hull theories

8/4/2019 Hull Theories

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HULLBACKGROUND

Born 1884 in Akron NY

Graduated U. of Michigan in 1913

Ph.D. U. of Wisconsin 19181929-1952 Professor of Psychology at

Yale

Died 1952

Developed Hypothetico-DeductiveSystem


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HULLS APPROACH TO

THEORIZING

His approach to theory construction hasbeen called HYPOTHETICAL DEDUCTION(logical deductive).

Theory has a logical structure of postulatesand theorems.

Postulates-are general statements about

behaviour that cannot be directly verified.


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HULLS APPROACH TO

THEORIZING

From the postulates, theorems are generated.

Theorems are deduced from the postulates.

Theorems can be tested.


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MAJOR THEORETICALCONCEPTS (1943)

POSTULATE 1: Sensing the external environmentand the stimulus trace.


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MAJOR THEORETICALCONCEPTS

POSTULATE 2: The interaction of sensoryimpulses.


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POSTULATE 3: unlearned behaviour.


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POSTULATE 4: Contiguity and drivereduction as necessary conditions forlearning.


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HABIT STRENGTH

Refers to the strength of the associationbetween a stimulus and a response.

As the number of reinforced pairingsbetween a stimulus and a response goes

up, the habit strength of that associationgoes up.

THE RELATIONSHIP BETWEEN GAINS IN


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THERELATIONSHIPBETWEENGAINSINHABITSTRENGTHANDSUCCESSIVEREINFORCEMENTS


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POSTULATE 5: Stimulus generalization.


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POSTULATE 6: stimuli associated with drives.


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POSTULATE 7: Reaction potential as a function ofdrive and habit strength.


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REACTION POTENTIAL

Is a function of both HABIT STRENGTH andDRIVE.

For a learned response to occur, HABITSTRENGTH has to be activated by DRIVE.


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POSTULATE 8: Responding causes fatigue, whichoperates against the elicitation of a conditionedresponse.


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REACTIVE INHIBITION

REMINISCENCE EFFECT: theimprovement of performance following the

cessation of practice.

MASSED VERSUS DISTRIBUTED

PRACTICE: when training trials are spacedfar apart performance is superior comparedto massed practice.


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POSTULATE 10: FACTORS TENDING TOINHIBIT A LEARNED RESPONSECHANGE FROM MOMENT TO MOMENT.


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OSCILLATION EFFECT

A factor operating against the elicitation of alearned response, whose effect varies frommoment to moment but always operateswithin a certain range of values.

The oscillation effect must be subtractedfrom the effective reaction potential which

creates the MOMENTARY EFFECTIVEREACTION POTENTIAL.


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POSTULATE 11: MOMENTARY EFFECTIVEREACTION POTENTIAL MUST EXCEED ACERTAIN VALUE BEFORE A LEARNEDRESPONSE CAN OCCUR.


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POSTULATE 11: MOMENTARY EFFECTIVEREACTION POTENTIAL MUST EXCEED ACERTAIN VALUE BEFORE A LEARNEDRESPONSE CAN OCCUR.

This is called the REACTION THRESHOLD.


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POSTULATE 12:THE PROBABILITY THAT ALEARNED RESPONSE WILL BE MADE IS ACOMBINED FUNCTION OF THE MOMENTARYEFFECTIVE REACTION POTENTIAL, THE

OSCILLATION EFFECT, AND THE REACTIONTHRESHOLD.


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POSTULATE 13: THE GREATER THEVALUE OF THE MOMENTARY EFFECTIVEREACTION POTENTIAL THE SHORTER

THE LATENCY WILL BE THE LATENCYBETWEEN S AND R.


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POSTULATE 14: THE VALUE OF THEMOMENTARY EFFECTIVE REACTIONPOTENTIAL WILL DETERMINE RESISTANCE TOEXTINCTION.


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POSTULATE 15: THE AMPLITUDE OF ACONDITIONED RESPONSE VARIES DIRECTLYWITH THE MOMENTARY EFFECTIVE REACTIONPOTENTIAL.


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POSTULATE 16: WHEN TWO OR MOREINCOMPATIBLE RESPONSES TEND TO BEELICITED IN THE SAME SITUATION, THE ONEWITH THE GREATEST MOMENTARY EFFECTIVE

REACTION POTENTIAL WILL OCCUR.


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MAJOR DIFFERENCES BETWEENHULLS 1943 AND 1952 THEORIES

INCENTIVE MOTIVATION (K):

In 1943, Hull treated the magnitude ofreinforcement as a learning variable. The greater

the amount of drive reduction, the greater theincrease in habit strength.

However, experiments indicated that performance

was dramatically altered as the size ofreinforcement was varied after learning wascomplete.


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HULL (1952)

STIMULUS-INTENSITY DYNAMISM (V):

An intervening variable that varies along

with the intensity of the external stimulus(S).

The greater the intensity of a stimulus, thegreater the probability that a learnedresponse will be elicited.


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CHANGE FROM DRIVE REDUCTIONTO DRIVE STIMULUS REDUCTION

Hulls original theory was a drive reductiontheory but he modified this to a drivestimulus reduction.

He concluded that drive reduction was toofar removed from the presentation of thereinforcer to explain how learning could takeplace.

Replaced it with DRIVE STIMULI.


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FRACTIONAL ANTEDATING GOALRESPONSE

One of Hulls most important concepts.

related to secondary reinforcement.

Maze learning example


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FRACTIONAL ANTEDATING GOALRESPONSE

It is the conditioned response to stimuli,experienced prior to the ingestion of food.

via classical conditioning processes, stimuliprior to those occurring in the goal box toalso become reinforcers, and then thestimuli before them, and so on.


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HULLS FINAL SYSTEM SUMMARIZED

THERE ARE THREE KINDS OFVARIABLES IN HULLS THEORY:

1. independent variables, which arestimulus events systematicallymanipulated by the experimenter.


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HULLS FINAL SYSTEM

SUMMARIZED

2. Intervening variables, which areprocesses thought to be taking place withinthe organism but are not directly

observable.

3. Dependent variables, which are someaspect of behaviour that is measured by the

experimenter in order to determine whetherthe independent variables had any effect.


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SUMMARY OF HULLS THEORY

OF LEARNING AFTER 1952


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EVALUATION OF HULLS THEORY

No theory has been more thoroughly scrutinized,attacked, and dissembled more than Hulls.


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CONTRIBUTIONS

One strength was the possibility of falsifying its variouspropositions.

He was willing to take risks in theory construction.

The drive reduction hypothesis was the first attempt to breakfrom the imprecise definitions of satisfiers/reinforcers thatcharacterized both Thorndikes and Skinners theories.

He was also the first to make precise predictions about jointeffects of learning and drive on behaviour and about the

effects of fatigue (reactive and conditioned inhibition).


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CRITICISMS

Little value in predicting behaviour outside of thelaboratory.

Insisting that all concepts of interest beoperationally defined.

For making inconsistent predictions.

Hull did not revise his theory enough in the face of

problematic data and may have ignored manycontradictory results.


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THANKYOU

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hull theories

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