THE EFFECTS OF BEHAVIOR :THORNDIKE AND HULL

SNU CSE 2008-22937 Son, Suil

Contents

Edward L. Thorndike : Connectionism Thorndike’s Pre-1930s Theory : Emphasis on

Practice Thorndike’s Post-1930 Theory : Emphasis on

Reinforcement Overview of Hull's system Variables of Hull’s System Hull’s system : Input Variables: Predictors Hull’s system : Intervening Variables Hull’s system : Output Variables : The Predicted Modification of Hull’s system Appraisal of Thorndike's Connectionism Appraisal of Hull's Formal Behaviorism

Question

What is the most important factor of Thorndike and Hull’s learning theory?

What is the major problem of Thorndike’s learning theory?

What is the major problem of Hull’s learning theory?

Edward L. Thorndike(1874-1949) : Connectionism Thorndike’s experiment

: Puzzle Boxes and Animal Intelligence Cat can not open the puzzle boxes Animals were allowed to see a trained animals behavior

They will not learn that behavior Animals learn through trial and error. Connection between the response and the situation

Contiguity or Reinforcement Contiguity : an association is formed between stimuli and

responses Reinforcement : the consequences of the behavior

leads to pleasant consequences eliminates something unpleasant

Thorndike's Pre-1930s Theory: Emphasis on Practice Emphasizes experimentation rather than introspection Emphasizes behavior rather than thought Learning consists of the formation of bonds between

stimuli and responses: bonds that take the form of neural connections ->

connectionism Learning invloves stamping in of stimulus-response

connections Forgetting invloves stamping out connections

Three important variables recency frequency Contiguity

Thorndike's Pre-1930s Theory Law of Exercise

Bonds between stimuli and responses are strengthened through being exercised "frequently," "recently," and "vigorously"

Law of Effect The most important law A connection is stamped in its consequences(its effects) than how often it is

exercised 1. Responses just before a satisfying state of affairs are more likely to be repeated

Satisfiers 2. Responses just before an annoying state of affairs are more likely not to be

repeated Annoyers

A model of instrumental learning The connection is formed between the stimulus and the responses rather than

between the reward and the response

Law of Readiness This law has to do mainly with the learner's motivation (forces that lead to

behavior) Certain behaviors are more likely to be learned than others

Thorndike's Pre-1930s Theory Subsidiary Laws

1. Multiple Responses The organism will respond in a variety of ways if its first response does not

lead immediately to a more satisfying state of affairs -> trial and error

2. Set or Attitude Learning is partly a function of attitude or set

3. Prepotency of Elements It is possible for a learner to react only to the significant(prepotent) elements

in a problem situation

4. Response by Analogy When a person is placed in a novel situation, they transfer the situation to

similar one theory of identical elements

5. Associative Shifting stimulus substitution It is possible to shift a response from one stimulus to another.

Thorndike's Post-1930 Theory: Emphasis on Reinforcement

He made some major modifications on his theory Repeal of Law of Exercise

Mere repetition does not cause learning realized through experimentation with humans

Half a Law of Effect Satisfier strengthen the connection Annoying outcomes do relatively little to the strength of a connection

Learning by Ideas Account observation about human learning Thoughts or ideas are important in human learning Investigated Two additional concepts

1. principle of belongingness If two or more elements are seen as belonging together, they are more easily learned

2. spread of effect A response is followed by as satisfying state of affairs, other related responses also seem to be affected.

Overview of Hull's system

Hull is the most ambitious of the behavior theorists Hull dream to use the rules of logic and of experimentation to

discover and to deduce the laws that govern human behavior He designed hypothetico-deductive system

based on 17 laws(postulates) All theorems and corollaries derived from 17 postulates Hull’s main concern was to derive specific, testable hypotheses from

the 17 postulates Hull summarized the components of learning into 3 categories

Conditions(Stimuli) -> input variables : observed and measured Responses -> output variables : observed and measured Organism -> intervening variables : purely hypotherical

inferred from input and output What might be happening between the presentation of a stimulus and the occurrence of a

response

He believed that all behavior consists of S-R connections He believed that human behavior could be predicted if psychologists

had the right information and the right equations.

Hull’s System

Variables of Hull’s System

Type Name MeaningsInput Variable N Number of prior reinforcements

CD Driver condition

S Stimulus intensity

w Amount of reward

W Work involved in responding

Intervening variables SHR Habit strength

D drive

V Stimulus-intensity dynamism

K Incentive motivation

SER Reaction potential

SI!R Aggregate inhibitory potential

SE!R Net reaction potential

sLr Reaction threshold

sOr Oscillation of reaction potential

Output variables R The occurrence of a response

StR Response latency

A Response amplitude

N Number of nonreinforced trials to extinction

0 No response

Hull’s system : Input Variables: Predictors Input variables are predictors They represent the information the psychologist needs to correctly

predict how a person will respond Input variables represent a stimulus. Complex product of a large number of preceding events

N : Number of prior reinforcements How many times in the past the S-R bond in question has been reinforced

S : stimulus intensity Something about the physical intensity of the stimulus

CD : driver condition the drive conditions of the organism

w : amount of reward W : work invloved in responding

the amount of work required in responding

The major difficulties is that the psychologist needs a tremendous amount of knowledge about the subject's experiences.

Hull’s system : Intervening Variables They intervene between stimulus events and response events to determine whether

a response will occur for a stimulus. A mathematical description of S-R relationships 1. sHr : habit strength

the most important the strength of the bond between a specific stimulus and response a function of reinforcement rather than of simple repetition.

2. D : drive Drive is a motivational concept closely tied with reinforcement.

Primary drives : Those associated with physiological needs such as the need for food or water

Secondary drives : Conditioned to primary drives through contiguity - high grades or money

Two components 1. drive proper 2. inanition component

3 central functions 1. It provides for reinforcement, without which learning would not occur 2. It activates habit strength 3. Drive stimuli become attached to specific behaviors through learning

Hull’s system : Intervening Variables 3. V : stimulus-intensity dynamism

determine the probability of a response

4. K : incentive motivation is determined by amount of reward( w as an input variable) drive alone could not account for motivation

5. sEr : reaction potential sEr = sHr * D * V * K

if the value for any of them is zero, reaction potential will also be zero. And a response will not occur

identical changes in one of these variables will have different absolute effects, depending on the values of the other variables.

a minimum amount of potential is required before behavior will take place.

Increasing reaction potential will be reflected in shorter response latency(StR), more response amplitude(A), and longer extinction time(n)

Hull’s system : Intervening Variables 6. sE!R : net reaction potential

prior reinforcements or intensity of the stimulus the result of subtracting the individual's tendency not to respond

7. sI!R : aggregate inhibitory potential the tendency that the organism has not to respond reactive inhibition plus conditioned inhibition Its effect is to lower the net reaction potential until eventually the

response no longer occurs. 8. sLR : reaction threshold

the magnitude that net reaction potential must exceed before a response will occur

If sE!R > sLR, a response, R, occurs; if sE!R < sLR, no response occurs 9. sOR : oscillation of reaction potential

Hull’s system : Output Variables : The Predicted

Variables stR : response latency

A : response amplitude n : the number of nonreinforced responses that would occur before

extinction R : the occurrence of a response 0 : nonoccurrence of response

If sEr > sLR, then R sEr = (sHr * D * V * K) - sI!R

If net reaction potential is greater than the threshold, a response will occur

net reaction potential is the product of habit strength, drive, stimulus-intensity dynamism, and incentive motivation, minus aggregate inhibitory potential

Modification of Hull’s system Fractional Antedating Goal Reactions

A conditioned response made by an organism before the actual goal reaction

Stimuli that maintain behavior toward a goal

Habit-Family Hierarchies an individual will learn a number of different

responses for the same stimulus. each response will lead to the same goal

Family - same goal Hierarchy

one alternative will usually be preferred over another reaction potential is higher

Appraisal of Thorndike's Connectionism His laws and principles present a relatively clear picture of his

view of learning Learning consists of the formation of physiological bonds or

connections between stimuli and responses Humans arrive at appropriate responses largely through trial and

error Made significant contributions in the practical application of

psychological principles, particularly in teaching Critics

His theory is based on informal observation He appealed to vague, internal states as a basis for explaining learning

annoying state satisfying state

Appraisal of Hull's Formal Behaviorism An organism placed in the same situation on different occasions

will generally respond in the same way each time If the response is different but the situation is identical, it means

that the organism has changed Main problem is the near impossibility of arriving at precise

mathematical functions for each of the variables in the equation. Despite the impressive logic and mathematics that are

fundamental to the Hull system, the theory does not fare particularly well with respect to some of human learning criteria

But Hull's system contributed in many tangible ways to the advancement of psychological theory Introducing concepts such as fractional antedating goal reactions Hull has profoundly influenced how psychological investigations are

conducted The importance of reinforcement

The End

Thank you

Question

What is the most important factor of Thorndike and Hull’s learning theory?

What is the major problem of Thorndike’s learning theory?

What is the major problem of Hull’s learning theory?