Leon Kamin

Who is Leon Kamin?

Leon J. Kamin is 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 discovered several important facts about conditioning, including the "Kamin Effect" and the "blocking effect". Kamin was blacklisted during the McCarthy era and had to find employment in Canada, where he chaired the Psychology Department at McMaster University in Ontario, Canada. When he was removed from the blacklist in 1968, he returned to the US and chaired Princeton University's Department of Psychology and later the Psychology Department at Northeastern University in Boston, MA.

Kamin's most well-known contribution to learning theory was his discovery and analysis of the "blocking effect". He showed that conditioning an animal to associate a salient conditioned stimulus, such as a bright light, with a salient unconditioned stimulus, like a shock, is "blocked" when CSb is presented simultaneously with another conditioned stimulus that was already conditioned to the US.. The blocking effect is one of the hallmark effects in the study of associative learning in animals, including humans.