British-born U.S. psychologist influential in establishing experimental and physiological psychology and author of An Introduction to Social Psychology (1908; 30th ed. 1960), which did much to stimulate widespread study of the basis of social behaviour.

Soon after becoming a fellow of St. John's College, Cambridge, McDougall joined the Cambridge Anthropological Expedition to the Torres Strait, between Australia and New Guinea, and there administered psychological tests to the native inhabitants. He then went to Germany, where, at the University of Göttingen, he conducted research on colour vision. His interest in psychical research also dates from that period. An assistant at the experimental laboratory, University College, London (1901), he was appointed reader in mental philosophy at the University of Oxford (1904), where he wrote Physiological Psychology (1905), demonstrating the value of a thoroughgoing biological approach in place of the traditional philosophical approach.

McDougall's well-known Introduction to Social Psychology developed a Darwinian theory of human behaviour based on the assumption of inherited instinct, or tendency, to note particular stimuli and to respond to them for the purpose of attaining some goal. Should response be delayed, an emotional reaction follows. Diversification and stabilization of response result from learning. A classic work, Body and Mind (1911), subtitled A History and Defense of Animism represented the kind of espousal of unpopular causes that increasingly tended to isolate McDougall from colleagues.

Opposed to mechanistic interpretations of human behaviour, he wrote The Group Mind (1920), a speculative attempt to interpret national life and character that was intended as a sequel to his Social Psychology. Its poor reception was partly responsible for his move that year to the United States and a professorship at Harvard University. Maintaining that the basic human activity is searching for goals, he generally alienated himself from the dominant U.S. behaviourists, who confined psychology to observable evidence of organismic activity. In an attempt to demonstrate inheritance of acquired characteristics, he published Outline of Psychology (1923) and Outline of Abnormal Psychology (1926). Finding his situation at Harvard unsatisfactory, in 1927 he moved to Duke University, Durham, N.C. There he developed a psychology department and continued various research, including work in parapsychology.

one of the fathers of Canadian Confederation who later served unsuccessfully as lieutenant governor of the Northwest Territories.

McDougall practiced law as a solicitor, being called to the bar in 1862. As one of the leaders of the “Clear Grit,” or radical wing of the Reform Party, he founded in 1850 the North American, a newspaper that expressed the radicals' political views. This paper was absorbed by The Globe (Toronto) in 1857, when McDougall became an associate of The Globe's publisher George Brown, the Liberal Party leader. The following year McDougall was elected to the legislature of the united province of Canada. He was appointed commissioner of crownlands in the John Sandfield Macdonald–Louis Victor Sicotte administration in 1862, and in 1864 he became provincial secretary.

McDougall attended the Charlottetown, P.E.I.; Quebec; and Westminster conferences leading to Confederation, which was achieved in 1867, when the British Parliament passed the British North America Act. As one of the leading liberals in the first Dominion government, McDougall was minister of public works in 1867–69, during which time he accompanied Sir George Étienne Cartier to England to arrange the acquisition of Hudson's Bay Company land for the Dominion of Canada. McDougall took up the post of lieutenant governor of Rupert's Land and the Northwest Territories in 1869, but his attempts to exert his authority met with resistance from the Red River settlers, who repelled him at Pembina.

McDougall was removed from office in 1869 and soon lost political influence. After retiring from public life, he resumed his legal practice in 1873.