Clark Leonard Hull (May 24, 1884 – May 10, 1952) was an influential American psychologist who sought to explain learning and motivation by scientific laws of behavior.Hull is known for his debates with Edward C. Tolman.He is also known for his work in drive theory.Hull spent the mature part of his career at Yale University, where he was recruited by the president and former-psychologist, James Rowland Angell.lark Hull found inspiration for his own theory of learning after learning about Ivan Pavlov ’s idea of conditional reflexes, and Watson ’s system of behaviorism.