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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?