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Inhibitory Pavlovian Conditioning

Inhibitory Pavlovian Conditioning. Stimuli can become conditioned to signal the absence of a US— such learning is called Inhibitory Conditioning CS+ = excitatory CS = CS US CS- = inhibitory CS = CS no US. Inhibitory Conditioning only occurs if there is an

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Inhibitory Pavlovian Conditioning

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  1. Inhibitory Pavlovian Conditioning Stimuli can become conditioned to signal the absence of a US— such learning is called Inhibitory Conditioning CS+ = excitatory CS = CS US CS- = inhibitory CS = CS no US Inhibitory Conditioning only occurs if there is an excitatory context

  2. Procedures for Inhibitory Conditioning Conditional (standard) • On some trials: • CS+1US • On other trials: • CS+/CS-1 no US • Whether the CS+ is followed by the US is conditional on the presence of the CS-.

  3. Explicitly unpaired/Negative contingency p(US/CS-) < p(US/no CS) • On some trials: • US alone • On other trials: • CS- alone • The CS- occurs on different trials than the US, which is not signalled by a specific CS+.

  4. Differential procedure • On some trials: • CS+1US • On other trials: • CS-1 no US • The CS- occurs on different trials than the CS+ and US. • The background cues provide the excitatory context

  5. Backward conditioning US 1 CS If the US comes on before the CS, then the CS actually signals the absence of the US (because the US has already happened).

  6. Trace or Long-Delay conditioning CS US The CS comes on but there is a long interval before the US is delivered. The CS essentially signals a period when the US is absent

  7. Measuring Conditioned Inhibition Once an animal learns that a stimulus signals the absence of the US, what does it do with this information? What is the behavior? With excitatory conditioning, the CS comes to elicit certain behaviors (i.e., salivation, eyeblink, keypecking) The identification of a conditioned inhibitory response can be more difficult

  8. Measuring Conditioned Inhibition • Directed Behavior Test • Summation Test • Retardation of Acquisition Test

  9. Directed Behavior Test • Sometimes inhibition can be measured directly by just presenting the CS- • but only if conditioned behavior varies above and below a baseline level (e.g., heart rate, blood pressure, temperature). • If CS+/US resulted in increase in behavior, inhibition would be evident if the behavior decreased on presentation of CS-. • Subjects can also approach a CS+ and avoid a CS-

  10. If the CR is not bidirectional, Summation (or Compound Stimulus) Test present the CS- in combination with a new CS+ that signals the US conditioned inhibition is indicated if the CR to CS+ is less when CS- is present than when CS+ is presented alone.

  11. Summation Test (Cole, Barnet, & Miller, 1997) Training: On some trials: Light Shock On other trials: Light + Noise No Shock On yet other trials: Clicker Shock Test: The time it took the rats to complete 5 seconds of drinking was measured in the presence of: ►the light (conditioned excitor) ►the clicker (conditioned excitor) ►the light + noise (conditioned inhibitor) ►the clicker + noise (conditioned inhibitor)

  12. Results: Light = conditioned excitor Clicker = conditioned excitor Noise = conditioned inhibitor Clicker Clicker & Noise Clicker & Buzzer Light & Noise Light Text p.85

  13. The important test was Clicker alone vs Clicker + Noise The rats feared the clicker alone (the rats took longer to drink), but the presence of the noise (which had signalled no shock when paired with the light and had never been paired with the clicker) reduced the fear elicited by the clicker. The excitatory effect of the clicker (expect shock; fear) and the inhibitory effect of the noise (do not expect shock; reduced fear) summate, and produce a reduced conditioned fear response.

  14. Retardation-of-Acquisition Test If the CS- is a conditioned inhibitor for a particular US, it should: • Be harder than a neutral stimulus to turn into a conditioned excitor (i.e., a CS+) That is, learning that the stimulus now predicts the US should be retarded relative to controls that did not have the CS previously conditioned as an inhibitor.

  15. Example of Retardation of Acquisition Test Conditioned Inhibition Group On some trials: Light Shock No Shock On other trials: Light + Noise Control Group Light Shock On a test: All groups get Noise Shock

  16. Compare strength of conditioning for conditioned inhibition and control groups Conditioned Inhibition Group should take longer to acquire a CR than the Control Group.

  17. Lick Suppression Test

  18. Comparison of CE and CI Excitation is quicker and easier to get than inhibitory conditioning -US is a more salient event than no-US Extinction is different with CS+ versus CS- -can’t simply give CS by itself

  19. What can reduce/extinguish a CI? -presentation of the US -even if given randomly; not necessary to have CS-US pairings -change from a negative contingency to a ‘0’ contingency (i.e., no predictive relationship)

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