Leon Kamin

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Leon Kamin
Born Leon Judah Kamin
(1927-12-29)December 29, 1927
Taunton, Massachusetts, United States
Died December 22, 2017(2017-12-22) (aged 89)
Nationality American
Education Harvard University
Known for Blocking effect
Learning theory
Race and intelligence
Spouse(s) Marie-Claire Kamin
Children 4
Scientific career
Fields Psychology
Institutions McGill University
Queen's University
McMaster University
Princeton University
Northeastern University
Thesis The effects of the interval between signal and shock on avoidance learning (1954)
Academic advisors Richard Solomon

Leon J. Kamin (December 29, 1927 – December 22, 2017)[1] was an American psychologist known for his contributions to learning theory and his critique of estimates of the heritability of IQ. He studied under Richard Solomon at Harvard and contributed several important ideas about conditioning, including the "blocking effect".

Early life and education[edit]

Born in Taunton, Massachusetts, Kamin studied psychology at Harvard. While a Harvard undergraduate, he had been a member of the Communist Party, but he had dropped out of the party by 1950. Later, while a graduate student, Kamin was subpoenaed by the McCarthy Committee, where he refused to name names. As a result, Kamin was convicted of contempt of the Senate during the McCarthy era[2] and had to find employment in Canada, where he chaired the Psychology Department at McMaster University in Hamilton, Canada (1957–58). In 1968 he returned to the U.S. and chaired Princeton University's Department of Psychology and later the Psychology Department at Northeastern University in Boston, Massachusetts.


Kamin's most well-known contribution to learning theory was his discovery and analysis of the "blocking effect" (1969). He showed that conditioning an animal to associate a salient conditioned stimulus (CSb), such as a bright light, with a salient unconditioned stimulus (US), like a shock, is "blocked" when CSb is presented simultaneously with another conditioned stimulus (CSa) that was already conditioned to the US. (Kamin used rats in most of his research, but the effect has been found in many animals). The blocking effect is one of the hallmark effects in the study of associative learning in animals, including humans.[according to whom?] However, subsequent research suggests it is not as robust as previously thought.[3]

Kamin long opposed the idea that significant personal traits are largely heritable. He became skeptical of the claims of Cyril Burt regarding the heritability of IQ, investigated Burt's work, and in 1974 published the book, The Science and Politics of IQ. He co-authored the controversial book Not in Our Genes (1984) with geneticist Richard Lewontin and neurobiologist Steven Rose. This book criticized sociobiology and evolutionary psychology. Kamin was known in some circles for his speculation that the heritability of IQ could be "zero". (Mackintosh, 1998) In 1983, he was named a Guggenheim Fellow in psychology.[4]

He was honorary professor of psychology at the University of Cape Town in South Africa.


In Race Differences in Intelligence (1974), Loehlin, Lindzey & Spuhler wrote (p. 85):

Kamin's more radical assertion of zero heritability, if substantiated, might not render the present book entirely meaningless, but it would certainly require a considerable revision of its language and point of view. In Appendix H we have taken a second look in the light of Kamin's critique at some of the data that provide the main focus for his misgivings, namely the studies of adoptive families and separated identical twins. We do not find these data to be quite as fragile as does Kamin, and we find Kamin's analysis to suffer from a number of statistical and logical problems.



  1. ^ In Memoriam: Dr. Leon J. Kamin (1927-2017)
  2. ^ (Kamin, 2005)
  3. ^ Maes E., Boddez Y., Alfei Palloni J., Krypotos A., D'Hooge R., De Houwer J., Beckers T. 2016. The elusive nature of the blocking effect: 15 failures to replicate. Journal of Experimental Psychology. General. (in press)
  4. ^ "Leon J. Kamin". John Simon Guggenheim Foundation. Retrieved 2018-07-23. 


  • Kamin, L. J. (1969). Predictability, surprise, attention, and conditioning. In B. A. Campbell & R. M . Church (Eds.), Punishment and aversive behavior (pp. 279–296). New York: Appleton-Century-Crofts.
  • Kamin, L.J. (2005). Letter to the Editor, New York Review of Books, May 26.
  • Mackintosh, N. (1998). IQ and Human Intelligence. Oxford: University Press. pp. 78–79.
  • Loehlin, Lindzey & Spuhler (Freeman, 1975). Race Differences in Intelligence (ISBN 0-7167-0754-3)

External links[edit]