On May 24, 1884, American psychiatrist Clark Leonard Hull was born. Hull sought to explain learning and motivation by scientific laws of behavior and is also known for his work in drive theory. He was able to establish his analysis of animal learning and conditioning as the dominant learning theory of its time. He is perhaps best known for the “goal gradient” effect or hypothesis, wherein organisms spend disproportionate amounts of effort in the final stages of attainment of the object of drives.
Clark Leonard Hull grew up on a farm in Michigan, where he and his brother Wayne helped by performing manual labor and chores around the house. He was educated in a small village school, but probably often missed school due to farm work. Hull became a teacher in a similar school when he was only 17 and attended a high school in west Saginaw County. At Alma Academy, Hull continued his education and became most enthusiastic about mathematics, and especially geometry. In that period, Clark Hull probably first read the works of philosopher Baruch Spinoza, who he admired but also disagreed with. After catching typhoid, Hull was left with permanent amnesia and a general bad memory for names which affected him throughout the rest of his life. His education continued in the field of math, physics, and chemistry.
Later on, Hull’s enthusiasm for philosophy led to his interest the psychology, which he continued to study. Especially, William James’ book Principles of Psychology influenced him in the beginning. He attended the University of Michigan to study psychology and received his bachelor’s degree in 1913. he started teaching, for instance psychological testing and measurement courses. Clark Hull also became interested in suggestion and hypnosis and wrote his first book on the matter titled Hypnosis and Suggestibility in 1933. Hull became professor of psychology at Yale University and researched in the field of behavior theory.
In the field of behavior theory, Clark Hull was highly influenced by Ivan Pavlov and Watson, as well as Edward Thorndike. Hull proceeded to dedicate much of his laboratory work to develop his own theory. Hull also discussed many of his ideas with the students in his courses. Hull began to work towards neobehaviorism with the goal to determine the laws of behavior and how they can be used to determine future behaviors. He developed formulas and worked with the computing machine as he believed a machine could be built to replicate mental processes.
Clark Hull put the emphasis of his work on experimentation, an organized theory of learning, and the nature of habits, which he argued were associations between a stimulus and a response. Behaviors were influenced by goals that sought to satisfy primary drives—such as hunger, thirst, sex, and the avoidance of pain. His systematic behavior theory, also known as drive theory, is that of a reinforcement system, which means that in learning, habits are initially formed by reinforcing certain behaviors. Reinforcement of a response to a behavior supplies an effect that satisfies a need. In other words, this satisfaction of needs helps create habits out of behaviors. Specifically, Hull’s theory posits that behaviors that satisfy needs, later described by Hull as cravings rather than needs, reduce these cravings. He called this concept drive-reduction, or drive-stimulus reduction. Other behaviorists found Hull’s theories to be too cumbersome for practical use, leading to his work to be eclipsed by Skinner.
At yovisto academic video search you can learn more about motivation from a social scientific perspective in a lecture titled The Surprising Science of Motivation by Dan Pink.
References and Further Reading:
-  Clark Leonard Hull at Psychology History
-  The Conflicting Psychologies of Learning: A Way Out, Clark L. Hull (1935), Psychological Review, 42, 491-516
-  National Academy of Sciene Memoirs
-  Pavlov and the Conditional Reflex, SciHi Blog
-  Edward Thorndike and the Law of Effect, SciHi Blog
-  Clark Leonard Hull at Wikidata