Mechanisms of Conditioning: Flavor Aversion Learning

1. PSY 402 Theories of Learning Chapter 3 – Nuts and Bolts of Conditioning (Mechanisms of Classical Conditioning)

2. Flavor Aversion Learning • Garcia – rats will not drink water with saccharin if they get ill after drinking. • Significant avoidance occurs after just one trial. • Human food aversions are related to illness (89%). • Even if illness occurs hours later it is linked to the previous meal. • Not cognitive – you can know the food is not to blame and still feel an aversion to it.

3. Factors Affecting Conditioning • Timing – how closely in time are the CS and UCS, and which occurs first. • Novelty of the CS and UCS. • Intensity (strength) of the CS and UCS. • Consistency of the pairing between the CS and UCS. • If one or the other appears alone then conditioning is weakened.

4. Stimulus Presentation Paradigms • Delayed conditioning – the CS onset precedes the UCS onset. • Trace conditioning – the CS starts and ends before the UCS onset. • Simultaneous conditioning – the CS and UCS occur together. • Backward conditioning – the UCS starts and ends before the CS onset. • These paradigms will be on the midterm

5. 3.8 Different ways to present CS and US in time This works best The longer the gap (trace interval) the worse this works This isn’t as good as delayed This doesn’t work at all

6. Massed vs Spaced Trials • Better learning occurs when trials are spaced out over time (spaced), rather than bunched together (massed). • Memory consolidation or rehearsal may be needed between trials. • The ratio between the exposure to the CS and the time in-between is the important factor. • If both are the same duration, learning is weaker.

7. 3.9 Trial spacing in Pavlovian conditioning This works best This doesn’t work as well

8. Importance of Novelty • Preexposure to the CS (before it is paired with the UCS) reduces learning. • Called latent inhibition because it inhibits learning of the CS-UCS association. • The same thing happens with preexposure to the US (before it is paired with the CS). • Called the US preexposure effect • Other, more novel stimuli are more likely to become associated with the UCS.

9. Stimulus Intensity (Strength) • The stronger the US (UCS), the faster the learning and the stronger the association. • The stronger the CS, the better the learning. • Salience – how attention-getting the stimulus is in relation to other stimuli in the environment. • The most salient CS becomes associated with the UCS. • An overpowering CS may elicit a response of its own, preventing learning.

10. Pseudo-conditioning • Responses to the CS may occur due to the strength of the UCS, not learning. • Once air has been puffed at the eye, blinking may occur in response to any stimulus that comes next, without any learning. • Sensitization resulting from an intense UCS may cause the response to a CS to be increased, even when there is not greater learning. • A control group lets you tell the difference.

11. 3.10 Bernstein’s experiment on taste aversion learning

12. Acquired Changes in Response • Habituation – response to a repeated stimulus decreases with non-threat experience. • Sensitization – response to a variety of stimuli increases with a single threat experience. • Examples: • Ingestional neophobia, fear of new food • Rats orient less toward light, startle decreases • Chicks are less frightened by shadows flying overhead with repeated exposure.

13. Factors Affecting Conditioning • Timing – how closely in time are the CS and UCS, and which occurs first. • Novelty of the CS and UCS. • Intensity (strength) of the CS and UCS. • Consistency of the pairing between the CS and UCS. • If one or the other appears alone then conditioning is weakened.

14. Stimulus Presentation Paradigms • Delayed conditioning – the CS onset precedes the UCS onset. • Trace conditioning – the CS starts and ends before the UCS onset. • Simultaneous conditioning – the CS and UCS occur together. • Backward conditioning – the UCS starts and ends before the CS onset. • These paradigms will be on the midterm

15. 3.8 Different ways to present CS and US in time This works best The longer the gap (trace interval) the worse this works This isn’t as good as delayed This doesn’t work at all

16. Massed vs Spaced Trials • Better learning occurs when trials are spaced out over time (spaced), rather than bunched together (massed). • Memory consolidation or rehearsal may be needed between trials. • The ratio between the exposure to the CS and the time in-between is the important factor. • If both are the same duration, learning is weaker.

17. 3.9 Trial spacing in Pavlovian conditioning This works best This doesn’t work as well

18. Importance of Novelty • Preexposure to the CS (before it is paired with the UCS) reduces learning. • Called latent inhibition because it inhibits learning of the CS-UCS association. • The same thing happens with preexposure to the US (before it is paired with the CS). • Called the US preexposure effect • Other, more novel stimuli are more likely to become associated with the UCS.

19. Stimulus Intensity (Strength) • The stronger the US (UCS), the faster the learning and the stronger the association. • The stronger the CS, the better the learning. • Salience – how attention-getting the stimulus is in relation to other stimuli in the environment. • The most salient CS becomes associated with the UCS. • An overpowering CS may elicit a response of its own, preventing learning.

20. Pseudo-conditioning • Responses to the CS may occur due to the strength of the UCS, not learning. • Once air has been puffed at the eye, blinking may occur in response to any stimulus that comes next, without any learning. • Sensitization resulting from an intense UCS may cause the response to a CS to be increased, even when there is not greater learning. • A control group lets you tell the difference.

21. 3.10 Bernstein’s experiment on taste aversion learning

22. Conditioned Inhibition • A CS can signal the presence of a UCS. • This is called excitation, CS+ • A CS that never appears with the UCS signals the absence of the UCS. It becomes an “all clear” signal. • This is called inhibition, CS- • In fear conditioning an excitor produces anxiety, an inhibitor produces relief or safety.

23. Detection of Conditioned Inhibition • Summation test: • Step 1 – Condition two stimuli as CS+ & CS- • Step 2 – Present both together. • Step 3 – Present the CS+ alone, with a neutral stimulus, or with another CS+. • The results of Step 2 should be less than Step 3. • Retardation of Acquisition test – turning a CS- into a CS+ takes longer than creating a CS+ from a neutral stimulus.

24. 3.11 Hypothetical effects of an excitor alone, with an inhibitor, and with another excitor

25. 3.12 Hypothetical effects of pairing an inhibitor with a US

26. Producing Conditioned Inhibition • Differential (discriminative) inhibition: • Present two stimuli, one always with the UCS, the other always without the UCS. • Conditioned inhibition procedure: • Present the CS with the UCS sometimes, but pair the CS with another stimulus (X) when the UCS is not present. The CS-X combination will produce inhibition. • CS-X is called a compound CS

27. More Inhibition Procedures • Explicitly unpaired (negative correlation): • The CS and UCS never appear together. • Backward conditioning is a type of negative correlation because the CS always appears after the UCS. • Inhibition of delay – when the CS is lengthy (e.g., a very long tone or light), the CR will occur closer in time to the UCS with practice.

28. Necessary Conditions for Inhibition • The CS must occur without a UCS in a situation where a UCS is possible – when it is otherwise expected. • The CS then becomes a signal of the absence of the UCS. • The CS is irrelevant and no attention is paid to it if there is no relation (contingency) between it and the UCS.

29. 3.13 Rescorla’s experiments: CS-US contingency in conditioning

30. Blocking and Unblocking • Blocking studies what happens when there are two CS’s and a single UCS. • When two neutral stimuli are paired with a UCS, one becomes a CS associated with the UCS and the other does not – it is blocked. • The unattended stimulus is blocked because it provides no new information about the UCS. • When it provides info about intensity it is unblocked.

31. 3.14 (A) Design and; (B) Results of Kamin’s blocking experiment More learning

32. 3.15 (A) Design and; (B) Results of Kamin’s unblocking experiment For group 2, L is paired with the larger shock.

33. Relative Validity • In a situation where differential stimuli vary with the presence of the UCS but a third stimulus does not, blocking occurs (correlated condition). • In a situation where all stimuli appear with the UCS the same amount of time, all three will be conditioned (uncorrelated condition). • There is no blocking of any stimulus.

34. 3.16 Design and results of the “relative validity” experiment Less learning

35. 3.17 Compounded CSs are probably always present during conditioning