detterman has served as editor for several books that bring together diverse perspectives on intelligence theory and psychometrics (Detterman, 1985; 1993a; 1993b; Detterman & Sternberg, 1982; Sternberg & Detterman, 1979; 1986).  These efforts, combined with his personal vision for the future of intelligence research (Detterman, 1979; 1989) are helping the field to maintain momentum and direction.

Selected Publications

Detterman, D. K. (1982). Does “g” exist? Intelligence, 6, 99-108.

Detterman, D. K. (1987). Theoretical notions of intelligence and mental retardation. American Journal of Mental Deficiency , 92, 2-11.

Detterman, D. K. (1994). A system theory of intelligence . In D.K. Detterman (Ed.). Current topics in human intelligence: Vol. 4. Theories of Intelligence (pp. 85-115) . Norwood , NJ : Ablex Publishing Corporation.

Detterman,  D. K. (1999). The psychology of mental retardation. International Review of Psychiatry, 11, 26-33.

Detterman, D. K. & Daniel, M. H. (1989).  Correlations of mental tests with each other and with cognitive variables are highest for low-IQ groups.  Intelligence 13, 349-359.

Detterman, D. K., & Thompson, L. A. (1997). IQ, schooling, and developmental disabilities: What’s so special about special education? American Psychologist, 52, 1082-1091.

Frey, M. C. & Detterman, D. K. (2004). Scholastic assessment or g? The relationship between the SAT and general cognitive ability. Psychological Science, 15(6), 373-398.


Detterman, D. K. (1979).  A job half done: Human intelligence research in the year 2000.  Intelligence, 3, 295-306.

Detterman, D. K. (Ed.).  (1985). Current topics in human intelligence:  Vol. 1, Research Methodology.  Norwood, NJ:  Ablex.

Detterman, D. K. (1989).  The future of intelligence research.  Intelligence, 13, 199-203.

Detterman, D. K. (Ed.). (1993a). Current topics in human intelligence: Vol. 2. Is the mind modular or unitary?  Norwood, NJ:  Ablex.

Detterman, D. K. (Ed.). (1993b). Current topics in human intelligence: Vol. 3. Individual differences in cognition. Norwood, NJ:  Ablex.

Detterman, D. K. & Daniel, M. H. (1989).  Correlations of mental tests with each other and with cognitive variables are highest for low-IQ groups.  Intelligence 13, 349-359.

Sternberg, R. J., & Detterman, D. K. (Eds.). (1979). Human intelligence:  Perspectives on its theory and measurement. Norwood, NJ:  Ablex.

Detterman, D. K., & Sternberg, R. J. (Eds.).  (1982). How and how much can intelligence be increased?  Norwood, NJ:  Ablex.

Sternberg, R. J., & Detterman, D. K. (Eds.). (1986). What is intelligence?  Contemporary viewpoints on its nature and definition.  Norwood, NJ:  Ablex.

Photo Courtesy of Douglas K. Detterman

Douglas K. Detterman Page at Case Western Reserve University

International Society for Intelligence Research (ISIR)