over the dangers of hypnosis caused him to discontinue his research. Behavior Clark 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. He also was impacted by Edward Thorndike, as he adapted his theory to include and agree with Thorndike's law of effect. After Hull discovered his interest in learning theories from Pavlov, Watson, and Thorndike, he dedicated much of his own laboratory work to perfecting his own theory. Also, many experiments concerning his learning theory came from Hull's students, who carried out many different experiments in Hull's lab after finding inspiration from seminars and lectures in classes that Hull taught. Quantification was a chief concern of Hull's studies, and he continued to apply this interest to behaviorism. While interested in the work of Watson, he was not entirely convinced. After listening to lectures by gestalt psychologist Kurt Koffka, he began to work towards a neobehaviorism. His goal was to determine the laws of behavior and how they can be used to determine future behaviors. His work with the computing machine led him to believe a machine could be built to replicate mental processes. In his book, Principles of Behavior, he developed the following formula: SER = SHR × D × V × K Where: SER is excitatory potential (likelihood that the organism would produce response r to stimulus s), SHR is the habit strength (derived from previous conditioning trials), D is drive strength (determined by, e.g., the hours of deprivation of food, water, etc.), V is stimulus intensity dynamism (some stimuli will have greater influences than others, such as the lighting of a situation), and K is incentive (how appealing the result of the action is). A variety of other factors were gradually added to the formula to account for results not included by this simple function. Eventually the formula became: SER = V x D x K x J x SHR - IR - SIR - SOR - SIR such that IR is reactive inhibition (inhibition caused by continual performance of a behavior that dissipates over time), SIR is conditioned inhibition (inhibition caused by continual performance of a behavior that does not dissipate over time). SLR is Reaction threshold, the smallest amount of reinforcement that will produce learning. Hull originally intended to make a trilogy of books on behavior, explaining social and cognitive behavior.