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Ivan Petrovich Pavlov (1849-1936)Pavlovian (Classical) conditioningPhysiologistDigestion

DogsConditional redirection of reflexes

Conditional reflexes

Conditional??Yes, conditional

Mistranslated to conditioned

For learning at least, this is where the term “conditioning” came from

TerminologyUnconditional stimulus (US)

Stimulus that elicits the innate reflex (e.g., food)Unconditional response (UR)

Reflex action that occurs in response to US (e.g., salivation)

Conditional stimulus (CS)Any stimulus that doesn’t originally elicit the UR

(e.g., buzzer)Conditional response (CR)

The action elicited by the CS (e.g., salivation)THIS IS LEARNED

The BasicsUse behaviours that are already in place –

ReflexesAssociate some new (neutral) stimulus with

the stimulus that evokes the reflexHow? Present them together!

Buzzer-food (salivate)Buzzer-food (salivate)Buzzer-food (salivate)Buzzer-?

- CS-US UR- CS-US (CR) UR- CS-US (CR) UR- CS CR

The BasicsTIME

Conditional Stimulus

on

off

Unconditional Stimulus

on

off

Unconditional Response

(after enough pairings)Conditional Response

Measuring ConditioningSometimes difficult to measure CR

e.g., if CS & US close together, CR & UR can overlap

Buzzer-food-saliva, buzzer-saliva-food? How long is the separation between the buzzer and

the food?

IntensityDoes CR intensity increase with experience?

Test trial (probe trial)Give CS alone

Probe (Test) TrialsTIME

Conditional Stimulus

on

off

Unconditional Stimulus

on

off

No Unconditional Response without the US!

Conditional Response?

Some notes & examples…Awareness is NOT necessaryEyeblinkConditioned Suppression (Conditioned

Emotional Response)Suppression ratiosAnother way of MEASURING conditioning

Taste AversionTequila?

S-S or S-R?

US

CS

Response

What kind of connection is being made?

Rescorla (1973)So, how do you get rid of a response that is

hard wired to a stimulus?How can you get rid of a reflex?Habituation

Results

Less suppression in Habituation group(In other words, more responding)

Therefore, the connection MUST be S – S

GroupGroup Phase 1Phase 1 Phase 2Phase 2 TestTest

HabituationHabituation L L N N (startle)(startle)

Noise Noise (habituate)(habituate)

LightLight

ControlControl L L N N (startle)(startle)

NothingNothing LightLight

Higher Order ConditioningS-S-S?CSs and USs can be associated (First-order)CSs can be associated with other CSsSecond-order conditioning

salivation (CR)

first-order CS

tone (CS1) food (US)

second-order CS

Light (CS2)

Types of ConditioningDelay

ShortLong

TraceSimultaneousBackwardsInhibitory

Delay ConditioningCS and US overlapShort

Usually the most effective

Longtiming

Trace ConditionFrom “memory trace”Must remember CSOther stimuli interfere

CS

US

GAP

Simultaneous conditioningWeaker than short delayCS can’t signal onset of US

Not predictive

CS

US

Backwards conditioningMuch more difficultIgnores order

CS

US

Conditioned InhibitionCS-

Up until now, we’ve been talking about CS+CS signals the ABSENSE or NON-

OCCURRENCE of USNeeds to be some expectation of the US for

this to work

CS+

US

CS-

Factors that affect conditioningContiguityContingencyStimulus FeaturesPrior ExperienceNumber of PairingsIntertrial Interval

ContiguityCloseness together in time and/or spaceUsually, more learning if greater contiguity

between CS & USType of conditioning may influence thise.g., eyeblink vs. taste aversion

BUT, contiguity is not sufficient!

Group CS-US pairings

US alone CR strength

A .40 0 Very strong

B .40 .10 strong

C .40 .20 Medium

D .40 .40 weak

ContingencyIf-then situationConsistency of pairing CS and USGreater contingency, greater learninginformative

Stimulus FeaturesIntensity of stimuli (CS & US)Compound Stimuli

Two+ simple CSs presented at the same timePaired with USOvershadowing – if one CS is more salient, the

other CS may be ignoredNature of Stimuli (relevance or

belongingness)Loud & noisy water?

Prior experiencePrior experience with CS and/or US affects

conditioningcontingency

Latent inhibitionPrior experience with an neutral stimulus

makes it harder for it to become a CS laterNovelty

BlockingIntroducing a new CS (CS2) in compound with

an already trained CS (CS1)CS2 won’t be learned about

Sensory preconditioningPair two CSsPair one with a USUnpaired CS still elicits CR

Phase 1 (CS1+CS2):-Light + Tone-Light + Tone-Light + Tone

Phase 2 (CS1+US):-Light + Food-Light + Food-Light + Food

Test (CS2?)-Tone?(measure response)

Number of PairingsAcquisition curveNon-linearAsymptote

Conditioning Trials

CR

Str

en

gth

asymptote

Intertrial IntervalITITime between each CS-US pairing (i.e.,

between trials)Generally, around 30 seconds effective

Extinction, Spontaneous Recovery and Reacquisition

ExtinctionContinued pairing of CS with US maintains

CRCS without US --> ExtinctionWeakening and stopping of CR

Not forgettingA type of conditioning

Withhold respondingCS paired with absence of US

Spontaneous RecoveryAfter extinction, let time passPresent CS again (no US)Temporary, small return of CRShows extinction is not forgetting!!

ReacquisitionExtinguish CRRecondition with CS-US pairingFewer trials required

All Together Now!

Trials/Time

Str

en

gth

of

CR

Acquisition ExtinctionSpontaneous Recovery Reacquisition

CS&US CS alone CS alone CS&US

How does this all work?

Stimulus Substitution TheoryPavlovCR and UR produced by same neural region

Response centerCS takes on properties of USSubstitution

UScenter

CScenter

Responsecenter

Sign Tracking

Food

Sign Tracking

But…CR should be the same as UR

e.g. signtracking, autoshapingBut it’s NOT!!Intensity, magnitudesOmissions & additions

Different CSs elicit different CRsCompensatory responses

Preparatory Response TheoryLearn responses that prepare organism for

US occurrenceSometimes CR same as UR, sometimes

differentDrug Tolerance