General Psychology 1

Learning: Classical Conditioning – Module 20

March 17, 2005Class #16

What is Learning?

Learning is a relatively permanent change in behavior due to experience

We learn primarily by identifying relationships between events and noting regularity of patterns in our world

Ivan Pavlov (1849-1936) Was a research physiologist, not a

psychologist At age 33, earns MD degree Spends next 20 years studying

the digestive system Russia’s first Nobel Prize winner

in 1904 Very impressive stuff but not what

he’s remembered for… Rather its his novel work done

over the final 30 years of his life that earns him his place in scientific history

Sometimes its just better to be lucky…

Pavlov serendipitously discovers the conditioning response He’s working on digestive system and is

measuring the amount of saliva his dogs were producing when food was presented to them…

But then “psychic secretions” start messing up his experiments

Ivan Pavlov

First, considered them as an annoyance but then realized he had stumbled onto something of even greater importance… Devotes rest of life until his death at age 86

exclusively to the study of learning

Classical Conditioning

Important Terms Acquisition

Initial learning of the stimulus-response relationship

Neutral stimulus (NS) In classical conditioning, the NS does not initially elicit

the response that is being studied Unconditioned stimulus (UCS)

In classical conditioning, this is the stimulus that elicits the unconditioned response (UR) without conditioning

Classical Conditioning

Important Terms 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 (UCR) 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

Classical Conditioning

Also, keep in mind the influences of such things as timing, predictability (expectancy), signal strength and attention…

Classical Conditioning

A form of learning in which a neutral stimulus (NS), is paired with an unconditioned stimulus (US)… In effect, what has to be learned is the relation between these

two stimuli

Eventually, through this learning process the NS evokes a response which once it did not thus making it a conditioned stimulus (CS)… This is accomplished by repeatedly pairing a neutral stimulus

with a stimulus that already triggered a reflexive response until the NS alone is evoking that same reflexive response

Classical Conditioning

Behaviors that are classically conditioned are those which involve the learning of involuntary (reflexive) responses -- responses over which the learner has no control and to which he or she responds reflexively or "automatically“ Examples include a dog salivating at the sound of the

dinner bell, a horse flinching or shying away at a blowing piece of paper, someone becoming nauseous at sight of "creamy-looking" food when mayonnaise once made them ill, etc.

Pavlov’s Classical Conditioning Experiments

UCS ------------------------------------------- UCR(food) (salivation)

  NS -------------------------------------------- NO RESPONSE

(tone) (no salivation)  NS + UCS ----------------------------------- UCR

(tone) (food) (salivation)* This is repeated several times…

 CS --------------------------------------------- CR(tone) (salivation)

Classical Conditioning:Extinction

The decline or disappearance of the CR in the absence of the UCS

Classical ConditioningExtinction

UCS ---------------------------------------------- UCR  NS ----------------------------------------------- NO RESPONSE

NS + UCS -------------------------------------- UCR*Repeated several timesCS ------------------------------------------------ CR

Extinction process is initiated:

CS ----------------------------------------------- CRCS ----------------------------------------------- CRCS ----------------------------------------------- CRCS ----------------------------------------------- CR

Eventually we get………..

NS --------------------------------------------- NO RESPONSE (tone) (no salivation)

 

Classical Conditioning:Reconditioning

Quick relearning of conditioned response after the extinction trials

Classical ConditioningReconditioning

UCS ----------------------------------------------------- UCRNS ------------------------------------------------------ NO RESPONSE NS + UCS --------------------------------------------- UCR

* Repeated several times

CS ------------------------------------------------------ CRCS ------------------------------------------------------ CRCS ------------------------------------------------------ CRCS ------------------------------------------------------ CR

NS ----------------------------------------------------- NO RESPONSE

Reconditioning process is initiated:

NS + UCS -------------------------------------------- UCRCS ----------------------------------------------------- CR

Classical Conditioning:Spontaneous Recovery

An extinguished CR will temporarily reappear if after a time delay the CS is presented again even without the UCS

This is a reappearance of a CR after extinction despite no further CS-UCS pairings

Classical Conditioning: Stimulus Generalization

After a CR is acquired, stimuli that are similar but not identical to the CS also will elicit the response – but to a lesser degree The greater the similarity between a new

stimulus and the CS the stronger the CR will be

Classical Conditioning Generalization

UCS --------------------------------------------- UCR(food) (salivation)

  NS + UCS ------------------------------------ UCR

(low tone) (food) (salivation)* Repeated several times

NS + UCS ------------------------------------- UCR(medium tone) (food) (salivation)*Repeated several times

NS + UCS ------------------------------------- UCR(high tone) (food) (salivation)* Repeated several times

 

Classical Conditioning Generalization

CS --------------------------------------------- CR

(high tone) (salivation)

CS -------------------------------------------- CR

(low tone) (salivation)

CS -------------------------------------------- CR

(medium tone) (salivation)

Classical Conditioning:Stimulus Discrimination

Organisms learn to differentiate among similar stimuli In Pavlov's early experiments he could get

dogs to discriminate between the pitches of certain tones

Classical Conditioning:Discrimination

UCS ------------------------------------------------------ UCR(food) (salivation)

NS ------------------------------------------------------- NO RESPONSE (low tone) (no salivation)

NS ------------------------------------------------------ NO RESPONSE (medium tone) (no salivation)

NS ----------------------------------------------------- NO RESPONSE (high tone) (no salivation)

NS + UCS -------------------------------------------- UCR(high tone) (food) (salivation) * Repeated several times

Classical ConditioningDiscrimination

CS ------------------------------------------------------ CR(high tone) (salivation)

NS ----------------------------------------------------- NO RESPONSE (low tone) (no salivation)

NS ---------------------------------------------------- NO RESPONSE (medium tone) (no salivation)

CS ----------------------------------------------------- CR(high tone) (salivation)

Kamin (1969) 

Experiment 1:

Phase 1 Phase 2 Phase 3

 

Tone ---- Shock Tone/Light ----Shock Tone---???

Light---???

Kamin (1969)

Experiment 2:

Phase 1 Phase 2 Phase 3 Eliminated Tone/Light ----Shock Tone---???

Light---???

Classical Conditioning: Second-order conditioning

Phase 1:UCS (Food) UCR (salivation)NS1 (Tone) NO RESPONSE NS1+ UCS (Tone/Food) UCR (salivation)

* Repeated several timesCS (Tone) CR (salivation)

Phase 2:NS2/CS (Light/Tone) CR (salivation)

* Repeated several times

Phase 3:NS2 (Light) What do you think

happens?

Second-order conditioning

Here’s a summary of previous slide:

Phase 1 Phase 2 Phase 3

Tone Food Light Tone Light

(salivation) (salivation) (?????)

Here, a CS that has previously been conditioned is now used to condition another NS

Rescorla (1987): Second-order conditioning

Phase 1:UCS (Food) UCR (salivation)NS NO RESPONSE NS + UCS (Tone/Food) UCR (salivation)* Repeated several timesCS (Tone) CR (salivation)

Phase 2:UCS (Food/Poison) CR (salivation)

Phase 3:CS (Tone) What do you think

happens?

Rescorla (1987)

Here’s a summary of previous slide:

Phase 1 Phase 2 Phase 3

Tone Food Food (Poison) Tone

(salivation) (salivation) (?????)

 

What do you think happened???

Classical Conditioning:Drug Tolerance Example

Drug Tolerance Drugs have less of an effect when taken repeatedly

(less of a high) Drug users crave more of the drug despite its

lessening effects It appears that certain drugs trigger our body to call

upon its defenses against the effects of the drug

Drug Tolerance

Siegel et al. (1982) Demonstrated that classical conditioning principles

might be in effect during drug-injecting episodes… Possible reason for overdoses???

Siegel’s theory…

UCS ---------------------------------------------- UCR

(drug) (anti-drug defenses)

  NS ----------------------------------------------- NO RESPONSE

(injection ritual) (no defenses)

NS + UCS -------------------------------------- UCR

(injection ritual) + (drug) (anti-drug defenses)

* Repeated several times

CS ----------------------------------------------- CR

(injection ritual) (anti-drug defenses)

 

Siegel’s theory…

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’s Model

Initial Exposure

Sight of needle, taste of beer, etc.

Neutral Stimuli

Effects of drug on neurons

UCS

Compensatory reaction opposing drug effects

UCR

Later Effects

Sight of drug-associated stimuli

CS

Compensatory reactions. Resemble withdrawal effects in the absence of the drug.

CR

Siegel, Hinson, Krank, & McCully (1982)

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 AC For others: heroin in AC; placebo in WN Control group received only placebo in different rooms on

alternate days

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)

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… 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 - they had

no previous injections of heroin Group 3B were injected with heroin in the Noisy room - they had no

previous injections of heroin

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%)

Results: Death Rate

Results: 50% increase in death rate in new room Rats show "room-specific" tolerance

Information contained on slides #36-39 taken from following website: http://salmon.psy.plym.ac.uk/year3/DrugAbuse/drugtolerance.htm

Slide # 35 prepared by Keith Clements and taken from his website: http://ibs.derby.ac.uk/~keith/b&b/tolerance.ppt