Download Extinction

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Systematic desensitization
◦ Technique developed by Joseph Wolpe
 Teach relaxation skills
 Create fear hierarchy
 Sufferers learn to relax while facing feared objects
 Since relaxation is incompatible with fear, the relaxation
response is thought to substitute for the fear response
◦ Several types:
 In vivo desensitization (live)
 Covert desensitization (imagined)
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Guided Reduction in fear, anxiety or aversion
 Attained by gradually increasing anxietytriggering stimuli while maintaining relaxation
 Very effectively used for phobias, intense, unrealistic
fears
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Hierarchy
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Reciprocal Inhibition
 Rank-ordered series of steps, amounts, or
degrees
 One emotional state is used to block another;
impossible to be anxious and relaxed at the same
time
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Model: Live or filmed person who serves as an
example for observational learning or vicarious
conditioning
Vicarious Desensitization
 Reduction in fear that takes place secondhand when a
client watches models perform the feared behavior
 Bandura: Observational learning
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Virtual Reality Exposure
 Presents fear stimuli to patients in a computerized
controlled fashion (ex: fear of flying in airplane)
Continuous Reinforcement: Reinforces the desired
response each time it occurs.
Advantageous for skill acquisition
Intermittent Reinforcement: Reinforces a response
only part of the time.
- Slower acquisition in the beginning, but shows greater
resistance to extinction later on.
- Used to strengthen established behaviors
- Usually necessary for the progression to naturally
occurring reinforcement
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Basic Schedules of Reinforcement
◦ Ratio (instances) and Interval (time
 Ratio schedules require a quantity of responses before
one response produces reinforcement
 Interval schedules require and elapse of (clock) time
before a response produces reinforcement.
◦ Fixed (specific) and Variable (unpredictable)
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Fixed Schedules
◦ With a fixed schedule, the response ratio or the
time requirement remains constant.
 Fixed Ratio 4 (FR 4) – Reinforcement is delivered after
every 4th correct response.
 Fixed Interval 2 min (FI 2) – Reinforcement is delivered
for the first response after the 2 minutes have elapsed.
◦ When you want Consistency of performance
 Produces a typical pattern of responding
 After the first response of the ratio requirement, subject
completes required responses with little hesitation
 Post reinforcement pause follows reinforcement
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Variable Schedules
◦ The response ratio or the time requirement can
change from one reinforced response to another.
◦ Variable Ratio – 5 (VR 5). An average of every 5th
correct occurrence
 Ex: Reinforce after the 2nd, 6th, 4th and 8th responses
◦ Variable Interval 2 minute (VI 2). Reinforcing the
first occurrence after an averaged elapsed time of 2
minute
 Ex: reinforce after 30 sec, 1 min, 4 min, 2.5 min
◦ Used to strengthen established behaviors
◦ Shows greater resistance to extinction later on
Fixed-ratio schedule: Reinforces a response only after
a specified quantity of responses.
 The faster the response, the more rewards
 Very high rate of responding
 Great for training, learning an association
 Often produces a post-reinforcement pause
Variable-ratio schedule: Reinforces a response after an
unpredictable quantity of responses.
 Produce consistent, steady response rates
 Excellent for maintaining behavior
 Very hard to extinguish because of
unpredictability
 Does not produce a post-reinforcement pause
Fixed-interval schedule: Reinforces only after the first
correct response following a specified time period.
 Slow to moderate rate of response
 Higher rate of responding toward end of interval
 Great for training, learning an association
 Often produces a post-reinforcement pause
Variable-interval schedule: Reinforces only after the first
correct response following an unpredictable time period.
 Produce constant, stable response rates
 Excellent for maintaining behavior
 Typically produces few hesitations between
responses
 Harder to extinguish because of unpredictability
 The larger the average interval, the lower the overall
rate of response
 Does not produce a post-reinforcement pause
Number of
responses
1000
Fixed Ratio
Variable Ratio
Fixed Interval
750
Rapid responding
near time for
reinforcement
500
Variable Interval
250
Steady responding
0
10
20
30
40
50
Time (minutes)
60
70
80
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Schedules of Differential Reinforcement of
Rates of Responding
◦ Provides an intervention for behavior problems
associated with rate of response.
◦ Variation of ratio schedules
◦ Differential reinforcement of high rates (DRH)
 Reinforcement of responses higher than a
predetermined criterion.
◦ Differential Reinforcement of Low Rates (DRL)
 Responses are reinforced only when they are lower
than the criterion.
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Progressive Schedules of Reinforcement
◦ Systematically thins each successive reinforcement
opportunity independent of the participant’s
behavior.
 Progressive Ratio Schedules of Reinforcement (PR)
 Progressive Interval Schedules of Reinforcement (PI)
◦ Using Progressive Schedules for Intervention
 Systematically increasing the ratio or interval
requirements for reinforcement
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Stimulus control occurs when
◦ The rate, latency, duration, or amplitude of a
response is altered
◦ In the presence of an antecedent stimulus
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Stimulus control is acquired when
◦ Responses are reinforced only in the presence of
a specific stimulus
 Known as the discriminative stimulus (SD)
◦ And not in the presence of other stimuli
 Known as stimulus deltas (S
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Stimulus Generalization
A tendency to respond similarly to stimuli that
are similar, but not identical to, a conditioned
stimulus
 If Bob was conditioned to answer the phone to a bell,
Bob will also respond to a buzzer or a tone
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Stimulus Discrimination
The learned ability to respond differently to
similar stimuli
 Bob has learned to answer the phone to a bell, answer
the door after a different bell, awaken after an alarm
clock bell
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Stimulus discrimination training
◦ Requires one behavior
◦ Two antecedent stimulus conditions (the SD and the
S )
Responses that occur in the presence of the SD
are reinforced (thus, the response increases in
the presence of the SD)
Responses that occur in the presence of the S
are not reinforced (this, the response decreases
in the presence of the S
◦ Can also result in a lesser amount or quality of
reinforcement
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Consistent use of reinforcers contingent upon
correct responding to the SD is critical
SD
Telephone rings
S
Doorbell rings
Response
Pick up
phone
and say
“hello”
Response
Pick up
phone
and say
“hello”
SR+
Friendly
conversation
SO
Friendly
conversation
withheld
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Stimulus generalization across all red objects
◦ Light red to dark red
◦ Different objects (car, ball, pencil)
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Stimulus discrimination between red and
other colors
◦ Red ball vs. yellow ball
◦ Red dress vs. blue dress
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Extinction is a procedure in which
reinforcement of a previously reinforce
behavior is discontinued; as a result,
occurrences of that behavior decrease in the
future.
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Extinction is a procedure that provides zero
probability of reinforcement
The effectiveness of extinction is dependent primarily
on the identification of reinforcing consequences and
consistent application of the procedure
Extinction does not require the application of aversive
stimuli to decrease behavior.
The extinction procedure does not prevent
occurrences of a problem behavior.
The environment is changed so that the problem
behavior will no longer produce the maintaining
consequences.
EO
SD
Response
SR+
Deprived of
water for a
long period of
time and
person has
history of
reinforcement
for getting
water when
turning the
“C” tap
Tap on
faucet
marked with
blue dot or
letter “C”
Turn tap
with blue
dot or “C”
Cold water
withheld
Let’s assume the tap is broken or
the water has been turned off to the
tap.
Turning tap
marked with blue
dot or “C” occurs
less often in the
future
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Procedural forms of extinction involve
“ignoring” the problem behavior.
Functional forms of extinction involve
withholding the maintaining reinforcers.
Applications of the procedural form of
extinction are often ineffective.
When the extinction procedure is matched to
the behavioral function, the intervention is
usually effective.
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Confusing forgetting and extinction
◦ In forgetting, a behavior is weakened by the
passage of time during which the individual does
not have an opportunity to emit the behavior.
◦ In extinction, behavior is weakened because it does
not produce reinforcement.
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Extinction of Behavior Maintained by Positive
Reinforcement
◦ Behaviors maintained by positive reinforcement
become extinct when those behaviors do not produce
the reinforcer.
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Extinction of Behavior Maintained by Negative
Reinforcement
◦ Behaviors maintained by negative reinforcement
(escape extinction) become extinct when those
behaviors do not remove the aversive stimulus
◦ Ex: The individual cannot escape from the aversive
situation.
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Extinction of Behavior Maintained by
Automatic Reinforcement
◦ Behaviors maintained by automatic reinforcement
are placed on extinction by masking or removing
the sensory consequence (sensory extinction)
◦ Not a recommended treatment option for problem
behavior, even self-stimulatory behaviors that are
maintained by social consequences or negative
reinforcement.
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Gradual Decrease in Frequency and
Amplitude
◦ Extinction produces a gradual reduction in behavior
◦ However, when reinforcement is removed abruptly,
numerous unreinforced responses can follow
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Extinction Burst
◦ An immediate increase in the frequency of the
response after the removal of the positive, negative,
or automatic reinforcement.
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Spontaneous Recovery
◦ The behavior that diminished during the extinction
process recurs even though the behavior does not
produce reinforcement
◦ Short-lived and limited if the extinction procedure
remains in effect.
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Resistance to Extinction
◦ Behaviors previously reinforced intermittently are
generally more resistant to extinction.
Extinction Burst
Before Extinction
(Reinforcement)
Responses
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During Extinction
Extinction Burst
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
Spontaneous Recovery
1
2
3
4
5
6
7
8
Time
9
10
11
12
13
14
15
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Number, Magnitude, and Quality of
Reinforcement
◦ The number of times a behavior produces
reinforcement may influence resistance to
extinction.
◦ A behavior with a long history of reinforcement may
have more resistance to extinction than a behavior
with a shorter history of reinforcement
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Number of Previous Extinction Trials
◦ Successive applications of conditioning and
extinction may influence the resistance to
extinction.
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Response Effort
◦ The effort required for a response apparently
influences its resistance to extinction.
 A response requiring great effort diminishes more
quickly during extinction than a response requiring
less effort.
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Identify and withhold all reinforcers maintaining the problem behavior
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Withholding reinforcement consistently (single most difficult aspect)
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Combining extinction with other procedures such as differential reinforcement and
antecedent procedures
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Using instructions
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Planning for extinction-produced aggression, replacement behaviors
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Increasing the number of extinction trials
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All individuals in contact with the learner must apply the same extinction procedure
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Guarding against unintentional extinction; do not extinguish good behaviors!
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Maintaining extinction: leave extinction procedures in effect permanently
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When not to use extinction
◦ If the behavior placed on extinction is likely to be imitated by others.
◦ If the behavior is extreme, harmful to self or others or very destructive to property , it
needs to be controlled with the most rapid and humane procedure available.
 Extinction as a singular intervention is not recommended in such situations.
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