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

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

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. 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

Hull’s System

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

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

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 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 Hull’s major explanation for learning is reinforcement

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

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?