facebook group: the group is called: psych281 spring08 available only to university of alberta...
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Facebook Group:The group is called:
Psych281 Spring08Available only to University of Alberta network
Sorry to be rude but…Please don’t add me as a friend (avoiding any
kind of favoritism, etc…)
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?
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)
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)
Intertrial IntervalITITime between each CS-US pairing (i.e.,
between trials)Generally, around 30 seconds effective
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!!
All Together Now!
Trials/Time
Str
en
gth
of
CR
Acquisition ExtinctionSpontaneous Recovery Reacquisition
CS&US CS alone CS alone CS&US
Stimulus Substitution TheoryPavlovCR and UR produced by same neural region
Response centerCS takes on properties of USSubstitution
UScenter
CScenter
Responsecenter
But…CR should be the same as UR
e.g. signtracking, autoshapingBut it’s NOT!!Intensity, magnitudesOmissions & additions
Different CSs elicit different CRsCompensatory responses
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