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4 Neobehaviorist Psychologists

Edward TolmanEdwin GuthrieClark HullB. F. Skinner

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Edward Tolman

Cognitive behaviorism

1911 - Graduated from MIT with a degree in electrical chemistry

1915 – Graduated from Harvard with a PhD in psychology

Most influenced by Robert Yerkes who used Watson’s textbook and who rejected the use of introspection

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Edward Tolman

Taught at Northwestern 1915 – 1918 when he was fired for pacifist activities

Moved to Cal – Berkley where he taught for 40 years

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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

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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

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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, goal-directed and cognitive

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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

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Latent learning and cognitive maps

1929 - Rats were placed on a maze with no reward and then later given a reward Control group – food in the goal box on all 7

days Ex. group 1 – no food for 1st 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

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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

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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

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1937 – Place Learning

Presented in his APA presidential address

Use of a plus maze to determine how rat solve mazes

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Response versus place learning

Modified plus maze

Response learning: start at either S1 or S2 – food always found by turning left

Place learning: Start at either S1 or S2 – food always at F1 or at F2

Results: response learning very slow; place learning very rapid

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Tolman’s model

Three variables influence behavior: 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

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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

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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

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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

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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

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Edwin Guthrie

1912 - PhD 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

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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

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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

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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

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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

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Movements versus whole acts

Guthrie proposed: 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

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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

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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 Form theoretical suppositions or constructs Develop predictions of the theory Test predictions

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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

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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

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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

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Hull’s concept of reinforcement

Positive reinforcement – anything that reduces tension

Negative reinforcement – creates tension to be avoided

Two issues to be addressed: Motivation had to be part of reinforcement His approach had to hold for both humans and

nonhumans

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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

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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 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

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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 Reactive inhibition Conditioned or learned inhibition

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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

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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

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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

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Influences on Skinner

Neurophysiologists Pavlov and Sherrington – study of the reflex

Watson’s behaviorism

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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

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Schedules of reinforcement

Accidental beginning – he was studying the nature of reinforcement and only had enough food for a few trials

3 different schedules Continuous Ratio – fixed and variable Interval – fixed and variable

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Other contributions

System of behavioral training called shaping – use of successive approximations

Behavior modification training

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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