4 Neobehaviorist Psychologists Edward Tolman Edwin Guthrie Clark

4 Neobehaviorist Psychologists Edward Tolman Edwin Guthrie Clark Hull B. F. Skinner 1

Edward Tolman ¡ Cognitive behaviorism ¡ 1911 - Graduated from MIT with a degree in electrical chemistry ¡ 1915 – Graduated from Harvard with a Ph. D in psychology ¡ Most influenced by Robert Yerkes who used Watson’s textbook and who rejected the use of introspection 2

Edward Tolman ¡ ¡ Taught at Northwestern 1915 – 1918 when he was fired for pacifist activities Moved to Cal – Berkley where he taught for 40 years 3

Edward Tolman’s Psychology ¡ ¡ ¡ Studied the behavior of rats running in mazes Determined that the rats’ behavior was more than building S -> R connections Rats behaved with intelligence and purpose 4

Purposive Behavior ¡ ¡ Watson excluded purpose and cognition from psychological study – Tolman felt this was an error Attempted to develop a behaviorism based on objective behavior, but included the purpose of behaviors 5

Purposive Behavior in Animals and Men ¡ Most of the book concerned rat behavior in mazes ¡ Completely rejected mentalistic psychologies and endorsed behaviorism ¡ Psychology should be the study of objective behavior and it should include behaviors that are purposive, goaldirected and cognitive 6

Example of a purposive behavior ¡ When a rat learns to run a maze it not only expects to get a reward, but learns that a specific reward will be there ¡ Different rewards have different values to the animal ¡ When reward was switched to a less valued reward, rats ran slower and made more errors 7

Latent learning and cognitive maps ¡ 1929 - Rats were placed on a maze with no reward and then later given a reward l l l ¡ Control group – food in the goal box on all 7 days Ex. group 1 – no food for 1 st 6 days, food in goal box on day 7 Ex. Group 2 – no food for 2 days, food available on day 3 - 7 Results: experimental groups performed like the control the day after the transition from no food to food in the goal box 8

Latent learning and cognitive maps ¡ Conclusion: rats must have learned the maze during the unrewarded trial, and they developed a cognitive map of the maze. ¡ Tolman referred to this as latent learning ¡ Learning without reinforcement a major problem for more radical behaviorists 9

Law of least effort ¡ Rats placed on an elevated maze with no walls and allowed to explore ¡ 3 routes to the goal box that were of different lengths ¡ Rats then made hungry and placed on the maze – they chose the shortest route ¡ Block the shortest route, they took the second shortest, etc. ¡ Conclusion: their cognitive map included the whole maze not just one route 10

1937 – Place Learning ¡ ¡ Presented in his APA presidential address Use of a plus maze to determine how rat solve mazes 11

Response versus place learning ¡ Modified plus maze ¡ Response learning: start at either S 1 or S 2 – food always found by turning left ¡ Place learning: Start at either S 1 or S 2 – food always at F 1 or at F 2 ¡ Results: response learning very slow; place learning very rapid 12

Tolman’s model ¡ Three variables influence behavior: l l l ¡ Independent variable – conditions of the experiment – what is controlled Intervening variables – subject variables, age, skill, past experiences Dependent variable – what is measured Behavior as measured by the dependent variable is a function of the independent and intervening variables 13

Two major criticisms of Tolman ¡ ¡ He did not develop a true theory of learning showing a clear theoretical position Objection to his writings as being subjective and mentalistic 14

2 important contributions of Tolman ¡ ¡ Support of the rat as appropriate subjects for psychological study Most important was his realization that Watson’s behaviorism had “thrown out the baby with bath water” in rejecting all mentalism 15

Edwin Guthrie and Clark Hull 2 very different people ¡ Guthrie received a degree in mathematics, but became more interested in philosophy ¡ He read Bertram Russell and Whitehead’s Principia Mathematic and decided the use of deduction in philosophy would never lead to an understanding of the mind ¡ 16

Clark Hull ¡ A well-known psychologist who had studied aptitude testing and hypnosis for 12 years when he read Principia Mathematic ¡ He felt this work could serve as a model for a psychological system of behavior ¡ Both became behaviorists, but for 2 different reasons 17

Edwin Guthrie ¡ 1912 - Ph. D in philosophy ¡ Changed from an interest in the association of ideas to the more behavioral perspective of the association of responses ¡ Very similar opinions to those of Watson – minimized the importance of reinforcement maximized the importance of contiguity 18

Contiguity Theory ¡ ¡ ¡ Behavior is a function of the environment If food is available, an animal will emit responses to obtain it – successful responses will be learned The S->R association is learned through one trial learning 19

The role of reinforcement ¡ Reinforcement (getting the food) is only important because it ends the activity ¡ The last act is the one that is learned and that learning persists ¡ Unsuccessful acts are not learned because they are displaced by later successful acts 20

Studies supporting contiguity theory ¡ ¡ Prevailing theory – animals would learn a task to maintain homeostasis Guthrie showed that rats would learn a task to get water sweetened with saccharin. No nutritional or survival value 21

Studies supporting contiguity theory ¡ ¡ Male rats will learn to run a maze if a receptive female is in the goal box. Even if they are prevented from copulating Both presented as evidence of animals learning without being reinforced – indicating that reinforcement was not important 22

Movements versus whole acts ¡ Guthrie proposed: l l Watson and others studied whole acts because they were easy to measure Movements that make up whole acts should be studied Individual movements are learned in one trial learning Putting these individual movements to create whole acts requires practice 23

Criticisms of Guthrie's Contiguity theory ¡ Early appeal of his theory was it’s simplicity ¡ This simplicity was later criticized for ignoring or failing to address problems in learning his theory couldn’t explain – he had “mistaken incompleteness for simplicity” ¡ Theory based on very little experimental data. Took a more philosophical approach to theorizing 24

Clark Hull ¡ His goal was to develop universal laws of behavior ¡ Major enduring contribution to psychology was the application of formal logic to psychological problems l l l Form theoretical suppositions or constructs Develop predictions of theory Test predictions 25

Hull’s behaviorism ¡ Greatest influences were Darwin’s theory of evolution - Importance of adaptability, natural selection, and continuity of behavior in evolution He did not study species specific behaviors ¡ Looking for universal laws that could explain both human and nonhuman behavior ¡ ¡ Mathematics: attempted to develop very complex mathematic formulas that could predict behavior 26

The importance of intervening variables ¡ ¡ Watson and others were interested in describing the formation of the connections between stimulus and response Hull more interested in the nature of the connections (habit strength) and the variables that influenced their development 27

Hull’s concept of reinforcement ¡ Watson – reinforcement was only important in that it kept the animal on task ¡ Guthrie – it ended the behavior and the last behavior was learned ¡ Hull – reinforcement strengthened the connection between a stimulus and a response 28

Hull’s concept of reinforcement ¡ Positive reinforcement – anything that reduces tension ¡ Negative reinforcement – creates tension to be avoided ¡ Two issues to be addressed: l l Motivation had to be part of reinforcement His approach had to hold for both humans and nonhumans 29

The concept of drive ¡ Reinforcement meant the reduction of a drive state ¡ If drive increased, then the level of response would increase to decrease the level of drive ¡ Different species may have different drives, but reduction of drive was the basis of reinforcement 30

Basis of Theory ¡ 1. Habit strengths could form in a single trial, but were strengthened through repetition and reinforcement ¡ Complex behaviors : different stimuli may become associated with other stimuli and with more than one response l l The habit strength between the stimulus and different responses differed The response evoked by a stimulus depended on which response had the greatest habit strength 31

2 additional variables added to formula ¡ ¡ Incentives – some objects were more preferred – 2 objects may both reduce drive, but one increases the speed of learning because it is more preferred Inhibition l l Reactive inhibition Conditioned or learned inhibition 32

Criticisms of Hull’s drive reduction theory ¡ Behaviorists – too much reliance on intervening variables – incentives, drives, etc. not observable ¡ Humanists – dehumanizing humans and ignoring individual differences ¡ His mathematic formulas called fantasies because they assume learning is a continuous process when it is not 33

Hull’s contributions ¡ ¡ Previously mentioned – system of formal logic used in psychology His theories and ideas were so clear and well formulated that they became excellent targets for others 34

B. F. Skinner – the radical behaviorist ¡ 1930’s and 1940’s Guthrie and Hull were the leading behaviorists in psychology ¡ 1950’s and 1960’s behaviorism dominated by Skinner ¡ Tolman’s works were neglected for this period, but later became important for the development of cognitive psychology 35

Influences on Skinner ¡ ¡ Neurophysiologists Pavlov and Sherrington – study of the reflex Watson’s behaviorism 36

Operant conditioning ¡ Classical conditioning – the animal responds to the environment – learning results from the environment ¡ Operant conditioning – the animal operates on the environment – the animal performs arbitrary behaviors and if a behavior is rewarded it will occur again ¡ The animal controls the response rate not the experimenter 37

Schedules of reinforcement ¡ ¡ Accidental beginning – he was studying the nature of reinforcement and only had enough food for a few trials 3 different schedules l l l Continuous Ratio – fixed and variable Interval – fixed and variable 38

Other contributions ¡ ¡ System of behavioral training called shaping – use of successive approximations Behavior modification training 39

Skinner and controversy ¡ Skinner sought out controversy ¡ Walden II – utopian society based upon behavioral control ¡ When asked if his house was on fire and he could save his children or his books, he replied he would save his books. His writings would make greater contributions than his genes ¡ Heir conditioner ¡ Strongly attacked public education practices 40