Lillian was one of the pioneers of what is now known as human factors engineering and ergonomic design, among her other accomplishments. Via Wikipedia
Lillian Evelyn Moller Gilbreth was an American psychologist and industrial engineer. She was described in the 1940s as “a genius in the art of living.” One of the first working female engineers holding a Ph.D., she is held to be the first true industrial/organizational psychologist. She and her husband Frank Bunker Gilbreth, Sr. were efficiency experts who contributed to the study of industrial engineering in fields such as motion study and human factors. The books Cheaper by the Dozen and Belles on Their Toes (written by their children Ernestine and Frank Jr.) tell the story of their family life with their twelve children, and describe how they applied their interest in time and motion study to the organization and daily activities of such a large family. Both books were later made into feature films.