Clark Leonard Hull was an 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.

Edward Chace Tolman was an American psychologist and a professor of psychology at the University of California, Berkeley. Through Tolman's theories and works, he founded what is now a branch of psychology known as purposive behaviorism. Tolman also promoted the concept known as latent learning first coined by Blodgett (1929). A Review of General Psychology survey, published in 2002, ranked Tolman as the 45th most cited psychologist of the 20th century.