1. Mental science applied to certain problems found in industry; dealing primarily with personnel selection, training, and the mental health of workers.
2. The branch of human behavior that is concerned with the efficient management of an industrial labor force and especially with problems encountered by workers in a mechanized environment: "Industrial psychology came into existence in the late 19th and early 20th centuries, at a time when industrial production was expanding, new types of labor and common occupations were emerging, and greater demands were being made on individuals."