Schedules of Reinforcement
There are several alternate ways to arrange the delivery of
reinforcement
A. Continuous reinforcement (CRF), in which every appropriate
response is reinforced
B. Intermittent schedules of reinforcement, in which reinforcement
is unpredictable. There are two sub-categories of intermittent
reinforcement schedules.
1. Ratio Schedules
a. Fixed Ratio (FR)
b. Variable Ratio (VR)
2. Interval Schedules
a. Fixed Interval (FI)
b. Variable Interval (VI)
Cumulative Frequency Graph
• Used to illustrate the effects of
different schedules of
reinforcement
• Each response is added to the
previous one(graphed
cumulatively)
• The steeper the slope of the
data path, the more rapid is
the rate of responding
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Time
Continuous Reinforcement
(CRF)
• Use during acquisition
stage of learning
• Reinforce each
occurrence of desired
behavior
• Low resistance to
extinction (behavior
doesn’t persist when
reinforcement is withheld
• Risk of reinforcer
satiation, esp. with
primary reinforcement
Intermittent Reinforcement
• Reinforce some, but not all, desired
responses
• Use to maintain established behavior
• Resistant to extinction
• Satiation less likely
Intermittent Schedules
Ratio
• Reinforcement based on
number of responses
√ Fixed (FR)
FR 10--every 10th correct
response is reinforced
√ Variable (VR)
VR 10--on average, every
10th correct response is
reinforced
Interval
• Reinforcement based on
passage of time
√ Fixed (FI)
FI 2min.--1st correct
response after passage
of 2 min. reinforced
√ Variable (VI)
VI 2min.--1st correct
response after an
average of 2 min. has
passed is reinforced
FIXED RATIO SCHEDULES
Under fixed ratio schedules, the reinforcement is
contingent on a set (fixed) number of responses.
(FR-2, FR-4, FR-17)
FR schedules result in a high rate of responding, with
pauses after reinforcement. Increasing the ratio
results in longer pauses.
FIXED RATIO (FR)
•Post-Reinforcement Pauses
•Low to Moderate Response Rate
•Poor Maintenance Under Extinction
Considerations
• Behavior must occur fixed number of times for
reinforcement
• Larger ratio = ratio strain. If too large, student will cease
to engage in behavior
• Therefore, should not thin reinforcement abruptly from a
dense schedule (e.g., CRF) to a very lean FR schedule.
Instead, proceed in smaller steps (FR 2, FR 4, etc.)
• Example: assembly line labor
Example: FR20
SR+
20 words read
SR+ every 20 words= 2 min on computer
STO - Given 20 basic first grade sight words on note cards, Jason
will orally read the words within 1 minute with fewer than 5 errors.
VARIABLE RATIO SCHEDULES
On a VR schedule (VR-3, VR-10, VR-200) reinforcement may
come at any time. On the average, however reinforcement
comes after so many responses.
VR reinforcement results in high steady response rates.
Extinction usually results in a high number of responses in a short
time. Responses come as rapid bursts of behavior, followed by
increasing pauses and then abrupt cessation of responding.
VARIABLE RATIO
No Post-Reinforcement Pauses
High Rates of Responding
Good Resistance to Extinction
Average number of times behavior occurs
Considerations
• Reinforcement can’t be predicted
• The more responses one makes, the more likely that
reinforcement will occur
• Therefore, supports high rates of responding with no postreinforcement pauses
• Because reinforcement can occur at any time, extinction
isn’t likely
• Thinning from CRF to a lean VR schedule is easily
accomplished
• Example: slot machine
Example: VR6
9 hand raises
SR+
2 hand raises
8 hand raises
5
hand
raises
SR+
on average of every 6th hand raise =
puzzle with a peer
STO - Given a teacher prompt to raise his hand during math seat
work periods, Eric will raise his hand on 12 consecutive
opportunities across 5 math classes.
FIXED INTERVAL SCHEDULES
Reinforcement under a fixed interval schedule is
contingent on a correct response that occurs after the
passage of time (FI-20 sec., FI-2 min., FI-1 hr.)
On a FI schedule, the first correct response after a fixed
length of time is reinforced. This results in scalloping-pauses after reinforcement with increased responding
at the end of the interval.
FIXED INTERVAL (FI)
Post Reinforcement Pauses (scallops)
Low to Moderate Response Rate
Poor Resistance to Extinction
SR+ end of interval if behavior occurred or ASAP after
end of interval
Considerations
• Reinforcement at end of interval if
behavior occurred in that interval, or as
soon as the behavior occurs after the
interval has expired
• Extinction occurs if schedule is thinned too
quickly (post-reinforcement interval is too
long)
• Example: waiting for bus
FI1 Min.
SR+
SR+ every 1 min= 1 min on computer
STO - Given the instruction to remain in his seat, Jason will be in his
seat each time the timer rings* on 20 of 30 opportunities for 5
consecutive sessions.
*set for 1 min intervals
VARIABLE INTERVAL SCHEDULES
VI reinforcement results in sustained responding at a
low rate. The reinforcement is contingent on the first
correct response that occurs after an interval
averaging a certain length of time (VI-20 sec., VI-3
min., VI-2 hr.)
Extinction after interval schedules of reinforcement
results in low, sustained responding that gradually
tapers off. Extinction on interval schedules takes
longer than it does on other schedules.
VARIABLE INTERVAL (VI)
No Post-Reinforcement Pauses
Low to Moderate Response Rate
Best Resistance to Extinction
Considerations
• Relatively low but stable response rate
• No post-reinforcement pauses, because
intervals between reinforcement are not
predictable
• Most resistance to extinction of any
schedule
• Example: timer game to promote in-seat
behavior
Example: VI5
SR+
SR+ on average every 5 minutes
STO - During 35 minute reading activities without prompts, Jim
will be on-task for 30 consecutive minutes 4 classes in a row.
Post-test
Which schedules:
• Result in high rates of behavior?
• Result in low rates of behavior?
• Result in pauses in responding?
• Result in steady responding?
• Are best for acquisition of behavior?
• Are best for maintenance of behavior?
• Lead to most rapid extinction?
Answers
•
•
•
•
Ratio schedules result in high rates of responding
Interval schedules result in low rates of responding
Fixed schedules result in pauses in responding
Variable schedules result in steady responding
FR
VR
FI
VI
• A CRF schedule is best to use during the acquisition
of a behavior
• An intermittent schedule is best to use to maintain an
established behavior
• Extinction is most rapid on a CRF schedule