PSY402 Theories of LearningContemporary TheoriesContemporary Theories (Cont.)Stimulus-Substitution TheoryConditioned Opponent ResponseDrug Tolerance OverdosesSOP TheoryTwo-Phase ReactionsMore Support for SOP TheoryAffective Extension of SOP TheoryRescorla-Wagner TheoryUCS Preexposure EffectProblems with Rescorla-WagnerMore ProblemsComparator TheoryAttentional ViewRetrospective ProcessingSlide 18Operant ConditioningProbability-Differential TheoryResponse Deprivation TheoryBehavioral AllocationProblems with ContingenciesChoice BehaviorDelayed GratificationComplexities of the Matching LawPSY402Theories of LearningMondayDecember 1, 2003Chapter 9 – Contemporary TheoriesContemporary TheoriesShift from global theories (e.g., Hull’s drive theory) to theories about specific aspects of learning.Global theories were about operant responding not classical conditioning.An animal’s biology influences whether, what, and how fast it can learn.Cognitive view requires emphasis on specific cognitive processes.Contemporary Theories (Cont.)Classical Conditioning:Nature of the CR – stimulus substitution theory and SOP theoryPredictiveness of the CS – Rescorla-Wagner associative model, comparator theory, attentional theory, retrospective processing approach.Operant Conditioning:Nature of reinforcementBehavioral economicsStimulus-Substitution TheoryWhat is the nature of the CR – is it just the UCR or is it different?Pavlov – stimulus-substitution theory:The CS stimulates the same areas of the brain as the UCS, producing the same response.Activation of CS with UCS establishes neural connection between brain areas.Conditioned Opponent ResponseThe CR and UCR are often different:CR of fear is different than UCR of pain.Siegel – best evidence of difference:Morphine (UCS) produced analgesia, reduced pain (UCR) Light or tone (CS) produced hyperalgesia, increased pain (CR).Rats remove paws from heat quickly with CS, slowly with UCS.Insulin (glycemia) works the same wayDrug Tolerance OverdosesElimination of a CS results in a stronger response to the UCS, drug.Extinction of responding to environ-mental cues strengthens drug responseChanging the context in which a drug is administered increases response to the drug.Novel environment does not elicit an opponent CR.SOP TheorySometimes Opponent-Process theory (SOP) – explains why CR varies.UCS elicits primary A1 (fast) and secondary A2 (longer) responses.A1 & A2 can be same or different.Conditioning only occurs to A2 – the CR is always an A2 response.When A1 & A2 differ, UCR & CR differ.Two-Phase ReactionsShock – results in:A1 -- Initial agitated hyperactivityA2 -- Long-lasting hypoactivity (freezing)CER elicited by CS is A2Morphine – results in:A1 – sedation or hypoactivityA2 – hyperactivity two hours laterCR elicited by CS is hyperactivityMore Support for SOP TheoryRabbit eyeblink mechanisms support the idea of two-phases.Backward conditioning – learning occurs if the CS is presented just before the peak of the A2 response.Larew – conditioning occurred with a 31 sec lapse but not 60 sec or 1 sec.Affective Extension of SOP TheoryWhy do different A2 responses have different optimal CS-UCS intervals?Two distinct UCR sequences activate distinct A1 & A2 sequences:SensoryEmotiveThese distinct sequences can have different strengths, time scales (latencies), or eliciting CS’s.Rescorla-Wagner TheoryThere is a maximum associative strength between CS and UCS.UCS determines the limitStrength gained on each training trial depends on prior training.More learning early, less later onRate of conditioning varies.Conditioning of a CS depends on prior conditioning to other stimuli.UCS Preexposure EffectIf the UCS is encountered without the CS prior to pairing of the two, less learning occurs.UCS becomes associated with other environmental stimuli (without CS).Since there is a limit to association strength, some is drained off by such prior associations.CS-UCS association is weakened.Problems with Rescorla-WagnerOvershadowing – salient cues have more associative strength.Sometimes a salient cue potentiates another cue instead of overshadowing.Garcia says cues are indexed.R-W says cues are seen as unitary stimulus.Unclear which explanation is correct.More ProblemsCS preexposure effect – appearance of CS without UCS prior to learning weakens learning.Shouldn’t have any effect according to Rescorla-Wagner theory, but it does.Cue-deflation effect – extinction of a more salient cue enhances learning for the less salient cue.Should be no change according to R-W.Comparator TheoryIf two CS’s are associated, extinction of one should reduce responding to the other.Sometimes true, other times not.CS-UCS associations exist for many stimuli but are exhibited only for the strongest.CS’s are judged in relation to each other.Attentional ViewMackintosh – learned irrelevance occurs during preexposure of CS.Animals exposed to a novel stimulus exhibit an orienting response.No orienting with preexposure.Habituation results in failure of conditioning.Pairing of CS/UCS in novel context results in learning.Retrospective ProcessingMost theories assume the level of responding will be constant after learning.Baker & Mercier suggest association can change after learning.Retrospective processing – CS-UCS contingency reevaluated after learning.Backward blocking – support for theorySuggests animals have mental representations, memory for events.Retrospective ProcessingMost theories assume the level of responding will be constant after learning.Baker & Mercier suggest association can change after learning.Retrospective processing – CS-UCS contingency reevaluated after learning.Backward blocking – support for theorySuggests animals have mental representations, memory for events.Operant ConditioningNature of reinforcement:Premack’s probability differential theoryResponse deprivation theoryBehavioral economics:Behavioral allocation – blisspointChoice behavior – Herrnstein’s matching law.Momentary maximization theoryDelay-reduction theoryProbability-Differential TheoryPremack – a reinforcer can be any activity that is more likely to occur than the reinforced
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