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 requiredBelongingnessKamin: Surprise
10 Leon Kamin: BlockingUS has to be “surprising” to the animal for learning of the CS-US association to occur.Group Phase 1 Phase 2 TestBlock AUS AXUS X?Control BUS AXUS 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 requiredBelongingnessKamin: SurpriseRelative salience
12 Salience effectsOvershadowing – in compound conditioning, the more salient CS winsGroup Treatment Test xOvershadow Ax crControl x+ CROvershadowing is a cue-competition effect, like blocking.
13 Overshadowing (Blaisdell et al., 1998) GroupTrainingTestCRControlOvershadow+cr
14 Conclusion thus far:Forward pairings (contiguity) neither necessary nor sufficient.Something more is requiredBelongingnessKamin: SurpriseContingencyRelative salienceBlocking is itself a contingency effect
15 Rescorla’s contingency experiment CSUSCorrelatedGroupRate of US Occurrence: 0.1US/sec during CS; 0US/sec outside of CSCSUSUncorrelatedGroupRate of US Occurrence: 0.1US/sec during CS; 0.1US/sec outside of CS
16 Rescorla’s contingency experiment CSCorrelatedGroupUSRate of US Occurrence: 0.1US/sec during CS; 0US/sec outside of CSCSUncorrelatedGroupUSRate of US Occurrence: 0.1US/sec during CS; 0.1US/sec outside of CS
19 CR Results of Rescorla’s (1968) Contingency Experiment .4 .1 .2 P(US | CS) = .4 for all groupsP(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 preexposureGroup Phase 1 Phase 2 Test CSExperimental US CSUS crControl CSUS CRCS preexposureExperimental CS- CSUS 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 USContingency: “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 stimulusSo 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 US2. 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…AUS / AX
29 Second-Order Conditioning A+/AX- training. Look familiar?However, number of AX- trials is criticalFew AX- trials leads to SOCMany AX- trials leads to conditioned inhibitionalso, 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 ConditioningPhase 1 Phase Test XA+ AX CR(Few AX- trials -- typically not more than 8-10)
32 The Rescorla-Wagner Model (1972) ∆VCS = αβ(λ-VSUM)∆VCS = change in associative strength of CSVCS = associative strength of CSλ = Asymptote of learningLearning rate parametersα = CS salience (0-1; 0 = no CS)β = US salience (0-1; 0 = no US)
35 R-W model accounts for: Blocking (Kamin)Overshadowing (Pavlov)Ax+, A-US association develops faster than X-USCSs have unequal learning rate parameters.Conditioned inhibition (Pavlov)A+/AX-, (λ-VA+X) = (0-[1+0]) = -1X develops negative associative strength!
36 Overexpectation Effect Group Ph. 1 Ph Test XExperimental A+/X+ AX+ crControl A+/X CR
37 What is learned in CC? UR UR CS CS US US Clark Hull (S-R theory) Pavlov (S-S theory)URURCSCSUSUSS-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 TestTonePellet PelletRotation ToneCRPellet | Rotation Tone CRWhat 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.