American psychologist whose work at Vassar College in Poughkeepsie made it a leading institution in undergraduate psychological research and education.

Washburn graduated from Vassar College in 1891. She then studied briefly at Columbia University, New York City, where she was allowed to audit courses and work in James M. Cattell (Cattell, James McKeen)'s new laboratory of experimental psychology but was not admitted as a regular student. In 1892 she entered Cornell University, Ithaca, New York, where she studied under Edward Bradford Titchener (Titchener, Edward Bradford), and she received a Ph.D. in psychology in 1894. For six years she was professor of psychology, philosophy, and ethics at Wells College, Aurora, New York. She returned to Cornell (1900–02) as warden of Sage College, a women's residence; during that time she also taught courses in animal and social psychology.

After a year of teaching at the University of Cincinnati, Ohio, Washburn returned to Vassar to teach psychology. She remained (from 1908 as full professor) until her retirement in 1937. A remarkably effective teacher, she made Vassar a leading centre of undergraduate training and research in psychology. The results of her joint researches with advanced students were reported in a series of Studies from the Psychological Laboratory of Vassar College. Her own publications include scores of articles, reviews, and notes in professional journals and two books, The Animal Mind (1908) and Movement and Mental Imagery (1916). The former is a summary of studies that is of lasting importance, and the latter is a development of Washburn's dualistic motor theory of mental activity, an attempt to find a compromise between the opposed and equally one-sided schools of behaviourism and introspection.

Washburn served as a cooperating editor of the American Journal of Psychology (1903–25) and as one of its four coeditors from 1925; she was also associated with the Psychological Bulletin, the Psychological Review, the Journal of Comparative Psychology, and the Journal of American Behavior. In 1927 a special number of the American Journal of Psychology honoured Washburn. She was a member of the National Research Council (1919–20, 1925–28), and in 1931 she became the second woman (after Florence R. Sabin (Sabin, Florence Rena)) to be elected to the National Academy of Sciences.