PSY402 Theories of Learning

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Nov 14, 2013 (3 years and 7 months ago)

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PSY402

Theories of Learning

Chapter 3 (Cont.)

Indirect Conditioning

Applications 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.