Alexander Thomas, 89; Psychiatrist Studied Human Temperament

Alexander Thomas, 89, a child psychiatrist who studied the human temperament, died Wednesday at a hospital in New York City. The cause of death was not announced.

Throughout his career, Thomas often collaborated with his wife, Stella Chess, who was also a child psychiatrist. In the late 1950s, they and other colleagues began the New York Longitudinal Study, which tracked the emotional and social development of 133 children, starting at birth, for 30 years.

The researchers found that temperament appears to be well established at birth but can change over time. So, though genes decide some aspects of a person’s personality, one’s environment may cause changes.

Thomas and Chess wrote numerous papers and books based on their research. “Origins and Evolution of Behavior Disorders” (1987), “Temperament in Clinical Practice” (1995), and “Temperament: Theory and Practice” (1996) are still in print.

Thomas graduated from City College of New York in 1932 and from New York University College of Medicine in 1936. He served as a captain and medical officer in the Army Air Forces during World War II.

From 1968 to 1978, Thomas was director of psychiatry at Bellevue Hospital in New York City. During his tenure, he co-wrote “Racism and Psychiatry” (1972), which explored the effect of white racist attitudes on the mental health field.