William E. Blatz

William Emet Blatz (1895 to 1964) was a German-Canadian developmental psychologist who directed the University of Toronto Institute of Child Study from 1925 until 1960. Born in Hamilton, Ontario, he took a medical degree at Toronto and a doctorate in psychology at the University of Chicago under Harvey A. Carr. He is best known for security theory, which holds that children first need complete trust in caregivers, called dependent security, and that this secure base gives them the courage to explore and eventually trust themselves, called independent security. Because of its similarity and because Blatz was Mary Ainsworth doctoral advisor, security theory is seen as a precursor to attachment theory. He rejected Freudian ideas about the unconscious, served as educational consultant to the Dionne quintuplets from 1935 to 1938, and helped set up a model nursery training centre in Birmingham, England, in 1942.