1. The Effects of Behavior : Thorndike and Hull
SNU CSE Son, Suil

2. 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

3. 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?

4. 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

5. 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
Traditionally two types of statements
those that have to do with consciousness
uncertain, difficult
those that have to do with behavior

6. 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

7. 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.
As a result of his many experiments with both human and nonhuman animals, the arrived at several additional laws of learning

8. 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.

9. 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.
His dream was to use the rules of logic and of experimentation to discover and to deduce the laws that govern human behavior
Science two aspects
the actual observations of the discipline
tries to make sense of the observations by organizing them into a coherent, logical system or theory

10. Hull’s System

11. Variables of Hull’s System
Type
Name
Meanings
Input 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
Number of nonreinforced trials to extinction
No response

12. 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.

13. 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

14. 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)
K :
by Crespi 1942
1,2,3 most feed -> ran fastest
3,3,3 previous least feed -> ran fastest

15. 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

16. Hull’s system : Output Variables : The Predicted
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

17. 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
Hull’s major explanation for learning is reinforcement

18. 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
There are many things to fill the gaps and fix the defects

19. 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

20. The End
Thank you

21. 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?