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Classical Conditioning II. What are the necessary conditions for classical conditioning?

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Presentation on theme: "Classical Conditioning II. What are the necessary conditions for classical conditioning?"— Presentation transcript:

1 Classical Conditioning II

2 What are the necessary conditions for classical conditioning?

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

4 Is contiguity necessary?

5 Conditioned taste aversion methodology Distinctive flavor LiCl injection

6 Choice Test vs ?

7 Is contiguity sufficient?

8 CS-US belongingness 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 GroupPhase 1Phase 2Test Block A  USAX  USX? Control B  USAX  USX? US has to be “surprising” to the animal for learning of the CS-US association to occur. 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 GroupTreatmentTest x OvershadowAx+ cr Control x+ CR

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

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

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

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

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

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

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

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 GroupPhase 1Phase 2Test CS Experimental USCS  US cr Control ----CS  US CR CS preexposure GroupPhase 1Phase 2Test CS Experimental CS-CS  US cr Control ----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

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 Inhibition A US A A A A A A A X A X X

27

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 1Test X A+/AX- CI (Many AX- trials -- tens to hundreds) Design of Second-Order Conditioning Phase 1Phase 2 Test X A+AX- CR (Few AX- trials -- typically not more than 8-10)

31 Classical Conditioning Simulator

32 ∆V CS = change in associative strength of CS V CS = 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) ∆V CS = αβ(λ-V SUM ) The Rescorla-Wagner Model (1972)

33 R-W and Blocking ∆V CS = αβ(λ-V SUM ) Blocking group ∆V X = αβ(λ -V A+X ) ∆V X = 1(1 –[1+0]) = 0 Acq group ∆V X = αβ(λ -V A+X ) ∆V X = 1(1 – [0+0]) = 0 GroupPh. 1 Ph. 2 λ V A Block A+ AX+ 1 1 Acq B+ AX+ 1 0 Phase 2

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-V A+X ) = (0-[1+0]) = -1 X develops negative associative strength!

36 Overexpectation Effect GroupPh. 1 Ph. 2 Test X ExperimentalA+/X+AX+ cr ControlA+/X+ --- CR

37 What is learned in CC? CSUSUR Clark Hull (S-R theory)Pavlov (S-S theory) CSUSUR

38 Test – Devaluation Experiment Holland & Straub (1979) TrainDevaluationTest Tone  PelletPellet  RotationTone  CR Pellet | RotationTone  CR


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