Transcript Compound Schedules of Reinforcement

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Schedules of
Reinforcement
Chapter 13
What’s a Schedule?
• A schedule of reinforcement is a rule specifying…
– the arrangement and response requirements for
reinforcement
– e.g., whether a reinforcer follows every behavior, every
other behavior, etc.
• 2 Simple Schedules
– Continuous Reinforcement (CRF; FR1)
• The reinforcer follows every behavior
• CRF results in rapid acquisition (good for teaching)
• CRF produces little resistance to extinction
– Extinction (EXT)
• Discontinuation of a response-reinforcer contingency
Intermittent Reinforcement
•
•
Some rather than all responses are reinforced
Two main categories
– Ratio schedules: the reinforcer is delivered
after every X behaviors
– Interval schedules: the FIRST behavior
after X amount of time is reinforced
• Produces better resistance to extinction than
CRF
– Good for maintaining behavior
Ratio Schedules
•
•
2 Types: Fixed Ratio and Variable Ratio
Fixed Ratio: the reinforcer is delivered after a
fixed number of behaviors
– Designation: FR 5 (every 5th target response
is reinforced)
– Produces high-rate responding – why?
– Produces a post-reinforcement pause (PRP)
• PRPs are proportional to the size of the
ratio
– e.g., piecework
Fixed-Ratio Schedule of
Reinforcement
PRP
SR+ delivered
Variable Ratio
• The reinforcer is delivered after
an average number of behaviors
• Designation: VR 5
– 5, 4, 7, 6, 4, 3, 6, 7, 3
• Produces consistent, high rates
with no PRPs
• e.g., starting a lawn mower
• Clinical applications…
Tic-Tac-Toe VR Procedure
•
•
•
•
•
Teacher picks maximum number of
responses for an individual or group
(e.g., 30)
–
The smaller the #, the more likely it is
that the learner(s) will meet the
contingency
Learners fill in each square of tic-tac-toe
grid with a # no greater than the max
Teacher fills box with numbers on slips
of paper
–
Each number several times
Contingent on target behavior, student
picks slip of paper
–
If on tic-tac-toe, cross out number
Deliver SR+ when 3 in a row
27
5
23
11
15
9
3
20
10
Classroom Lottery VR Procedure
• Students write their names on index cards after
successfully completing assigned tasks
– Cards go in a box
• After a preset period of time (e.g., 1 week),…
– Teacher picks a card – that student is the winner
– The more cards earned, the more likely a student will be the
winner
Lottery
Box!
Considerations with Ratio
Schedules
• Both FR and VR schedules have 2 major
advantages
– Produce high rates of responding
– Easy to use
• Potential Disadvantage
– Ratio strain can result from abrupt increases in
ratio requirements
Interval Schedules
• 2 Types: Fixed Interval and Variable Interval
• Fixed Interval: the reinforcer is delivered for the
first target response after a fixed period of time has
elapsed
– Designation: FI 60s
– e.g., turning on the TV to watch your favorite
show
– Characteristics
• Produces PRPs, resulting in scallop or break-and-run
patterns
• Slow to moderate rate of responding
PRP
SR delivered
Variable Interval Schedule
• the reinforcer is delivered for the first behavior after
an average period of time has elapsed
– Designation: VI 60s
– produces steady, moderate responding (no
PRPs)
– e.g., checking e-mail
• Limited Hold: a feature that can be added to any
interval schedule
– The behavior must occur after the interval has
elapsed, but within a specific period of time
– Designation: FI 5 min LH 30 s
Considerations with Interval
Schedules
• Use if you want to produce low to moderate
response rates
• Advantage
– FI schedules are relatively easy to use with a
resetting timer
• Potential Disadvantage
– Off-task or other unwanted behavior may occur
during the PRP
FI scallop
Post-reinforcement pause
time
Thinning the Schedule of
Reinforcement
• Schedule thinning: Gradually increasing the
response ratio or the extent of the time interval
• Benefits
– The student’s behavior becomes more durable
(more resistant to extinction)
– More practical for caregivers to implement
• If you move too quickly, you can produce ratio strain
– Aggression
– Extinction of responding
• Not many guidelines are available to tell us how to do
this
LeBlanc, Hagopian,
Maglieri, & Poling (2002)
• Determine a reasonable terminal goal that’s
appropriate to the age and functioning level of the
learner
• Establish a series of steps between the initial value
and the terminal value
– 8-12 steps are recommended
– Increase 33% to 50% at each step
• Stay at one step at least 2 times
• If student is unsuccessful, go back a step
• Periodically probe a few steps ahead
LeBlanc et al.: Thinning from FR1
1
FR2
100%
2
FR4
100%
3
FR6
50%
4
FR9
50%
5
FR12
33%
6
FR16
33%
7
FR21
33%
8
FR28
33%
Differential Reinforcement of
Rates of Responding
• DRH: Reinforcement of responses higher than a
predetermined criterion (to produce a higher rate of
responding)
• DRL: Reinforcement of responses lower than a
predetermined criterion (to produce a lower rate of
responding)
• 3 Types
– Spaced-responding: reinforcement is only available for responses
separated by a given duration of time (IRT)
• Not used much b/c it’s difficult to calculate IRT
– Full session: reinforcement is delivered at the end of the session if the
total number of responses during the session was less than or more
than a criterion
– Interval: Total session is divided into equal intervals and reinforcement
is delivered at the end of each interval in which the number of
responses was less than or more than a criterion
Compound Schedules of
Reinforcement
• Combine different types of schedules
• Concurrent Schedules
• Discriminative Schedules
– Multiple Schedules
– Chained Schedules
• Nondiscriminative Schedules
– Mixed Schedules
– Tandem Schedules
Concurrent Schedules
• 2 or more contingencies of reinforcement operate
independently and at the same time for 2 or more
behaviors
• Used for
– Reinforcer Assessments
– Intervention Assessments
• Hanley et al. (2005) allowed individuals to choose which intervention they
preferred
– FCT + Punishment was preferred to FCT + Extinction
– Interventions
• Hoch et al. (2002) – boys with autism could play alone or with sibling
– Sibling was chosen when SR magnitude and quality were increased
• Use this when you can’t or shouldn’t treat inappropriate behavior directly
Multiple Schedule
• A type of discriminative schedule
• Two or more schedules are presented one
after another
– Each is correlated with a discriminative
stimulus
• Tiger and Hanley (2004)
– Different colored leis worn by the teacher were SDs
correlated with schedules of reinforcement for attention
FR1 Component (SD)
EXT Component (S∆)
FR 1
Mult FR 1 / EXT
Delay
to Sr
FR 1
Delay
to Sr
80
Frequency of Mands
15 s – 270 s
1 s – 60 s
5s–1s
60
40
20
Sr
EXT
0
Minimum 10
response criterion
20
30
40
Sessions
50
60
70
Chained Schedule
• A type of discriminative schedule
• Differs from multiple schedule:
– Schedules in the chain occur in the same order
– Behavior may be the same or different for each component
of the chain
– Conditioned reinforcement for the first element of the chain
is presentation of the second element
• The last response is reinforced with most powerful reinforcer
Nondiscriminative Schedules
• Mixed (like multiple schedule without the SDs)
– Tiger and Hanley (2004) – conducted the
same sessions without the teacher wearing
leis
• Tandem (like chained with out the SDs)
Use Caution…
• When extrapolating information about
schedules from basic research to applied
settings
– Most applications of schedules only approximate
lab schedules
– Many uncontrolled variables in applied settings will
influence a person’s sensitivity and insensitivity to
a schedule of reinforcement