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Chapter 3: Classical Conditioning
PSY 445: Learning & Memory
Pavlovian Conditioning
Pavlov was a research physiologist, not a psychologistAt age 33, earns MDSpends next 20 years
studying the digestive systemRussia’s first Nobel Prize
winner in 1904 Novel work done over the
final 30 years of his life that earns him his place in scientific history Ivan Pavlov
(1849-1936)
Definition of Classical Conditioning
In classical conditioning, the organism learns a connection between two stimuliIn other words, the organism learns that one stimulus
predicts another stimulus A form of associative learning
Learning in which connections are formed between internal representations of events (e.g., stimuli and responses) during learning.
ProcedureClassical conditioning is the presentation of two or
more events in an experimentally determined temporal relationship
Any change in responding to one of the events is seen as evidence of a learned association
Definition of Classical Conditioning
Unconditioned stimulus (US) In classical conditioning, this is the stimulus that
elicits the unconditioned response (UR) without conditioning
Conditioned stimulus (CS) In classical conditioning, this is the stimulus which
comes to elicit a new response by virtue of pairings with the unconditioned stimulus
Unconditioned response (UR) In classical conditioning, the automatic
(involuntary), unlearned reaction to a stimulus Conditioned response (CR)
A learned response elicited as a result of pairings between that NS and an UCS
Pavlov’s Paradigm
Pavlov’s Participants
Methods of Studying Classical Conditioning
Eyeblink Conditioning
Skin Conductance Response
Conditioned Taste Aversion
Evaluative Conditioning
Eyeblink ConditioningThe procedure is relatively simple and usually consists of pairing an auditory or visual stimulus (CS) with an eyeblink-eliciting US For example, light might be paired with a mild puff of air to the cornea or a mild shock
After many CS-US pairings, an association is formed such that a learned blink, CR, occurs and precedes US onsetThe magnitude of learning is generally gauged by the percentage of all paired CS-US trials that result in a CR
In this video clip, experimenter paired puff of air with pencil tap
Skin Conductance Response (SCR) Electrodes put on the arm or palm A loud unexpected noise or mild shock (US)
will usually cause this response (OR) Soft tone or light may be presented before the
US Several pairings Just the tone or light (CS) will produce the SCR
(CR)
Electrodes will be put on participants prior to presentation of CS-US pairings
Conditioned Taste Aversion
Typical ProcedureRats are given novel taste (saccharin-flavored water) is followed by an illness-producing drugGastrointestinal distress Flavored water is again presented
Typical ResultsDecrease or complete avoidance of the flavored water (CS)
Evaluative Conditioning
A change in liking, which occurs due to an association with a positive or negative stimulusNeutral stimulus is paired with something one likes or dislikes Is not reflex-evoking
After these movies came out in 1980s, the hockey mask was never the same
Evaluative Conditioning
Typical ProcedureAn affectively neutral stimulus is presented along with another stimulus that already evokes some type of affective evaluationFor example, a word (NS) is paired with an bad odor (US)Typical ResultsEmotional tone of the neutral stimulus will change to correspond to the USThe word (CS) will come to evoke a negative feeling (CR) from the person who has gone through this type of conditioning
Evaluative Conditioning
Hammerl, Bloch, & Silverthorne (1997)
ProcedureScenic pictures were pre-ratedPictures that were originally rated as neutral (NS) were then paired (five trials) with either pictures that were rated low or rated high (US)ResultsWhen paired with the high-ranked pictures, the neutral pictures received more positive ratings then before; when paired with the low-ranking pictures they received less positive ratings then beforeThus, the originally neutral pictures become the CS and the resultant ratings of these pictures become the CR
Evaluative Conditioning
LimitationsDoesn’t fit classical conditioning pardigm
completelyReliance just on verbal reports is questionableSome believe the changed preferences are based
on conscious knowledge; not automatic responses
What stimuli can serve as CSs?Exteroceptive Stimuli Stimuli involving events outside the body that stimulate the sensory receptorsExamples of exteroceptive stimuli include sounds, sights, smells, touch sensations, tastes, and the likeInteroceptive Stimuli Stimuli inside the body that reflect some change in an internal stateExamples of interoceptive stimuli include body sensations such as a full bladder or empty stomach
What stimuli can serve as CSs? Contextual Stimuli
The place or environment where training occurs are readily conditioned○ Fear of dentist’s office
Temporal StimuliThe passage of time since the last US serves as the
CS for the next US○ Marquis (1941) delayed feeding of infants from
usual 3-hour interval Circadian Stimuli
Conditioning of time of day can lead to different CRs
What stimuli can serve as USs? Stimuli that have either biological significance or
acquired significance work effectively as a US
Basic Phenomena of Conditioning
Acquisition Extinction
Spontaneous Recovery
Generalization Discrimination
Basic Phenomena of Conditioning
AcquisitionWhen the organism first learns the connection between the CS and the US, it is said to be in the stage of acquisition
The initial gain in response strength is large on each trial, and then it levels out at the end of the acquisition period. See graph
Basic Phenomena of Conditioning
AcquisitionControl Procedures – its important to employ these conditions to protect against confounding variables
Unpaired ControlExperimental group gets paired CS-US; control gets CS and US separately
Truly Random ControlCS and US are each separately programmed to occur randomly in time during the experimental sessions along with the usual pairing of CS-US
Basic Phenomena of Conditioning
ExtinctionThe decline or disappearance of the CR in the
absence of the USPresentation of CS alone
Basic Phenomena of Conditioning: Extinction
US ---------------------------------------------- UR NS ----------------------------------------------- NO RESPONSE
NS + US -------------------------------------- UR
* This is repeated several times
CS ------------------------------------------------ CR
Extinction process is initiated:
CS ----------------------------------------------- CRCS ----------------------------------------------- CR (less response than before)CS ----------------------------------------------- CR (less response than before)CS ----------------------------------------------- CR (less response than before)
Eventually we get………..
NS --------------------------------------------- NO RESPONSE (bell) (no salivation)
Basic Phenomena of ConditioningSpontaneous RecoveryAn extinguished CR will temporarily reappear if after a time delay the CS is presented again even without the UCSThis is a reappearance of a CR after extinction despite no further CS-UCS pairingsApparently, extinction does not eliminate the CS-US association; just suppresses it
Trial 11 represents a two-week rest period
Spontaneous Recovery
What happens next?
Extinction continues CS-US pairing
Basic Phenomena of Conditioning Generalization After a CR is acquired, stimuli that are similar but not
identical to the CS also will elicit the response The greater the similarity between a new stimulus
and the CS the stronger the CR will be
Conditioned to tone of F
Basic Phenomena of ConditioningDiscrimination
Organisms can be conditioned to learn to differentiate among similar stimuliEven a similar tone will not produce a response in
certain situations○ For instance, if two tones are continuously
presented but only Tone 1 is paired with the US then CR will only appear when Tone 1 is presented
The Role of Contiguity
This is the belief that the critical factor in determining whether or not classical conditioning would occur was timing The most important thing to control in a classical conditioning experiment was that the CS and the US should be close together in time
Does the sequence matter? Forward Pairing
CS-USStrong conditioning
Simultaneous PairingCS/USNo conditioning
Backward PairingUS-CSWeak conditioning
Other factors effecting conditioning Prior Exposure
Latent inhibition reduces conditioning effect Compound CSs
Usually weaker conditioning to two CSs conditioned together than when done one at a time
SurpriseThe Blocking Effect
See next slide
The Blocking EffectThe Blocking Effect
Experiment 1:
Phase 1 Phase 2 Phase 3
Tone ---- Shock Tone/Light ----Shock AM: Tone---?
* This is repeated several timesPM:
Light---?
Kamin (1969)Kamin (1969)
Rescorla-Wagner Model
This model explains the Blocking Effect
Other factors effecting conditioning
CS-US RelevanceBelongingness – the idea that certain CSs and USs seem to belong together
BelongingnessProcedureRats drink flavored water from tubes that flashed light and made noise when the tubes were licked…
Group 1:○ Rats were given electric shocks to their feet two seconds after
beginning to drink Group 2:
○ Rats were exposed to X rays (which made them sick) while they drank
Later, both groups were tested with: A tube of unflavored water producing lights and noise A tube of flavored water that was not producing lights and noise
○ Rats are basically given a choice between these two tubes to drink from
Garcia & Koelling (1966)
BelongingnessResultsGroup 1 (rats that had been shocked) avoided the tube producing the lights and noise while Group 2 (rats that had been made sick) avoided only the flavored water
InterpretationEvidently, rats (and other species) have a built-in predisposition to associate illness mostly with what they have eaten or drunk (Group 2 rats) and to associate skin pain mostly with what they have seen or heard (Group 1 rats)This is an example of preparedness
Garcia & Koelling (1966)
Conditioned Inhibition
A CS becomes associated with the absence of the USFor example, knowing when food is NOT available
Second-Order ConditioningA new NS can become a new CS
Sensory Preconditioning Two CSs are paired in first phase with no US
For example, tone and light
One of the CSs is paired with food in the second phaseFor example, tone and food
In third phase, the other CS (the one never paired with the US) is testedFor example, light
CR is witnessed
Difference between higher order and sensory preconditioning
The difference is when the two CSs are pairedIn higher-order conditioning, the CS2-CS1 pairing happens AFTER the US has been paired with the CS1In sensory preconditioning, the CS2-CS1pairing happens BEFORE the US has been paired with the CS1
Preparatory Response
A theory of learning that a different form of conditioning, instrumental conditioning, controls the acquisition and performance of conditioned responsesCR are rewarded (a reinforcement theory)
Learning in the Brain
Cerebellum appears to have the key function related to the conditioning processConsidered the final destination for association to take placeLesions in this area of the brain prevent tone-to-eyeblink conditioning
The Role of Awareness in Conditioning Early Pavlovian ideas would say awareness
was not necessary for conditioning Automatic processes
Conflicting studiesSome reports of CS-US contingency suggest that
awareness can be a factorSecondary tasks are often employed
Sometimes participants in these experiments report they are aware of CS-US connections But this does not correlate with the conditioning that is
actually taking place
Extensions of Conditioning
Drug ToleranceDrugs have less of an effect when taken repeatedly (less of a high)Drug users crave more of the drug despite its lessening effectsIt appears that certain drugs trigger our body to call upon its defenses against the effects of the drug
Extensions of Conditioning
Siegel, Hinson, Krank, & McCully (1982)Demonstrated that classical conditioning principles might be in effect during drug-injecting episodesPossible reason for overdoses?
Extensions of Conditioning
US ---------------------------------------------- UR
(drug) (anti-drug defenses)
NS ----------------------------------------------- NO RESPONSE
(injection ritual) (no defenses)
NS + US -------------------------------------- UR
(injection ritual) + (drug) (anti-drug defenses)
* Repeated several times
CS ----------------------------------------------- CR
(injection ritual) (anti-drug defenses)
Siegel’s theory…
Siegel et al. (1982)
Extensions of Conditioning
Familiar setting----------------------- anti-drug defenses (usual time, place, etc) (body reacts)
New setting ---------------------------- no defenses
(place, time are different) (body doesn't react)
The same dosage now becomes an overdose – they get too high as their bodies have been fooled by the new procedure
Siegel et al. (1982)
Extensions of Conditioning
In this experiment laboratory rats were preconditioned to a tolerance of large doses of heroin…Procedure:
○ Lab rats given daily intravenous injections for 30 days○ Placebo or heroin given either in “animal colony” or
alone in “white noise” room on alternate days○ Counterbalance of treatment:
For some rats: heroin in WN; placebo in ACFor others: heroin in AC; placebo in WNControl group received only placebo in different rooms on
alternate days
Siegel et al. (1982)
So this then gives us 3 main Groups:
Group 1: Received heroin in the Colony room (their normal living quarters)
and placebo in the Noisy room the next day Group 2:
Received placebo in the Colony room (their normal living quarters) and heroin in the Noisy room the next day
Group 3: Received placebo in the Colony room (their normal living quarters)
and placebo in the Noisy room the next day
All rats were then injected with a large dose of heroin (15 mg/kg)
Siegel et al. (1982)
But does it depend on the room? But the room in which this potentially lethal dose of heroin was
administered was varied between subgroups of rats… On Day 31:
Group 1A were injected with heroin in the Colony room○ Where they had received all their previous injections of heroin
Group 1B were injected with heroin in the Noisy room○ Where they had never received any previous injections of heroin
Group 2A were injected with heroin in the Noisy room○ Where they had received all their previous injections of heroin
Group 2B were injected with heroin in the Colony room○ Where they had never received any previous injections of heroin
Group 3A were injected with heroin in the Colony room○ Where they had no previous injections of heroin
Group 3B were injected with heroin in the Noisy room○ Where they had no previous injections of heroin
Siegel et al. (1982)
Results: Death Rate
Group 3 showed substantial mortality (96%)
A group with prior exposure in the same cage showed tolerance (only 32% died)
A group with the same history of exposure, but tested in an environment not previously associated with heroin showed higher mortality (64%)
Siegel et al. (1982)
Results: Death Rate
Results50% increase in death rate in new roomRats show "room-specific" tolerance
Siegel (1984)In a follow-up study, overdose victims who had
survived were interviewed and 70% reported they had changed environmental conditions
Siegel et al. (1982)
Conditioning with Drug USs
Siegel (1991)Reviewed studies that tested conditioning after drug exposure by replacing the drug with a placebo injectionMonitoring of body’s conditioned response to the injection procedure (CS) in the absence of the drug (US)Physiological reactions are sometimes opposite of what you would expect from receiving the drugFor example, morphine raises body temperature, placebo lowers it; morphine reduces pain, placebo increases pain sensitivityThis leads to speculation that conditioning can lead to the development of conditioned responses that are the opposite of unconditioned responses
Immune System studies..
Ader & Cohen (1975)Originally intended as a taste aversion experiment they found some incidental results related to our immune system responseRats drank a saccharin solution immediately before the injection of cyclophosphamide, an immunosuppressive drug that also has aversive gastrointestinal side effectsFollowing this pairing, rats avoided drinking the saccharin solution
Immune System studiesAder & Cohen (1975)Results related to immune functioningThe saccharin CS also developed capacity to suppress immune functioning as a CR
Immune System studies
O'Reilly & Exon (1986)These researchers paired a saccharin taste (NS) with the immunosuppressing cyclophosphamide (UCS)
One of cyclophosphamide's natural effects is the reduction of natural killer-cell activity
Natural killer-cells are one of an organism's first defenses against the development of malignant tumors
When they find a cell that has been infected with a virus or one that has become cancerous, they engulf and destroy it
When they presented saccharin to rats, it resulted in a conditioned taste aversion as well as a conditioned reduction in natural killer-cell cytotoxicity
Immune System studiesBovbjerg & Redd (1990)Participants
20 female ovarian cancer patientsProcedure
Chemotherapy given to patients in hospital settingPatients return home within 24-48 hours after
treatmentHypothesis
Classically conditioned anticipatory nausea and vomiting (ANV) and anticipatory immune suppression (AIS)
Immune System studies US ------------------------------------------- UR
(chemo) (nausea/vomiting) NS -------------------------------------------- NO RESPONSE
(hospital) (no reaction) NS + US ----------------------------------- UR
(hospital) (chemo) (nausea/vomiting) * This is repeated several times…
CS --------------------------------------------- CR(hospital) (nausea/vomiting)
Bovbjerg & Redd (1990)
Immune System studies US ------------------------------------------- UR
(chemo) (immunosuppressive)
NS -------------------------------------------- NO RESPONSE
(hospital) (no reaction) NS + US ----------------------------------- UR
(hospital) (chemo) (immunosuppressive)
* This is repeated several times…
CS --------------------------------------------- CR(hospital) (immunosuppressive)
Bovbjerg & Redd (1990)
Immune System studiesResultsParticipants experienced both decreased immune function and increased nausea when they returned to hospital settingImmune suppression occurred after being brought to the hospital but before the next round of chemotherapy actually began
Could the immune suppression be a CR?In certain disorders, an overactive immune system
attacks the body and thus suppression becomes a desirable treatment.○ Therefore, could a placebo in this case have a
practical application?
Bovbjerg & Redd (1990)
Behavioral Medicine
Implantable cardiac defibrillator (ICD) delivers electric shock to its users whenever irregular heart rate occursSome report intense shocks that can cause them to fear places or situationsPairing of shock with a variety of CSs
The conditioning theory of phobias…Watson & Raynor (1920) Behavioral psychologists John Watson and grad assistant Rosalie Raynor taught an 11-month old infant to become afraid of a gentle white laboratory rat
Little Albert reacting to mask worn by John Watson
This illustrates generalization
Preparatory-Response Theory
The purpose of CR is to prepare organism for the UCSThe dog salivates to the tone so as to get ready for
the presentation of the foodThe rat freezes in response to the light so it is ready
for the painful shockTaste-aversion learning
Preparedness leads us to acquire certain fears that have high survival value
Preparatory-Response Theory
LimitationsFears are not limited to preparedness stimuli
Dental anxiety, etc.Fears tend to be age-related
Young children more easily develop animal fears; teenagers more easily develop social fears, etc.
Extinction as a therapy…Exposure treatments can again be utilized to help treat phobiasSystematic desensitizationCounterconditioning occurs as phobia (CS) is paired with US that is incompatible with the phobia
Jones (1924)Removed a fear of rabbits in a young child by pairing ice cream (US) with presentations of the rabbit (CS)
Credits Some slides prepared with the help of the following websites:
http://ibs.derby.ac.uk/~keith/b&b/tolerance.ppt http://salmon.psy.plym.ac.uk/year3/DrugAbuse/drugtolerance.htm http://drmillslmu.wikispaces.com/file/view/
Psych310RomanticRedPresentation.ppt http://gcuonline.georgian.edu/field_ps432_40/Terry03.htm dogsbody.psych.mun.ca/2250/lecture%206.ppt people.uncw.edu/dworkins/psy41703ppt/Chapter11.pptwww.columbia.edu/cu/.../courses/.../powerpoints/lect5_cc2.ppt