PSY402Theories of Learning

Chapter 3 (Cont.)Indirect ConditioningApplications of Conditioning

Midterm Results

Contemporary Theories

Classical Conditioning: Nature of the CR – stimulus substitution

theory, SOP and AESOP theory Predictiveness of the CS – Rescorla-

Wagner associative model, comparator theory, attentional theory, retrospective processing approach.

Stimulus-Substitution Theory

What is the nature of the CR – is it just the UCR or is it different?

Pavlov – stimulus-substitution theory: The CS stimulates the same areas of

the brain as the UCS, producing the same response.

Activation of CS with UCS establishes neural connection between brain areas.

Conditioned Opponent Response

The CR and UCR are often different: CR of fear is different than UCR of pain.

Siegel – best evidence of difference: Morphine (UCS) produced analgesia,

reduced pain (UCR) Light or tone (CS) produced

hyperalgesia, increased pain (CR). Rats remove paws from heat quickly

with CS, slowly with UCS. Insulin (glycemia) works the same way

Drug Tolerance Overdoses

Elimination of a CS results in a stronger response to the UCS, drug. Extinction of responding to environ-

mental cues strengthens drug response Changing the context in which a

drug is administered increases response to the drug. Novel environment does not elicit an

opponent CR.

SOP Theory

Sometimes Opponent-Process theory (SOP) – explains why CR varies.

UCS elicits primary A1 (fast) and secondary A2 (longer) responses. A1 & A2 can be same or different.

Conditioning only occurs to A2 – the CR is always an A2 response. When A1 & A2 differ, UCR & CR differ.

SOP Explains Timing Effects

None of the previous models explain why the timing of CS-US matters.

SOP model requires that both CS and UCS be in the A1 stage for learning to occur. With delay more elements of CS decay

from A1, becoming A2.

Activation of a memory node in SOP theory

Conditions during delay conditioning

Learning occurs only for the elements whose A1 stages overlap

Conditions during trace conditioning

Without overlap, no conditioning occurs

Conditions during backward conditioning

CS comes after the US

Inhibition is conditioned because the CS A1 overlaps US A2 stage

Two-Phase Reactions

Shock – results in: A1 -- Initial agitated hyperactivity A2 -- Long-lasting hypoactivity

(freezing) CER (fear) elicited by CS is A2

Morphine – results in: A1 – sedation, analgesia & hypoactivity A2 – hyperactivity two hours later &

hyperalgesia (greater pain sensitivity) CR elicited by CS is A2 (hyper)

Affective Extension of SOP Theory

Why do different A2 responses have different optimal CS-UCS intervals?

Two distinct UCR sequences activate distinct A1 & A2 sequences: Sensory Emotive

These distinct sequences can have different strengths, time scales (latencies), or eliciting CS’s.

Faster

Slower

Rescorla-Wagner Theory

There is a maximum associative strength between CS and UCS. UCS determines the limit

Strength gained on each training trial depends on prior training. More learning early, less later on

Rate of conditioning varies. Conditioning of a CS depends on

prior conditioning to other stimuli.

UCS Preexposure Effect

If the UCS is encountered without the CS prior to pairing of the two, less learning occurs.

UCS becomes associated with other environmental stimuli (without CS).

Since there is a limit to association strength, some is drained off by such prior associations. CS-UCS association is weakened.

Problems with Rescorla-Wagner

Overshadowing – salient cues have more associative strength. Sometimes a salient cue potentiates

another cue instead of overshadowing. Garcia says cues are indexed. R-W says cues are seen as unitary

stimulus. Unclear which explanation is

correct.

More Problems

CS preexposure effect – appearance of CS without UCS prior to learning weakens learning. Shouldn’t have any effect according to

Rescorla-Wagner theory, but it does. Cue-deflation effect – extinction of a

more salient cue enhances learning for the less salient cue. Should be no change according to R-W.

Comparator Theory

If two CS’s are associated, extinction of one should reduce responding to the other. Sometimes true, other times not.

CS-UCS associations exist for many stimuli but are exhibited only for the strongest. Comparator theory says the CS’s are

judged in relation to each other.

Organisms might learn about elemental or configural CS nodes

Pearce

Wagner & Brandon

Attentional View

Mackintosh – learned irrelevance occurs during preexposure of CS.

Animals exposed to a novel stimulus exhibit an orienting response. No orienting with preexposure. Habituation results in failure of

conditioning – no attention is paid to a habituated stimulus.

Pairing of CS/UCS in novel context results in learning.

Retrospective Processing

Most theories assume the level of responding will be constant after learning.

Baker & Mercier suggest association can change after learning. Retrospective processing – CS-UCS

contingency reevaluated after learning. Backward blocking – support for theory Suggests animals have mental

representations, memory for events.

Applications of Conditioning

Treatment of phobias Systematic desensitization

Treatment of addictions Elimination of conditioned withdrawal

reactions Enhancement of drugs used to treat

immune system disorders Lupus, AIDS

How a Phobia Works

A phobia is an unrealistic fear. A learning experience causes fear to

become associated with a neutral stimulus.

Avoidance prevents extinction. The stimulus is generalized. Eventually, too many experiences

must be avoided and a person’s functioning is impaired.

Systematic Desensitization

Wolpe applied ideas from classical conditioning to treatment of phobia. Reciprocal inhibition – an organism can

only feel one emotion at a time. Mary Cover Jones – used

counterconditioning to extinguish fear. Cats could be counterconditioned using

food.

Clinical Procedure

Construct an anxiety hierarchy. Teach a relaxation response.

Cue-controlled relaxation. Counterconditioning – pairing of

relaxation with imagined feared stimuli, starting with least scary.

Assessment of whether the treatment worked – interacting with the feared stimulus.

Effectiveness of Desensitization

Wolpe reported 90% success rate, compared to 60% for psychoanalysis. 12-29 sessions Relapse after 1-3 yrs easily treated.

Works with a wide range of fears. Can also be used with anxiety

disorders.

Limitations on Desensitization

The client must be able to vividly imagine the feared stimulus. 10% cannot do this.

Confrontation of a real rather than an imagined object is more effective. Difficult for the client to endure the

anxiety associated with this.

Virtual Reality Desensitization

Graded height-related stimuli presented via virtual reality were effective in treating acrophobia. Subjects were able to endure real

stimuli after virtual treatment. Successful in treating spider phobia.

Treatment of Withdrawal

Conditioned withdrawal reaction – environmental cues become associated with withdrawal stage. Exposure to cues triggers symptoms. Withdrawal motivates substance use.

Extinction by exposure to environmental cues is needed.

Virtual reality also used to treat addictions.

Treatment of Immune Disorders

Lupus, AIDS are immune system disorders. Treated using drugs that either boost or

suppress immune system response. Classical conditioning can be used

to produce the results of such drugs without the side effects or cost.

Immune System Conditioning

Cyclophosphamide used to induce nausea during flavor-aversion learning also immunosuppressant. The saccharin-flavored water used as a

CS caused several rats to die. The drug reaction occurred without

the drug – the CS evoked immune system suppression.

Also works with other drugs.

Treatment of Lupus & AIDS

Rats given saccharin paired with cyclophosphamide had slower lupus progression and lower mortality.

A girl treated for lupus was able to use half as much drug when paired with a distinctive taste and smell.

Sherbet paired with adrenaline enhances immune functioning for AIDS treatment.