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Learning Foundation of Behaviorism Promoted by John B. Watson Psychology… should be an objective science study behavior not mental processes Definition of Learning Learning is an adaptive1 permanent change2 in behavior or behavior potential3 that is produced as a result of prior experience4 1 occasionally maladaptive such as depressed mental set, obsessions 2 not due to fatigue, injury 3 includes tendencies to respond that might not have been tested 4 excludes maturation, disease, instinct Learning Can there be learning that does not result in a change in behavior? Types of Learning Habituation (simple, single stimulus) Associative Learning (simple, passive, external) Cognitive Learning (complex, strategic, internal) Habituation Simplest form of learning Response to repeated stimulus declines across repetitions. Not due to fatigue because response will reoccur if stimulus is changed. non-associative learning as it involves only one stimulus. Associative learning involves two stimuli (one is associated with the other). Association Event 1 Event 2 Sea snail associates splash with a tail shock Seal learns to expect a snack for its show-off behavior Learning to associate two events Associative Learning Classical Conditioning – associating two stimuli, generally one acts as a signal for the other Operant Conditioning – associating a behavior and its consequences Classical Conditioning Two related events: Stimulus 1 Lightning Stimulus 2 Thunder Result after repetition Stimulus We see lightning Response We wince anticipating thunder We learn to associate two stimuli – one signals the other Operant Conditioning We learn to associate a response with its consequence Response: Pushing vending machine button Consequence:Receiving a candy bar Classical or Pavlovian Conditioning Ivan Pavlov 1849-1936 Russian neurophysiologist studied digestive secretions invented Classical Conditioning Classical Conditioning Pavlov’s device for recording salivation Pavlov’s Experiment Before Conditioning UCS (food in mouth) UCR (salivation) During Conditioning Neutral stimulus (tone) No salivation After Conditioning UCS (food in mouth) Neutral stimulus (tone) UCR (salivation) CS (tone) CR (salivation) Classical Conditioning Strong Acquisition (CS+UCS) Extinction (CS alone) Spontaneous recovery of CR Strength of CR Extinction (CS alone) Weak Pause Time Classical Conditioning Unconditioned Stimulus (UCS) stimulus automatically triggers a response food in mouth Unconditioned Response (UCR) unlearned automatic response to unconditioned stimulus you salivate when food is in your mouth “physiological (hard-wired) association” Conditioned Stimulus (CS) neutral stimulus becomes associated with UCS triggers (conditioned) response Conditioned Response (CR) Nearly the automatic response But it is learned, slightly weaker (a bit less salivation in our example) Effect of unreinforced trials (tone without food following it) Classical Conditioning Acquisition the initial stage of learning, during which a response is established and gradually strengthened Extinction diminishing a conditioned response occurs when an unconditioned stimulus does not follow a conditioned stimulus What makes a good signal Classical Conditioning Spontaneous recovery reappearance, after a rest period, of an extinguished conditioned response Generalization tendency for stimuli similar to the conditioned stimulus to evoke similar responses Discrimination the ability to distinguish between a conditioned stimulus and other similar stimuli that do not signal an unconditioned stimulus Generalization: Little Albert Cognitive Development “Never hug and kiss them, never let them sit on your lap. If you must, kiss them once on the forehead when they say good night. Shake hands with them in the morning. Give them a pat on the head if they have made an extraordinarily good job of a difficult task. Try it out. In a week’s time you will find how easy it is to be perfectly objective with your child and at the same time kindly. You will be utterly ashamed at the mawkish, sentimental way you have been handling it.” —John Watson “Psychological Care of Infant and Child” Classical Conditioning Temporal Contiguity was thought to be sufficient – the CS simply needs to occur immediately prior to the UCS for conditioning to take place Equipotentiality: any two stimuli could be associated through conditioning Reliable signal? Informative and contingent Temporal Contiguity is Not Enough Contingency: The CS must reliably predict the occurrence of the UCS (Rescorla, 1966) Informativeness: The CS must provide new information for predicting the occurrence of the UCS Informativeness: Blocking If an organism has already learned that one CS predicts the UCS, that will block the conditioning of a new CS if the new CS does not provide any additional information Example: Fear conditioning of a tone blocks conditioning of a light Blocking Training 1 Training 2 Test -none- Tone & Light, shock (CR = fear) Light Fear Tone, shock (CR = fear) Tone & Light, shock (CR = fear) Light No Fear Classical Conditioning Goes awry Normally neutral stimulus becomes signal of negative CR Nausea Conditioning among Cancer Patients UCS (drug) UCR (nausea) CS (waiting room) UCS (drug) UCR (nausea) CS (waiting room) CR (nausea) Classical Conditioning Drug Tolerance Example Drug Tolerance Drugs have less of an effect when taken repeatedly (less of a high) Drug users crave more of the drug despite its lessening effects Certain drugs trigger our body to call upon its defenses against the effects of the drug (parasympathetic or shutdown system) Siegel (1977, 1983) Demonstrated that classical conditioning principles might be in effect during druginjecting episodes… Possible reason for overdoses Siegel (1977, 1983) UCS ---------------------------------------------- UCR (drug) (anti-drug defenses) CS ----------------------------------------------- NO RESPONSE (injection ritual) (no defenses) CS + UCS -------------------------------------- UCR (injection ritual) + (drug) (anti-drug defenses) * Repeated several times CS ----------------------------------------------- CR (injection ritual) (anti-drug defenses) Siegel (1977, 1983) Familiar setting-------------------- anti-drug defenses (usual time, place, etc) (body reacts) New setting ---------------------------- no defenses (place, time are different) (body doesn't react) Same dosage becomes an overdose – they get too high as their bodies have been fooled by the new procedure, no signals to start dampening down of response Atkinson, Krank, and McCully (1982) Lab rats preconditioned to tolerate large doses of heroin… Trial 1……….Room 1…………….Saline………Rats okay Trial 1……….Room 1…………….Drug……….Rats get high Trials 2-19 are identical to Trial 1… Trial 20…….Room 2…………….Saline………Rats okay Trial 20…… Room 2…………….Drug………..Rats die Atkinson, Krank, and McCully (1982) Results: >50% increase in death rate in new room Rats show "room-specific" tolerance May explain overdoses in humans Practical implications as far as detoxification is concerned (returning clean addict to street, friends) Operant Conditioning Law of Effect (Thorndike) Rewarded behavior is repeated Operant Conditioning behavior strengthened if followed by reinforcement behavior weakened if followed by punishment Trial-and-error learning A cat’s Behavioral Repertoire (here, for escaping an enclosed space) Operant Conditioning Operant Behavior voluntary behaviors operates [acts] on environment Behavior Consequences Reinforcer any event that follows behavior AND strengthens it Operant Conditioning B.F. Skinner (19041990) Built on Thorndike’s Law of Effect Discovered schedules of reinforcement Operant Conditioning Operant Chamber (“Skinner Box”) chamber with a bar that an animal can press to obtain a food reinforcer Frequency of responses are recorded Principles of Reinforcement Primary Reinforcer innate reinforcer, satisfies biological need e.g., food, water, warmth Secondary Reinforcer conditioned reinforcer, gains its reinforcing power through association with primary reinforcer e.g., money Schedules of Reinforcement Continuous Reinforcement reinforcing the desired response each time it occurs learning occurs rapidly extinction occurs rapidly Partial Reinforcement reinforcing a response only part of the time learning occurs slowly resistance to extinction Schedules of Reinforcement Number of responses 1000 Fixed Ratio Variable Ratio Fixed Interval 750 Rapid responding near time for reinforcement 500 Variable Interval 250 Steady responding 0 10 20 30 40 50 Time (minutes) 60 70 80 Schedules of Reinforcement Fixed Ratio (FR) behavior is reinforced only after the behavior occurs a specified number of times the faster you respond, the more rewards you get! different ratios very high rate of responding like piecework pay Schedules of Reinforcement Variable Ratio (VR) behavior is reinforced after an unpredictable number of times like gambling, fishing very hard to extinguish because of unpredictability Schedules of Reinforcement Fixed Interval (FI) behavior is reinforced only after a specified time has elapsed frequency of behavior increases when the time for reward draws near Schedules of Reinforcement Variable Interval (VI) behavior is reinforced at unpredictable time intervals produces slow, steady responding like pop quiz! Reinforcement Schedule examples Buying a lottery ticket and winning vr Watching & seeing a shooting star vi Receiving allowance Saturday for having clean room fi Hotel maid gets 15-min break after cleaning four rooms fr Discrimination Demo $1 for getting right answer, owe $1 for wrong + Mother - Son Father Sister Friend (triangle) Uncle Shaping Can leave lab once rat touches lever three times in 10 seconds Shaping Successive approximations to goal behavior Punishment An aversive event that decreases the behavior that it follows Reinforcement & Punishment Positive reinforcement Negative reinforcement Positive punishment Negative punishment Operant Conditioning Appetitive Presented Positive reinforcement Positive event follows response e.g. reward Removed Punishment Positive state removed after response e.g. time-out or omission training Aversive Punishment Discomfort follows response e.g. punishment Negative reinforcement Discomfort removed after response e.g. escape or avoidance learning Positive & negative reinforcement Positive & negative punishment Problems with Punishment Punished behavior is not forgotten, it's merely suppressed behavior returns when punishment removed Causes increased aggression Creates fear That may generalize to undesirable behaviors, e.g., fear of school Does not necessarily guide toward desired behavior reinforcement tells you what to do punishment tells you what not to do Punishment teaches you mostly how to avoid it Operant vs Classical Conditioning Comparison of Classical and Operant Conditioning Classical Conditioning Operant Conditioning The response Involuntary, automatic “Voluntary,” operates on environment Acquisition Associate events; CS signals UCS Associate response with a consequence (reinforcer or punisher). Extinction CR decreases when CS is repeatedly presented alone. Responding decreases when reinforcement stops. Cognitive processes Subjects develop expectation that CS signals the arrival of UCS Subjects develop expectation that a response will be reinforced or punished; they also exhibit latent learning, without reinforcement. Biological Natural predispositions constrain predispositions which stimuli-responses can easily be associated. Organisms best learn behavior similar to their natural behaviors; unnatural behaviors instinctively drift back toward natural ones. Behaviorism cannot explain: Latent Learning – learning without reinforcement (Tolman & Honzig, 1930) Observational Learning – learning without behaving or being reinforced directly (Bandura, 1977) Overjustification – when rewards decrease the frequency of behavior Language Acquisition – Chomsky’s critique marked the end of behaviorism as the dominant paradigm of psychology Latent Learning: learning that occurs but is not apparent until there is a reinforcer to demonstrate it Group 1: no food reward Group 2: always food reward Group 3: food after 10 days Behaviorism cannot explain: Latent Learning – learning without reinforcement (Tolman & Honzig, 1930) Observational Learning – learning without behaving or being reinforced directly (Bandura, 1977) Overjustification – when rewards decrease the frequency of behavior Language Acquisition – Chomsky’s critique marked the end of behaviorism as the dominant paradigm of psychology Observational Learning Bobo Doll study (Bandura) Behaviorism cannot explain: Latent Learning – learning without reinforcement (Tolman & Honzig, 1930) Observational Learning – learning without behaving or being reinforced directly (Bandura, 1977) Overjustification – when rewards decrease the frequency of behavior Language Acquisition – Chomsky’s critique marked the end of behaviorism as the dominant paradigm of psychology Language acquisition Chomsky: Association is insufficient to explain language learning. We acquire RULES of language, not instances Evidence: Over-regularization (“goed”) Conclusion: Mere associations between words cannot explain language Behaviorism lacks Symbolic Representation – we have (internal) representations for things in the world Structure – we learn sets of rules for combining symbols (e. g., grammar), not mere associations between pairs of symbols Lead to Cognitive paradigm in psychology Is brain-behavior behavior? If so, it can be conditioned just like other behaviors Two current fields: Neurotherapy and Brain-Computer interfaces (BCI) Electrical stimulation of brains (ESB) Electrical stimulation of brains of rats James Olds in 1950s; Jacobsen and Torkildsen replicated work in humans; some epileptics stimulated themselves into convulsions INTRA-CRANIAL SELFSTIMULATION Rodent wireheads 0.0005 amperes for less than a second whenever rat pushed lever Rates of up to 10,000 bar-presses an hour recorded Medial forebrain bundle passing through lateral hypothalamus and ventral tegmentum An animal will self-stimulate for more than 24 hrs continuously without rest, and will cross electrified grid to gain access to lever Other brain centers are aversive, such as periaqueductal grey matter (PAG) Ventral tegmental area (VTA) neurons manufacture dopamine and they are under continuous inhibition by gammaaminobutyric acid (GABA) system, an important component of the ”final common pathway" of reward, implicated in addiction, mood, and learning. Biofeedback Neal E Miller trained autonomic functions Rats control heartrate to get water Dogs salivate to get food +/- together leads to organism shutdown (internal inhibition) Pavlov conditioning experiments Tone for food, buzzer for shock – Moved them closer together in time confounded dog fell asleep Termed “internal inhibition” Animal can close down own systems to avoid stress Two forms of Biofeedback: PNS & CNS (peripheral and central) Peripheral: Body (skin) temperature, GSR (skin conductance), muscle (EMG), heart rate variability, breathing, pulse CNS: Central Nervous System biofeedback When you become aware of your own brain activity–you can change it