John Broadus Watson

John Broadus Watson (January 9, 1878 – September 25, 1958) was an American psychologist who established the psychological school of behaviorism. Watson promoted a change in psychology through his address Psychology as the Behaviorist Views it, which was given at Columbia University in 1913. Through his behaviorist approach, Watson conducted research on animal behavior, child rearing, and advertising. In addition, he conducted the controversial "Little Albert" experiment and the Kerplunk experiment. Watson popularized the use of the scientific theory with behaviorism. He was also editor of Psychological Review from 1910 to 1915. A Review of General Psychology survey, published in 2002, ranked Watson as the 17th most cited psychologist of the 20th century.

Main contributions：
①"Twelve infants" quotation
The quotation often appears without context and with the last sentence omitted, making Watson's position appear more radical than it actually was. In Watson's book Behaviorism, the sentence is provided in the context of an extended argument against eugenics. That Watson did not hold a radical environmentalist position may be seen in his earlier writing in which his "starting point" for a science of behavior was "...the observable fact that organisms, man and animal alike, do adjust themselves to their environment by means of hereditary and habit equipments."  Nevertheless, Watson recognized the importance of nurture in the nature versus nurture discussion which was often neglected by his eugenic contemporaries.

②Limitations of the conditioning paradigm
The conditioning paradigm has certain limitations. Researchers have had a hard time conditioning infants that are just a few months old. This might be because they have not yet developed what Piaget calls "primary circular reactions". Because they cannot coordinate sensory motor actions they cannot learn to make different associations between their motoric behaviors and the environment. Another limitation concerns the kind of conditioned stimuli humans can learn. When researchers attempt to condition children to fear things such as curtains or wooden blocks they have had great difficulty. Humans may be "innately disposed to fear certain stimuli".

Selected works byJohn Broadus Watson：
Watson, John B. (1908). "The Behavior of Noddy and Sooty Terns." "Carnegie Institute Publication," 103, 197-255.
Watson, John B. Behavior: An introduction to comparative psychology. Henry Holt, 1914
Watson, John B (1915). "Recent experiments with homing birds". Harper's Magazine. 131: 457–64.
Watson, John B. Behaviorism (revised edition). University of Chicago Press, 1930.
Watson, John B. "John Broadus Watson [Autobiography]." In C. Murchison (Ed.), A History of Psychology in Autobiography (Vol. 3, pp. 271–81). Clark University Press, 1936.

Reference
https://en.wikipedia.org/wiki/John_Broadus_Watson