Current Theoretical Current Theoretical Approaches and Issues in Approaches and Issues in

Classical ConditioningClassical Conditioning

Psychology 3306Psychology 3306

Everything you know is wrongEverything you know is wrong

So, the number of pairings is an important, So, the number of pairings is an important, maybe all important, variable in maybe all important, variable in determining the amount of conditioning, determining the amount of conditioning, right?right?

Fine, then explain Kamin Blocking to me…Fine, then explain Kamin Blocking to me…

Kamin (1968)Kamin (1968)

GroupGroup Phase 1Phase 1 Phase 2Phase 2 TestTest ResultResult

ControlControl NothingNothing LT+LT+ TT CRCR

BlockingBlocking L+L+ LT+LT+ TT No CRNo CR

L = Light T = Tone + = CS (shock)

Blocking is rockingBlocking is rocking Same number of tone Same number of tone

shock pairings in both shock pairings in both groupsgroups

It is NOT just number of It is NOT just number of pairingspairings

The tone predicts nothing The tone predicts nothing in the blocking group in the blocking group (nothing extra anyway)(nothing extra anyway)

These results, and some These results, and some others, lead to the others, lead to the Rescorla Wagner ModelRescorla Wagner Model

You said there’d be no math!You said there’d be no math!

Yes, it is a math modelYes, it is a math modelTrial by trialTrial by trialAssumes you can get excitatory Assumes you can get excitatory

conditioning, inhibitory conditioning or conditioning, inhibitory conditioning or nothingnothing

All based on what the CS predictsAll based on what the CS predictsLet’s look at the rulesLet’s look at the rules

The RulesThe Rules

If the strength of the US is greater than If the strength of the US is greater than expected then excitatory conditioning to expected then excitatory conditioning to the CS is the resultthe CS is the result

If the strength of the US is LESS than If the strength of the US is LESS than expected, then you will get inhibitory expected, then you will get inhibitory conditioningconditioning

The larger the discrepancy between what The larger the discrepancy between what is observed and what is expected, the is observed and what is expected, the greater the conditioninggreater the conditioning

More rulesMore rules

The more salient the CS, the more The more salient the CS, the more conditioning you will getconditioning you will get

Two or more CSs together, their strength Two or more CSs together, their strength is additiveis additive

This is, in essence, a model of surprise! This is, in essence, a model of surprise! The more surprised the animal, the more it The more surprised the animal, the more it learnslearns

The model makes some groovy The model makes some groovy predictionspredictions

Slope of the acquisition curveSlope of the acquisition curveBlockingBlockingConditioned inhibitionConditioned inhibitionOvershadowingOvershadowingOverexpectationOverexpectation

OverexpectationOverexpectation

GroupGroup Phase IPhase I Phase IIPhase II TestTest ResultResult

ExpExp L+ T+L+ T+ LT+LT+ L, TL, T Weak Weak CRCR

ControlControl L+ T+L+ T+ nothingnothing L, TL, T Strong Strong CRCR

The Model:The Model:

ΔΔVVii – S – Sii(A(Ajj-V-Vsumsum)) i = CSi = CS j = USj = USS = SalienceS = SalienceA = Value of the USA = Value of the USV = amount of conditioningV = amount of conditioningThese quantities are, of course, These quantities are, of course,

hypotheticalhypothetical

An exampleAn example

OK, say a food pellet = 100OK, say a food pellet = 100Say salience of a light CS = .2Say salience of a light CS = .2VVsumsum = 0 (at the start of the experiment, = 0 (at the start of the experiment,

there is no conditioning yetthere is no conditioning yet

OK, now for the numbersOK, now for the numbers

Trial 1Trial 1ΔΔVVii – S – Sii(A(Ajj-V-Vsumsum))

=.2(100 – 0)=.2(100 – 0)=20=20

Trial 2Trial 2ΔΔVVi i = .2(100-20)= .2(100-20)=16=16

Continued….Continued….

Trial 3Trial 3ΔΔVVii – S – Sii(A(Ajj-V-Vsumsum))

ΔΔVVi i = .2(100-36)= .2(100-36) -12.8-12.8

And so on….And so on….Less and less conditioning as time goes Less and less conditioning as time goes

bybyCoo ehCoo eh

OvershadowingOvershadowing

CS1 -> Light, S = .2CS1 -> Light, S = .2CS2 -> Noise, S= .5CS2 -> Noise, S= .52 CSs, so two calculations per trial2 CSs, so two calculations per trialTrial 1Trial 1

ΔΔVVLightLight = .2(100-0) = 20 = .2(100-0) = 20

ΔΔVVNoise Noise = .5(100-0) = 50= .5(100-0) = 50

OvershadowingOvershadowing

Trial Trial ΔΔVVLightLight = .2(100-70) = 6 = .2(100-70) = 6

ΔΔVVNoise Noise = .5(100-70) = 15= .5(100-70) = 15

OK, how does blocking work?OK, how does blocking work? Well there is no strength leftWell there is no strength left Conditioned inhibition?Conditioned inhibition? Negative for old CSNegative for old CS Additive modelAdditive model

Stuff it cannot deal withStuff it cannot deal with

CS preexposureCS preexposureChange S?Change S?Mackintosh’s attentional theory does this, Mackintosh’s attentional theory does this,

S becomes an attention parameterS becomes an attention parameterPearce Hall modelPearce Hall modelGallistel’s modelGallistel’s model

Types of associationsTypes of associations

First order conditioning is S-SFirst order conditioning is S-SSecond order is S-S and S-RSecond order is S-S and S-RCS - context associations tooCS - context associations tooUS context associationsUS context associationsContext BlockingContext BlockingCS CS associations in compound stimulus CS CS associations in compound stimulus

experimentsexperimentsOccasion setting (Holland)Occasion setting (Holland)

Constraints on Pavlovian Constraints on Pavlovian ConditioningConditioning

Taste aversionsTaste aversionsNot just sicknessNot just sicknessNot the aftertasteNot the aftertasteOnly to certain elements of the food, which Only to certain elements of the food, which

depends on the speciesdepends on the speciesSpecial?Special?Could just be a quantitative difference Could just be a quantitative difference

(Andrews and Braverman, 1975)(Andrews and Braverman, 1975)

Form of the CRForm of the CR

CR is often like the UR but not alwaysCR is often like the UR but not alwaysWeakerWeakerOpposite directionOpposite direction

Drug toleranceDrug toleranceCompensatory CRs with opiatesCompensatory CRs with opiatesContext as CSContext as CS

Shooting gallery effectShooting gallery effectCould depend on drug action being in PNS Could depend on drug action being in PNS

or CNS (Stewart et al)or CNS (Stewart et al)

Physiological BasisPhysiological Basis

New synapses formed in AplysiaNew synapses formed in Aplysia Increase in transmitter release in neurons Increase in transmitter release in neurons

sensitive to CS (very cool)sensitive to CS (very cool)Just like habituation!Just like habituation!

What about more complex creaturesWhat about more complex creatures

Five points about Physiology Five points about Physiology and conditioningand conditioning

1)1) CR and UR pathways are often CR and UR pathways are often differentdifferent

2)2) CR production is distributedCR production is distributed3)3) Conditioning is distributedConditioning is distributed4)4) Different CRs, different brain regionsDifferent CRs, different brain regions5)5) Sometimes it is individual neuronsSometimes it is individual neuronsMy conclusion then is that we have a very My conclusion then is that we have a very

basic mechanism at work herebasic mechanism at work here