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Chapter 6

Chapter 6. Learning and Behavior. Learning. A more or less permanent change in behavior that results from experience. Behavior. The ways in which animals act or respond in an environment influenced by both biological and learned components. Richard Dawkins: Memes.

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Chapter 6

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  1. Chapter 6 Learning and Behavior

  2. Learning • A more or less permanent change in behavior that results from experience

  3. Behavior • The ways in which animals act or respond in an environment • influenced by both biological and learned components

  4. Richard Dawkins: Memes • A cultural invention that is passed on from one generation to the next • Marvin Harris (1974) • “Our primary mode of biological adaptation is cultural not anatomical”

  5. Ivan Pavlov • Learning is an associative process • Pavlov studied a learned association between a neutral stimulus and a reflexive response

  6. Classical Conditioning • US - Unconditioned Stimulus • stimulus that evokes the behavioral response of interest (Meat powder) • UR - Unconditioned Response • the reflexive response to the presentation of the US (Salivation) • NS - Neutral Stimulus • a stimulus that does not result in an unconditioned response (Bell)

  7. produces produces Classical Conditioning Before Conditioning No UR (No Salivation) NS (Bell)

  8. No UR (No Salivation) NS (Bell) produces produces produces produces Classical Conditioning Before Conditioning US (Meat) UR (Salivation)

  9. produces produces Classical Conditioning During Conditioning Trial 1 NS (Bell) + US (Meat) UR (Salivation) +

  10. produces produces Classical Conditioning During Conditioning Trial 2 NS (Bell) + US (Meat) UR (Salivation) +

  11. produces produces Classical Conditioning During Conditioning Trial 3 NS (Bell) + US (Meat) UR (Salivation) +

  12. produces produces Classical Conditioning During Conditioning Trial 4 NS (Bell) + US (Meat) UR (Salivation) +

  13. produces produces Classical Conditioning After Conditioning CS (Bell) CR (Salivation)

  14. Classical Conditioning • CS - Conditioned Stimulus (Bell) • what used to be called the neutral stimulus. • Initially it evoked no response, but, after conditioning, it now evokes a response • CR - Conditioned Response (Salivation) • similar (but often not identical to) the unconditioned response • but is evoked by the conditioned stimulus

  15. Habituation and Sensitization • Can animals learn without association? • Habituation • Decreased responsiveness to repeated stimulation • Sensitization • Increased responsiveness following a single stimulus presentation

  16. Extinction • A reduction in the conditioned response when the conditioned stimulus is presented without the unconditioned stimulus • e.g. presenting the bell repeatedly without the meat will eventually eliminate the salivation

  17. Spontaneous Recovery • The reappearance of the conditioned responses following a delay in the extinction process

  18. 24 Hour Delay Extinction Bell Only Spontaneous Recovery Bell Only Acquisition Bell+Meat CR: Drops of Saliva Trials

  19. Higher Order Conditioning • First Order Conditioning: • Associating Bell + Meat Powder eventually leads to salivation to Bell alone (Bell = CS1) • Higher Order Conditioning • Associate CS1 with a new CS (e.g. Light) • Associating Bell + Light eventually leads to salivation to Light alone (Light = CS2)

  20. produces produces Higher Order Conditioning During Conditioning CS1 (Bell) + NS (Light) CR (Salivation) +

  21. produces produces Higher Order Conditioning After Conditioning CS2 (Light) CR (Salivation) Important: The Light is never directly associated with meat

  22. Basic Rules of Conditioning • The more association trials, the better the conditioning • CS and US must be closely linked in time • Physically intense stimuli are conditioned more easily • Some things are more easily conditioned than others

  23. Stimulus Generalizationand Discrimination • Stimulus Generalization • Animals will show a Conditioned Response to stimuli similar to the original CS

  24. Stimulus Generalizationand Discrimination • Discrimination • If you repeatedly associate one CS with the US and do not associate the second, the CR will discriminate the two CS+ CS-

  25. Figure 6.4

  26. Real-Life Examplesof Classical Conditioning • Conditioning Emotional Responses • Baby Albert (Watson and Rayner, 1920) • Conditioned fear to a white rat by associating a loud noise with the rat • CS = rat • US = loud noise • UR = startle to loud noise • CR = startle to rat

  27. Real-Life Examplesof Classical Conditioning • Learning the meaning of words • Word is associated with the sensory impression • e.g. “apple” and view of an apple • “Second-signal system”

  28. Real-Life Examplesof Classical Conditioning • Conditioned Taste Aversion • a taste (CS) associated with a toxin (US) leads to nausea (UR) • later, the taste alone evokes nausea (CR)

  29. Real-Life Examplesof Classical Conditioning • Drug Tolerance • drug users become increasingly less responsive to the effects of the drug • tolerance is specific to specific environments (e.g. bedroom) • familiar environment becomes associated with a compensatory response • taking drug in unfamiliar environment leads to lack of tolerance

  30. Instrumental Learning • Pavlov • Classical conditioning of reflexes • Can learning occur with nonreflexive behavior? • Instrumental Response: a voluntary response that acts on the environment in a meaningful way

  31. Instrumental Learning • The modification of instrumental responses using reinforcers and punishers

  32. E.L. Thorndike’s Puzzle Box • Cat placed in a box that can be opened from inside by pushing on latch • Initially, cat shows random behaviors • scratching • sniffing • Eventually cat will hit latch • hitting latch leads to pleasant consequence - escape • increases likelihood action will occur again

  33. Thorndike’s Law of Effect • Responses followed by “satisfiers” tend to be repeated • Those followed by “annoyers” are not repeated • useful behaviors are stamped in

  34. Operants • B.F. Skinner: • An operant is an instrumental response that operates on the environment • Positive Reinforcer • Any stimulus that increases the likelihood of an operant response • Skinner developed a general model of learning called “operant conditioning”

  35. The Operant Chamber

  36. Shaping Behavior • Reinforce responses that approximate the target behavior

  37. Secondary Reinforcement • Neutral stimuli can acquire reinforcing properties through the process of higher-order conditioning • e.g. the reinforcing effect of language (“good boy”)

  38. Schedules of Reinforcement • Rate at which reinforcer is delivered influences nature of response • Continuous reinforcer • each response is reinforced • Partial Reinforcement • reinforcer is not delivered for each response

  39. Partial Reinforcement • Fixed Ratio (FR) Schedule • reinforcer is delivered only after a fixed number of responses have been made • e.g. FR-10 schedule: reinforcer delivered after every 10th lever press

  40. Partial Reinforcement • Variable Ratio (VR) Schedule • the number of responses before a reinforcer is delivered varies

  41. Partial Reinforcement • Fixed Interval (FI) Schedule • the first response following a specified time interval is reinforced • e.g. FI-10 schedule: only responses made after 10 seconds are reinforced

  42. Partial Reinforcement • Variable Interval (VI) Schedule • the first response following a varying time interval is reinforced

  43. Partial Reinforcement affects Response Rate

  44. Partial Reinforcement Effect • If you train an animal using partial reinforcement, it is more resistant to extinction than one that received continuous reinforcement • Extinction • a reduction in the rate of response when a reinforcer is withheld

  45. Differential Reinforcement • Differential Reinforcement of a High Rate of Response (DRH) • reinforce bursts of responses • Differential Reinforcement of a Low Rate of Response (DRL) • reinforce pauses between responses

  46. Behavioral Control • Skinner: • The likelihood of any behavior depends on reinforcement and punishment contingencies • Environmental Determinism • environmental stimuli exert total control over behavior

  47. Stimulus Control • The Discriminative Stimulus (Sd) • a signal that indicates when a response will be reinforced • e.g. reinforcing lever pressing only when light is on • Negative Discriminative Stimulus (S) • A signal that indicates that a response will not be followed by reinforcement

  48. Stimulus Control • Responding only in the presence of Sd and not in the presence of S

  49. Punishment • Another potential consequence of behavior • An aversive stimulus that decrease the rate of responding • When is punishment most effective? • It must be relatively intense • It must follow the response relative quickly • It must be applied consistently

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