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Instrumental Conditioning: Foundations
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Name Game Instrumental: subject instrumental in producing outcome Operant: subject operates on environment to produce outcome
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Elements Discriminative stimulus (S D ) Response Outcome –Appetitive –Aversive Species and individuals
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Outcomes and Effects Positive –Something is delivered Negative –Something is removed Reinforcer –Causes frequency of behaviour to increase Punisher –Causes frequency of behaviour to decrease Need to know effect on behaviour before labeling “reinforcer” or “punisher”
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Omission Training Negative punishment Text: withdrawing sources of positive reinforcement Omission training technique –Operant response --> withholding of appetitive stimulus –No operant response --> get appetitive stimulus
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A Caveat Domjan: picky on operant vs. instrumental (e.g., p. 151) Domjan: sloppy on reinforcer and punisher re: effect on behaviour Don’t be sloppy like Domjan! Be clear on outcome’s effect on increase/decrease of behaviour!
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Methodologies/Procedures Discrete trial –One trial at a time –Reset apparatus –Latency, running speed, reduction in errors Free operant –Uninterrupted repeated trials –Less disruptive for subject –Response rate
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Beginnings Edward L. Thorndike Undergraduate student Animal intelligence Mazes Puzzle boxes (video)video Trial-and-error learning
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Law of Effect Responses followed by appetitive outcomes increase in frequency Responses followed by aversive outcomes decrease in frequency Stimulus-Response (S-R) learning Association between S and R altered by experience
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Mechanical Strengthening Processes Guthrie & Horton (1946) Cat in box with a pole Streotypic behaviours Consistent in individual Variable across individuals
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Stop-Action Principle “Random” response strengthened by success –Individual predispositions –E.g. response = bite pole; appetitive outcome = escape –“Stops the action” Not immediate Dominance of one response
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Problems with Stop-Action Muezinger’s (1928) Guinea pigs Lever press for lettuce Not one dominant operant behaviour
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Response Classes Lashley (1942) Reinforcement strengthens class of operant responses End goal
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B.F. Skinner Operant response –Meaningful, measurable unit of behaviour –Defined by effect it has on environment Skinner’s approach ( video)video Operant chamber (video)video
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Shaping Trial-and-error somewhat random Successive approximations Very precise operant response possible
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Shaping: Reinforcers Conditioned reinforcer –Previously neutral stimulus that has acquired the capacity to strengthen responses because it has been repeatedly paired with a primary reinforcer Primary reinforcer –Stimulus that naturally strengthens any response that is paired with it
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Shaping a Lever Press Gradual process Reinforce more appropriate/precise responses
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Behavioural Stereotypy vs. Variability Always some slight variability in responses Degree of stereotypy –Specific imposed response requirements –Cost-benefit of different responses Can actually condition response variability –E.g., Only reinforce novel responses
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Page & Neuringer (1985) Pigeons 8 pecks on two keys (left and right) Exp. Gr.: only reinforced if response different from previous 50 responses Control Gr.: reinforced for any response pattern % novel responses 1 st five sessions last five sessions Expimental Control
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Mediators on Response Belongingness –Thorndike: some responses harder to condition than others Biological predispositions Breland & Breland (1961) and instinctive drift
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Skinner (1948) Superstitious behaviour Accidental strengthening of response FT-15 sec. grain delivery 6 of 8 pigeons develop very characteristic, unrequired responses Humans –Rituals, personal and society superstitions; persistent
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Staddon & Simmelhag (1971) High speed cameras Interim and terminal responses Behavioural regularities Temporally structured Terminal: species specific behaviours re: food anticipation Interim: behaviours not motivated by food
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Responses R3: peck at floor R4: quarter turn R8: move along magazine wall R1: orient toward food magazine wall R7: peck at magazine wall Probability of Occurrence Interval (sec.) terminal interim
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Behaviour Systems Theory Periodic food delivery activates feeding system Preorganized species-typical foraging and feeding responses Just after food: post-food focal search Middle of time interval: general search
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Reinforcer Values Response magnitude, rate of learning Quantity and quality –Individual’s level to assess magnitude differences –Generally positive correlation for single operant tasks; more complicated for higher schedules (back to this with choice section) Changes in reinforcement magnitude –Reinforcement history –Expectation –Positive and negative behavioural contrast
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Response-Reinforcer Contingency “Causal relation” Strong contingency produces stronger responding and faster learning Non-contingent (random) relationship –Lack of responding –Extinction
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Temporal Contiguity Immediate reinforcement more effective than delayed –Which response was reinforced? forgetting; reinforcer devaluation Skinner on teaching machine (video)video Bridge (conditioned reinforcer) Marking procedure
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Control Response’s control over outcome Uncontrollable situation Aversive outcome Learned helplessness
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Triadic Design Immunization –Escapable shock; inescapable shock, escape- avoidance; rapid avoidance GroupExposure Phase Conditioning Phase Result Group EEscapable shock Escape- avoidance Rapid avoidance Group YYoked inescapable shock Escape- avoidance Slow avoidance Group RRestricted to apparatus Escape- avoidance Rapid avoidance
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Theory Behaviour has no effect on situation Generalization Maier & Seligman (1976) –Motivational, cognitive, and/or emotional impairment Non-human learned helplessness –Model for human depression –Situation (specific/global), Attribution (internal/external), time (short- or long-term)
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