A time and motion study would be used to reduce the number of motions in performing a task in order to increase productivity. The best known experiment involved bricklaying. Through carefully scrutinising a bricklayer's job, Frank Gilbreth reduced the number of motions in laying a brick from 18 to about 5. Hence the bricklayer both increased productivity and decreased fatigue.
The Gilbreths developed what they called therbligs ("therblig" being "Gilbreth" spelled backwards, with a slight variation), a classification scheme comprising 17 basic hand motions. 1920 Frank B. and Lillian Gilbreth develop their time and motion studies.