as a dispositional trait, or “drive”, which is the component of Hull's motivational theory. She predicted that people with higher anxiety levels would show higher levels of eyelid conditioning than those with lower levels of anxiety. Spence then developed her own instrument to measure her hypothesis, the Taylor Manifest Anxiety Scale. Her later research focused primarily on elaborating Hull's drive theory. Awards and recognition Hull has been honored by a number of scientific societies. Hull was president of the American Psychological Association from 1935 to 1936. Hull was elected into the American Academy of Arts and Sciences in 1935 and also to the National Academy of Arts and Sciences in 1936. Hull received the Warren Medal during 1945 from the Society of Experimental Psychologists. Legacy Hull's ideas were so appealing in part because of his professional background in engineering. He was very good with math and numbers, and incorporated his numerical knowledge into the field of psychology. He followed the acceptable understanding of psychology at that time, and was influenced by the work and the conclusions of the pioneers of Behaviorism (Edward Thorndike, John B. Watson, and Ivan Pavlov). However, Hull was able to add his own twist to understanding reinforcement and learning in a way that had never been done before by putting everything in numbers and equations. Hull was also influenced by Isaac Newton’s work. Hull contributed to the motivation domain of psychology. He had quantified the Drive concept in an equation to prove that habit strength is a function of reinforcement. Edward C. Tolman was a contemporary of Hull whose theory of learning was proved to be more logical and less complicated than Hull's work. Tolman showed that behavior is goal directed and not controlled by random drives and reinforcement. Tolman used maze experiments with rats to show that rats can learn without reinforcement and are better understood as directed by goals and driven by cognitive expectancies. This finding provided a serious challenge to much of Hull's learning theory. References Further reading Chapter 4. Amsel, A., & Rashotte, M. E., eds., Mechanisms of Adaptive Behavior: Clark L. Hull's Theoretical Papers, with Commentary (New York: Columbia University Press, 1984). Hull, Clark L. (1940). Mathematico-Deductive Theory of Rote Learning. New Haven, CT: Yale University Press. . External links National Academy of Sciences Biographical Memoir Clark Leonard Hull papers (MS 294). Manuscripts and Archives, Yale University Library. 1884 births 1952