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Classical conditioning

Classical conditioning

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Classical conditioning

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  1. Classical conditioning Sensitization, habituation, pseudoconditioning, and background conditioning S-S vs S-R theories...or is it something else?

  2. Classical conditioning phenomena • Human conditioning studies • Eyeblink conditioning • Lemon-drop salivation conditioning • Little Albert • Typical acquisition and extinction curves • Optimal CS-US intervals are 200 – 700 ms • GSR conditioning has a 3 – 5 second interval

  3. (CS) Sensitization • In typical classical conditioning experiments, CS reliably precedes US: Contingency exists. • If contingency is not present, people will still come to respond to the CS as they experience the US: Sensitization. • Thus, sensitization to repeated presentations of the CS will produce responses that only look like conditioned responses. • Sensitization also occurs to repeated presentation of strong USs.

  4. Assessing sensitization • Compare two experimental conditions (groups) to see if response is a CR or a sensitization response. • Condition 1: CS reliably predicts US • Condition 2: CS occurs just as frequently, but does not reliably predict US • Could the Little Albert results be explained as sensitization? Was there a control condition? • Could sensitization explain why some students prefer to study with music playing?

  5. Habituation • UR magnitude decreases as US is presented repeatedly. • Habituation is less likely with stronger USs • Both sensitization and habituation show learning has taken place, but it is nonassociative learning. • Both may interfere with associative learning.

  6. Sniffy details • Sniffy is programmed to habituate to low-intensity shock USs, to sensitize to high-intensity shock USs, and to remain stable under moderate-intensity shock USs. • Sniffy output includes • Pain (mid-level unless sensitizing or habituating) • Fear, a result of conditioning or US presentation • CS response strength to various CSs, including the background (cage) • Movement ratio, measuring classical conditioning of fear • Suppression ratio, measuring effect on operant responding • The cumulative record of stimulus presentation and bar-press responses. Ignore this until we start operant conditioning.

  7. (US) Pseudoconditioning • Repeated presentations of a US may increase the likelihood of responding (with the UR) to any novel stimulus, even if it is not paired with the US as a CS. • Little Albert’s apparent conditioning to the rat CS may have been an artefact of the repeated loud noise US: pseudoconditioning.

  8. Assessing pseudoconditioning • Kimble, Mann & Dufort (1955): Human eyeblink conditioning • Group 1: 60 paired trials of light CS with airpuff US • Group 2: 20 paired trials, 20 US-only trials, 20 paired trials • Response patterns were the same in the last 20 trials. • The result cannot be due to associative learning in the middle 20 trials. • Test pseudoconditioning with unpaired control.

  9. Background conditioning • When the US is too strong to habituate, the US may become associated with the context or background of the learning situation. • Thus, in background conditioning, the individual associates the shock with the setting, such as the conditioning chamber.

  10. Conditioned inhibition • Inhibition develops in extinction (Pavlov) • Reactive inhibition (Hull) develops in repeated responding • Inhibition may be conditioned (Pavlov) • Training: • CS1(metronome)  US(food) • CS1(metronome) + CS2 (whistle)  No US

  11. Testing conditioned inhibition • CS1 (metronome)  CR(salivation) • CS1(metronome) + CS2(whistle)  No CR • Then, the summation test: • Train with a new CS: • CS3(touch nose) US(food) • Test response to CS2 + CS3? • Less responding: Conditioned inhibition.

  12. Classical conditioning theory • Watch Pavlov’s experiments. • If conditioning does involve association, what is being associated? • CS and US? • CS and UR/CR? • Is the learning S – S or S – R?

  13. S-S vs . S-R theories: What is associated? • Response prevention • Learning phase: CS + US  no UR • Testing phase: CS  CR • US devaluation • Learning phase: CS + US  CR/UR • Next, devalue the US through satiation • Test phase: CS  lessened CR

  14. Classical conditioning theory • S-S or S-R theories, continued: • Sensory preconditioning • Preconditioning phase: CS1 + CS2 OR • Conditioning phase: CS1 + US  UR • Test phase: CS1 CR. • CS2 ? • Response-prevention, US devaluation, and sensory preconditioning support S - S theory

  15. S - S or S - R ? • Second-order conditioning • Start with standard pairing of CS1 and US • CS1 CR • Then pair CS1 + CS2 • Test: CS2  CR • Then devalue US, or extinguish CS1 • Test: CS2 CR • Whether CS connects to US or CR depends on which is more salient

  16. A crucial test • Set up a second-order conditioning experiment: • CS1(light) + US1 (food)  UR1(salivation) • Test: CS1 (light)  CR1 (salivation) • CS2(buzzer) + CS1(light)  CR1(salivation) • Test: CS2 (buzzer)  CR1 (salivation) • Then: CS1 (light) + US2(shock)  UR2(leg lift) (Counterconditioning) • Test: CS2 CR1

  17. Changing representations • Covert conditioning • Autoshaping: Light + Food  Key peck • But start with Tone + Food  No key peck • Pair Tone + light in 2nd order conditioning • Autoshaping occurs • Supports S-S • US devaluation also shows changing representations.

  18. One more second-order experiment • First autoshape all pigeons to peck at a lighted key CS1, which is sometimes red, sometimes yellow. • CR is the key peck. • Add CS2 of either vertical or horizontal lines on lighted key. • One group then has simple CS1-CS2 pairings (red-vertical and yellow-horizontal), while the other group has complex pairings (sometimes red-vertical, sometimes red-horizontal, etc.). • Thus, group 1 has two trial types, and group 2 has four trial types. • S-S theory thus predicts better learning for group 1. • That is what happens.

  19. Pavlov’s studies • This video clip, a reenactment, shows Pavlov’s methods for • Measurement of UR and the salivary reflex • Discovery of classical conditioning • Testing different CSs