Nancy Bayley (1899-1994)

Nancy Bayley, an eminent developmental psychologist, made significant contributions to the measurement of infant intelligence and human development. Born in Dalles, Oregon, on September 28, 1899, she is best known for her work leading to the publication of the Bayley Scales of Infant Development in 1968 and the revised edition in 1993. Her career, spanning six decades, may have been influenced by her work on the world-renowned Berkeley Growth Study, a longitudinal study she initiated in 1928 that followed subjects from infancy through adulthood. Her productive career produced more than 200 publications about child development and she received many awards. Bayley was the first woman to receive the Distinguished Scientific Contribution Award of the American Psychological Association in 1966. Other awards included the Gold Medal Award of the American Psychological Association in 1982 and the G. Stanley Hall Award for distinguished contributions to developmental psychology in 1971.

Prior to taking an introductory psychology course with Edwin R. Guthrie, Bayley planned to teach English. With her interest in psychology sparked, Bayley earned her master's degree from the University of Washington just two years after earning her bachelor's degree at the same institution. She earned her Ph.D. at the University of Iowa in 1926.

Bayley was descended from pioneering ancestors including paternal grandparents who sailed around Cape Horn to Victoria, British Columbia, and maternal grandparents who traveled west by covered wagon. Like her ancestors, Bayley has been described as a pioneer who extended the study of human development to a lifespan perspective and meticulously studied a wide range of interests. She demonstrated her adventuresome spirit when she carried out a series of studies measuring fear reactions on a galvanometer. According to a 1930 news account, she shot off a .38 revolver in class to elicit and measure fear response. Most of her studies were concerned with detailed exploration of physical and mental growth and intelligence predictability. She explored relationships among measured characteristics and carefully considered environmental and other influences on her subjects. Bayley's interests included the study of physical maturation, body build, androgyny, and sex differences. By 1962, through her studies of skeletal maturation, she developed a means of predicting adult height within one inch. The tables she developed are still used by endocrinologists.

Bayley's career focused on developing tests for infants and young children that correlate with other measures and/or predict later intelligence. While looking for data trends and groupings, she highlighted individual differences in human development. She did not believe intelligence was fixed and studied the cause of variability in scores across the lifespan. She was ahead of her time when she examined changes in intelligence in adulthood in the 1950s. She was one of the first to consider the impact of child-rearing attitudes and behaviors on child development, and recognized that there are so many factors influencing development that it would be difficult to isolate any one factor, genetic or environmental, as possessing the greatest importance.

Bayley was an outstanding developmental psychologist distinguished by her contributions and her early anticipation of current topics. Although she spent most of her professional life at the University of California, Berkeley, she also spent ten years at the National Institute of Mental Health in Maryland beginning in 1954 as chief of the Section on Early Development, Laboratory of Psychology. Bayley was a leader in her field who left a legacy of work and contributions worthy of further study.