Mary Salter Ainsworth (born December 1, 1913, Glendale, Ohio, United States—died March 21, 1999, Charlottesville, Virginia) was an American Canadian developmental psychologist known for her contributions to attachment theory.

When she was five years old, Mary Salter’s family moved to Toronto, where her father became president of a manufacturing firm. At age 15 she read Character and the Conduct of Life (1927), by the American psychologist William McDougall, which inspired her to study psychology. A year later she entered the University of Toronto, earning bachelor’s (1935), master’s (1936), and Ph.D. (1939) degrees.

After a stint as an instructor at the University of Toronto, she entered the Canadian Women’s Army Corps in 1942, gaining substantial clinical and diagnostic skills. She returned to the University of Toronto in 1946 and married Leonard Ainsworth, a World War II veteran and graduate student, in 1950.

Leonard’s decision to complete his doctoral studies in London led to Mary’s collaboration with the British psychologist John Bowlby at the Tavistock Institute for Human Relations, where she was exposed to Bowlby’s emerging ideas about the evolutionary foundation of infant-mother attachment. She also admired the naturalistic observations of mother-child separation conducted by Bowlby’s research assistant, James Robertson. In 1953, when Leonard accepted a postdoctoral position at the East African Institute for Social Research in Kampala, Uganda, Mary was able to undertake a short-term longitudinal study of mother-infant attachment interactions in Ganda villages. Her research was eventually published as a book, Infancy in Uganda: Infant Care and the Growth of Love (1967).

After the Ainsworths’ move to Baltimore, Maryland, in 1954, Mary performed diagnostic work at a psychiatric hospital and lectured at Johns Hopkins University, where she became associate professor of developmental psychology in 1958. Shortly thereafter, she and Leonard divorced.

Appointed to a full professorship in 1963, Mary Ainsworth launched the Baltimore Project, modeled on her work in Uganda. Monthly home visits to 26 families began after a child’s birth and ended at 12 months. Detailed narratives captured the quality of interactions between mother and infant during feeding, contact, play, and distress episodes. The final observation, at 12 months, consisted of a mother-infant separation and reunion procedure now known as the Strange Situation (see attachment theory: Individual-difference features of attachment theory). Patterns of infant behaviour during this laboratory procedure were predicted by maternal sensitivity and harmonious interaction qualities at home. Her findings, published during the next decade in several journal articles and a book, Patterns of Attachment (1978), inspired major longitudinal attachment studies in the United States, West Germany, and Israel.

In 1975 she joined the faculty of the University of Virginia, becoming Commonwealth Professor of Psychology in 1976. She retired as professor emeritus in 1984. Among her many honours was the American Psychological Association’s Gold Medal Award for Life Achievement in the Science of Psychology in 1998.

Are you a student?

Get a special academic rate on Britannica Premium.

Subscribe