Influenced by his undergraduate training in science, he applied mathematical techniques to the study of psychology, making the discipline more objective and quantitative.
Cattell became one of the world's leading personality theorists, and developed many widely used psychological tests, of which the best known is the 16 Personality Factor (16PF) personality assessment.
The reward, such as pellets of food or water, acts as a primary reinforcer.
He observed the behaviour of animals adapted to utilize the opportunity for a reward.
He pioneered study of the magnetic orientation of minerals in rocks to reveal the Earth's history of its magnetic field.
The last fifty years of his life were to a large part given to studies relevant to biology: a theory of organisms.
He proposed that this magnetic field resulted from electric currents induced in the fluid outer core of the Earth.The 1907 paper he wrote analyzing the law of causality caught Einstein's attention, who in 1912 recommended Frank as his successor as professor of theoretical physics at the German University of Prague.He held that position until 1938, when he moved to Harvard University in the U.His later research on fish farming expanded to include mollusk aquaculture and he directed a program to develop quantitative methods to aid in the management of fisheries resources.« .American biologist who went on expeditions in Panama, British Guiana, Brazil, and Venezuela (1937-39).