Branch of psychology concerned with solving practical problems of human behaviour by using the findings and methods of psychological science. Intelligence testing, legal problems, industrial efficiency, motivation, and delinquency were among the first areas of application in the early 20th century. World Wars I and II fostered work on vocational testing, teaching methods, evaluation of attitudes and morale, performance under stress, propaganda and psychological warfare, and rehabilitation. The aviation and aerospace industries were important for the development of engineering psychology, the study of human-machine relationships. Other areas include consumer psychology, school psychology, and community psychology. See also industrial-organizational psychology; psychometrics