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  1. Learning • Foundation of Behaviorism • Promoted by John B. Watson • Psychology… • should be an objective science • study behavior not mental processes

  2. 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

  3. 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)

  4. 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).

  5. Association • Learning to associate two events Event 1 Event 2 Sea snail associates splash with a tail shock Seal learns to expect a snack for its show-off behavior

  6. Associative Learning • Classical Conditioning – associating two stimuli, generally one acts as a signal for the other • Operant Conditioning – associating a behavior and its consequences

  7. Two related events: Stimulus 1 Lightning Stimulus 2 Thunder Result after repetition Stimulus We see lightning Response We wince anticipating thunder Classical Conditioning • We learn to associate two stimuli – one signals the other

  8. Response: Pushing vending machine button Consequence:Receiving a candy bar Operant Conditioning • We learn to associate a response with its consequence

  9. Classical or Pavlovian Conditioning • Ivan Pavlov • 1849-1936 • Russian neurophysiologist • studied digestive secretions • invented Classical Conditioning

  10. Classical Conditioning • Pavlov’s device for recording salivation

  11. Before Conditioning UCS (food in mouth) Neutral stimulus (tone) UCR (salivation) No salivation During Conditioning After Conditioning UCS (food in mouth) CS (tone) Neutral stimulus (tone) UCR (salivation) CR (salivation) Pavlov’s Experiment

  12. Acquisition (CS+UCS) Strong Spontaneous recovery of CR Extinction (CS alone) Strength of CR Extinction (CS alone) Weak Pause Time Classical Conditioning

  13. 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) Classical Conditioning

  14. Effect of unreinforced trials (tone without food following it)

  15. 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

  16. What makes a good signal

  17. 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

  18. Generalization:Little Albert

  19. 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”

  20. 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

  21. Reliable signal? Informative and contingent

  22. 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

  23. 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

  24. Blocking

  25. Classical Conditioning • Goes awry • Normally neutral stimulus becomes signal of negative CR

  26. UCS (drug) UCR (nausea) CS (waiting room) UCS (drug) UCR (nausea) CS (waiting room) CR (nausea) Nausea Conditioning among Cancer Patients

  27. 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)

  28. Siegel (1977, 1983) • Demonstrated that classical conditioning principles might be in effect during drug-injecting episodes… • Possible reason for overdoses

  29. 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)

  30. 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

  31. 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

  32. 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)

  33. Operant Conditioning • Law of Effect (Thorndike) • Rewarded behavior is repeated • Operant Conditioning • behavior strengthened if followed by reinforcement • behavior weakened if followed by punishment

  34. Trial-and-error learning

  35. A cat’s Behavioral Repertoire (here, for escaping an enclosed space)

  36. Operant Conditioning • Operant Behavior • voluntary behaviors • operates [acts] on environment • Behavior  Consequences • Reinforcer • any event that follows behavior AND strengthens it

  37. Operant Conditioning • B.F. Skinner (1904-1990) • Built on Thorndike’s Law of Effect • Discovered schedules of reinforcement

  38. 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

  39. 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

  40. 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

  41. Number of responses Fixed Ratio 1000 Variable Ratio Fixed Interval 750 Rapid responding near time for reinforcement 500 Variable Interval 250 Steady responding 0 10 20 30 40 50 60 70 80 Time (minutes) Schedules of Reinforcement

  42. 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

  43. 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

  44. 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

  45. Schedules of Reinforcement • Variable Interval (VI) • behavior is reinforced at unpredictable time intervals • produces slow, steady responding • like pop quiz!