Leon Kamin

Leon J. Kamin (December 29, 1927 – December 22, 2017) 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".

Leon Kamin was born into a Jewish family in Taunton, Massachusetts; his father was a rabbi.Kamin studied psychology at Harvard. While a Harvard undergraduate, he was member of the Communist Party, but dropped out of the party by 1950. Later, while a graduate student, Kamin was subpoenaed by the McCarthy Committee, where he refused to name others who had been Communists. As a result, Kamin was convicted of contempt of the Senate during the McCarthy era 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. However, subsequent research suggests it is not as robust as previously thought.

In March 1972 an invitation from the Princeton Psychology Department (which Kamin chaired at the time) to Richard Herrnstein (who had a few months earlier published a contentious article about race, gender, class, and intelligence) sparked a major controversy and threats of protest.Herrnstein canceled his visit, saying that "It would be enough for me not to come if they had placards on the wall." Kamin defended the invitation to Herrnstein, opposed the protests, and organized a meeting to discuss the controversy.The resulting debates spurred Kamin to start investigating the work on heritability of intelligence of Cyril Burt, work that Herrnstein was citing to support his views.Kamin concluded that Burt had falsified his data; in 1974 he published his analysis in the book The Science and Politics of IQ.

Kamin 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.

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