CHAPTER 13 – FOUR NEOBEHAVIORIST PSYCHOLOGISTS Dr. Nancy Alvarado Four Neobehaviorists The four neobehaviorists described in this chapter (Tolman, Guthrie, Hull, Skinner) accepted Watson’s: Rejection of consciousness His definition of psychology as the science of behavior His insistence on objective, observational data. These four had similarities but also many important differences from each other. As a result, the Behaviorist movement was extremely productive in terms of theory and research. Edward Chace Tolman (1886-1959) Tolman grew up in Newton MA and went to MIT, graduating with a degree in electrochemistry. William James “Principles of Psychology” changed his life – he went to Harvard & studied with Munsterberg. Tolman was troubled by why introspection was so rarely used in his lab, although taught as a methodology. A class with Yerkes focused his attention on behavior. He spent a month in Germany with Koffka & was influenced strongly by Lewin. He taught at Northwestern, then at UC Berkeley. Edward Chace Tolman Tolman Hall at UC Berkeley Tolman’s Cognitive Behaviorism At Berkeley, Tolman taught comparative psych using Watson’s book as a text. He disagreed that rat behavior was mechanistic, considering rats intelligent and purposeful. He believed rats learned the general layout of a maze, forming a “cognitive map.” He developed a “molar behaviorism” concerned with purpose and cognition – both excluded by Watson. However, his book “Purposive Behaviorism” began with an attack on mentalistic psychology. Rats Have Purpose Tolman & his students showed that: Rats have preferences and run fastest for rewards they like better (bread and milk not sunflower seeds). Rats are disappointed if they get a less valued reward previously expected due to training. Monkeys were similarly disappointed by a lettuce leaf in place of a banana. Rats use prior experience when unrewarded to increase their behavior later when rewarded – latent learning. What is a reward critics asked? Latent Learning Results Rats Have Insight Tolman & Honzik gave unrewarded rats experience with a complex maze, then found that they use the shortest route when rewarded. Law of least effort – given a choice of several paths, rats use insight to find the one requiring least effort. Rats remember where something is located, not a series of turns (responses). Two groups – one (Place) always found food in the same place; the other (Response) always found food by turning in the same direction. Place rats learned faster. Tolman’s Mazes S2 curtain F2 F1 curtain S1 Tolman’s Theoretical Model Tolman published over 100 papers and 2 books. He proposed a model of independent, intervening and dependent variables that is widely used in experimental psychology. IVs are manipulated by the experimenter and influence intervening variables such as appetite or motor skill. Subject IVs (age, heredity) are held constant. DVs (running speed, number of errors) are measured by the experimenter. Tolman’s General Concerns Tolman tried to relate his rat-runner’s psychology to broader human problems such as aggression or war. In 1949, he supported younger colleagues required to take a loyalty oath, refusing to take it himself. Tolman was APA President in 1937 and a member of the National Academy of Sciences. Tolman liberated Behaviorism from Watson’s methodological and theoretical constraints. Contemporary behaviorists no longer view animals as passive, mechanical systems but active info processors. Edwin Ray Guthrie (1886-1959) McDougall classified Behaviorists as “strict, near or purposive” types. Guthrie was “near.” Guthrie graduated in math, then studied psychology at Univ. of Nebraska with Wolfe. He finished his Ph.D in philosophy with Singer at Univ. of Penn. He doubted that deduction could lead to an understanding of the human mind. He taught math briefly then accepted a position at Univ. of Washington, transferring to psychology in 1919 and becoming a professor in 1928. Edwin Ray Guthrie Learning Through Contiguity Guthrie proposed that “Stimuli which accompany a response tend, on their recurrence, to evoke that response.” The simplicity of this was appealing as the ideas of other theorists became increasing complex. Association through contiguity goes back to Aristotle, Bain & Hartley (British Associationists). Reward does not cause learning – it protects it against unlearning because the situation changes. Guthrie also proposed single-trial learning. Guthrie’s Approach Guthrie was able to provide clever explanations of a variety of learning phenomena (effects of reward and punishment, practice, trace conditioning). Punishers elicit actions – these actions are learned. Improved behavior occurs with practice because the constituent movements become better with repetition. “Learning does not disappear with lapses in time but due to new learning which erases the old.” Sleep prevents learning of new associations. Pavlov’s Criticism of Guthrie To explain delay & trace conditioning, Guthrie suggested that the stimuli accompanying salivation are not the CS (bell) but the orienting response (listening, turning head, pricking up ears). In reply, Pavlov wrote and angry response -- “The Reply of a Physiologist to Psychologists,” his only paper published in an American psychology journal. He said the “listening” response was nonexistent because dogs were not alert during the trace gap and because the orienting response quickly disappears – there are no mysterious latencies in the nervous system. Guthrie’s Examples Dogs encountering meat with embedded mousetraps become suspicious of the meat because of the almost perfect contiguity. A daughter made to re-enter and hang up her coat changes behavior because of the new association. Other examples of pastor’s horse trained to lunge when he said “whoa” (which means stop); breaking horses with successive weight on its back (contiguity). Signals to smoke (finishing a meal, starting work). Cats in a Puzzle Box Performing 800 escape responses, Guthrie observed that cat responses were highly stereotypical (the same each time). He suggested that cats had learned to associate that specific movement with escape from the box. Critics suggested the movement was stereotypical because it was instinctive (species typical) to greet others by rubbing against them. Guthrie’s Clinical Views Guthrie published “The Psychology of Human Conflict” in 1938. He translated Pierre Janet’s “Principles of Psychotherapy” and preferred Janet’s idea of force mentale to Freud’s ideas about the subconscious. Everyone has a certain amount of energy (force). When it is depleted by crises, neuroses appear. Mental health requires maintaining a balance of mental energy. Clark Leonard Hull (1884-1952) Hull was born on a farm but worked hard to become more than a “chore boy.” He was intensely self-critical and had poor health (polio, typhus). He originally studied mining engineering but a paralyzed leg ruled that out. He entered grad school at Univ. of Wisconsin, working with Joseph Jastrow, who had studied with G. Stanley Hall. His dissertation taught subjects associations to Chinese characters. He then became a lecturer at Wisconsin. Clark L. Hull Research on Aptitude Testing Assigned to teach a class on psychological testing, he became interested in validating existing tests. His attempt to develop a universal aptitude test failed. Hull built a correlation machine to avoid doing the laborious calculations by hand. His machine predated calculators and computers and is now in the Smithsonian Museum in Washington D.C. Without access to sufficient subjects to validate his tests, he abandoned aptitude testing as a research interest. Research on Hypnosis Teaching classes to medical students, Hull became interested in the role of suggestibility in medical cures. Jastrow shared that interest – as a skeptic. He attempted to improve the quality of experimental work done to investigate hypnosis, wary of fraud. He believed susceptibility to hypnosis was normally distributed in the population with little correlation with other traits or sex. Children slightly more susceptible. He found that hypnosis did not improve memory. His book Hypnosis & Suggestibility is still used as a text. Hull’s Behavior System Hull’s most significant contribution to psychology was his development of a comprehensive behavior system – a model of how behavior occurs. At Yale, Hull intensively studied Newton’s Principia and philosophers like Bertrand Russell and Alfred North Whitehead, Hobbes, Lock, Hume, Kant & Leibnitz. Spence (Hull’s student) described his system as “a Herculean elaboration of [Woodworth’s] S-O-R formula” (Stimulus – Organism – Response). He conceptualized humans as elaborate machines. Hull’s Drive Theory He attempted to extend the principles of classical conditioning to instrumental trial and error learning. He accepted the idea of reinforcement based on drive reduction. His theory was presented in “Principles of Behavior.” His theory had 17 postulates and 17 corollaries. It included intervening variables for habit strength, stimulus intensity, drive level, incentive value of the reward to determine output latency, reaction amplitude. He led an impressive program of experimentation. Evaluating Hull’s Theory It was successful at stimulating new research. Some questioned whether the limited range of experimental situations used in his research could shed light on more generalized behavior. Can a theory of behavior