1. Classical Conditioning II

2. What are the necessary conditions for classical conditioning?

3. CS US Delay CS US Trace Explicitly Unpaired minutes CS US CS
Weaker conditioned responding CS US
Delay CS US
Trace
Explicitly Unpaired
minutes CS US CS

4. Is contiguity necessary?

5. Conditioned taste aversion methodology
Distinctive flavor
LiCl injection

6. Choice Test ? vs
CTA in chemotherapy.

7. Is contiguity sufficient?

8. CS-US belongingness From Garcia & Koelling, 1966
Another remarkable finding by Garcia and Koelling was that not all CS’s and US’s are associable.
From Garcia & Koelling, 1966

9. Conclusion thus far:
Forward pairings (contiguity) neither necessary nor sufficient.
Something more is required
Belongingness
Kamin: Surprise

10. Leon Kamin: Blocking
US has to be “surprising” to the animal for learning of the CS-US association to occur.
Group Phase 1 Phase 2 Test
Block AUS AXUS X?
Control BUS AXUS X?
Because A already predicts the US in the Blocking group, the US is not surprising during Phase 2 trials.

11. Conclusion thus far:
Forward pairings (contiguity) neither necessary nor sufficient.
Something more is required
Belongingness
Kamin: Surprise
Relative salience

12. Salience effects
Overshadowing – in compound conditioning, the more salient CS wins
Group Treatment Test x
Overshadow Ax cr
Control x+ CR
Overshadowing is a cue-competition effect, like blocking.

13. Overshadowing (Blaisdell et al., 1998)
Group
Training
Test  CR
Control
Overshadow +  cr

14. Conclusion thus far:
Forward pairings (contiguity) neither necessary nor sufficient.
Something more is required
Belongingness
Kamin: Surprise
Contingency
Relative salience
Blocking is itself a contingency effect

15. Rescorla’s contingency experimentCS US
Correlated
Group
Rate of US Occurrence: 0.1US/sec during CS; 0US/sec outside of CS CS US
Uncorrelated
Group
Rate of US Occurrence: 0.1US/sec during CS; 0.1US/sec outside of CS

16. Rescorla’s contingency experimentCS
Correlated
Group US
Rate of US Occurrence: 0.1US/sec during CS; 0US/sec outside of CS CS
Uncorrelated
Group US
Rate of US Occurrence: 0.1US/sec during CS; 0.1US/sec outside of CS

17. Rescorla’s contingency experimentCS US
Correlated
Group CS US
Uncorrelated
Group
P (US|CS) = 0.5 P(US|noCS) = 0.5

18. P(US | CS)
P(US | ~CS))

19. CR Results of Rescorla’s (1968) Contingency Experiment .4 .1 .2
P(US | CS) = .4 for all groups
P(US | noCS) .4 .1 .2

20. It’s a little like…
Animals are scientists, trying to make causal predictions.
…trying to determine whether the US is contingent on the CS

21. Other Contingency Phenomena
US preexposure effect: Presenting the US repeatedly prior to CS-US trials retards acquisition.
CS preexposure effect: Presenting the CS repeatedly prior to CS-US trials retards acquisition. (a.k.a. Latent Inhibition)

22. US and CS preexposure designs
US preexposure
Group Phase 1 Phase 2 Test CS
Experimental US CSUS cr
Control CSUS CR
CS preexposure
Experimental CS- CSUS cr

23. Factors That Affect Conditioning
Contiguity: The closer two stimuli are in space and time, the stronger can be the association between them.
“Belongingness”: The “fit” between CS and US
Contingency: “Information value.” The higher the correlation between two stimuli, the stronger the conditioned response.
Salience: More intense or noticeable stimuli condition more rapidly.

24. Other conditioning phenomena discovered by Pavlov
Conditioned inhibition: A stimulus predicts the absence of the US.
Second-order conditioning: Pairing a neutral stimulus with a CS confers associative strength upon the neutral stimulus
So far we have seen how classical conditioning involves linking up a neutral stimulus with some sort of response.
Now we’ll see some evidence that conditioning need not involve an overt response.

25. Conditioned Inhibition
Pavlov discovered conditioned inhibition.
A conditioned inhibitor is a stimulus that inhibits the conditioned response.
Two cues used:
1. An “exciter”, which is paired with US
2. The inhibitor, which is presented in compound with the exciter. On those trials the US is not presented. Using the standard notation…
A+/AX- or…
AUS / AX

26. Conditioned InhibitionA X A US

28. Tests for conditioned inhibition

29. Second-Order Conditioning
A+/AX- training. Look familiar?
However, number of AX- trials is critical
Few AX- trials leads to SOC
Many AX- trials leads to conditioned inhibition
also, SOC typically produced in two phases.
- A+ training followed by AX+ training.

30. Design of Conditioned Inhibition Phase 1 Test X A+/AX- CI
(Many AX- trials -- tens to hundreds)
Design of Second-Order Conditioning
Phase 1 Phase Test X
A+ AX CR
(Few AX- trials -- typically not more than 8-10)

31. Classical Conditioning Simulator

32. The Rescorla-Wagner Model (1972)
∆VCS = αβ(λ-VSUM)
∆VCS = change in associative strength of CS
VCS = associative strength of CS
λ = Asymptote of learning
Learning rate parameters
α = CS salience (0-1; 0 = no CS)
β = US salience (0-1; 0 = no US)

33. R-W and Blocking ∆VCS = αβ(λ-VSUM) Group Ph. 1 Ph. 2 λ VA
Block A+ AX
Acq B+ AX
Phase 2
Blocking group
∆VX = αβ(λ -VA+X)
∆VX = 1(1 –[1+0]) = 0
Acq group
∆VX = αβ(λ -VA+X)
∆VX = 1(1 – [0+0]) = 0

34. Rescorla-Wagner Spreadsheet

35. R-W model accounts for:
Blocking (Kamin)
Overshadowing (Pavlov)
Ax+, A-US association develops faster than X-US
CSs have unequal learning rate parameters.
Conditioned inhibition (Pavlov)
A+/AX-, (λ-VA+X) = (0-[1+0]) = -1
X develops negative associative strength!

36. Overexpectation Effect
Group Ph. 1 Ph Test X
Experimental A+/X+ AX+ cr
Control A+/X CR

37. What is learned in CC? UR UR CS CS US US Clark Hull (S-R theory)
Pavlov (S-S theory) UR UR CS CS US US
S-R theory means that the organism knows nothing about the US. It’s just stimulus-responses, and it’s not modulated by information about the CS. So for instance,

38. Test – Devaluation Experiment
Holland & Straub (1979)
Train Devaluation Test
TonePellet PelletRotation ToneCR
Pellet | Rotation Tone CR
What happens after a long night of drinking. At the beginning of the night, that beer looks really good. You see the beer can, you salivate. But the next morning, you take a look at the beer can and you get a little nauseous.