Schedules of ReinforcementSchedules 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 Schedulesa. Fixed Interval (FI)b. Variable Interval (VI)

Cumulative Frequency GraphCumulative 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

Time

Response rate

Continuous Reinforcement Continuous Reinforcement (CRF)(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 ReinforcementIntermittent Reinforcement

• Reinforce some, but not all, desired responses

• Use to maintain established behavior

• Resistant to extinction

• Satiation less likely

Intermittent SchedulesIntermittent SchedulesRatio

• 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 SCHEDULESFIXED RATIO SCHEDULESUnder 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)

•Low to Moderate Response RateLow to Moderate Response Rate

•Poor Maintenance Under ExtinctionPoor Maintenance Under Extinction

•Post-Reinforcement PausesPost-Reinforcement Pauses

ConsiderationsConsiderations• Behavior must occur fixed number of times for Behavior must occur fixed number of times for

reinforcement reinforcement

• Larger ratio = ratio strain. If too large, student will cease Larger ratio = ratio strain. If too large, student will cease to engage in behaviorto engage in behavior

• Therefore, should not thin reinforcement abruptly from a Therefore, should not thin reinforcement abruptly from a dense schedule (e.g., CRF) to a very lean FR schedule. dense schedule (e.g., CRF) to a very lean FR schedule. Instead, proceed in smaller steps (FR 2, FR 4, etc.)Instead, proceed in smaller steps (FR 2, FR 4, etc.)

• Example: assembly line laborExample: assembly line labor

Example: FR20

SR+ every 20 words= 2 min on computer

STO - Given 20 basic first grade sight words on note cards, Jason STO - Given 20 basic first grade sight words on note cards, Jason will orally read the words within 1 minute with fewer than 5 errorswill orally read the words within 1 minute with fewer than 5 errors.

SR+

20 words read

VARIABLE RATIO SCHEDULESVARIABLE 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

High Rates of RespondingHigh Rates of Responding

Good Resistance to ExtinctionGood Resistance to Extinction

No Post-Reinforcement PausesNo Post-Reinforcement Pauses

Average number of times behavior occursAverage number of times behavior occurs

ConsiderationsConsiderations• Reinforcement can’t be predictedReinforcement can’t be predicted

• The more responses one makes, the more likely that The more responses one makes, the more likely that reinforcement will occurreinforcement will occur

• Therefore, supports high rates of responding with no post-Therefore, supports high rates of responding with no post-reinforcement pausesreinforcement pauses

• Because reinforcement can occur at any time, extinction Because reinforcement can occur at any time, extinction isn’t likelyisn’t likely

• Thinning from CRF to a lean VR schedule is easily Thinning from CRF to a lean VR schedule is easily accomplishedaccomplished

• Example: slot machineExample: slot machine

Example: VR6

SSR+R+ on average of every 6th hand on average of every 6th hand raise = puzzle with a peerraise = puzzle with a peer

STO - Given a teacher prompt to raise his hand during math seat STO - Given a teacher prompt to raise his hand during math seat work periods, Eric will raise his hand on 12 consecutive work periods, Eric will raise his hand on 12 consecutive opportunities across 5 math classes. opportunities across 5 math classes.

SR+ 9 hand raises9 hand raises

8 hand raises8 hand raises

5 5 hand hand raisesraises

2 hand raises2 hand raises

FIXED INTERVAL SCHEDULESFIXED INTERVAL SCHEDULESReinforcement 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)Post Reinforcement Pauses (scallops)

Low to Moderate Response RateLow to Moderate Response Rate

Poor Resistance to ExtinctionPoor Resistance to Extinction

SSR+R+ end of interval if behavior occurred or ASAP after end of interval if behavior occurred or ASAP after end of intervalend of interval

ConsiderationsConsiderations

• 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+ every 1 min= 1 min on computer

SR+

STO - Given the instruction to remain in his seat, Jason will be in his 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 seat each time the timer rings* on 20 of 30 opportunities for 5 consecutive sessions. *consecutive sessions. *set for 1 min intervalsset for 1 min intervals

VARIABLE INTERVAL SCHEDULESVARIABLE INTERVAL SCHEDULESVI 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)

Low to Moderate Response RateLow to Moderate Response Rate

No Post-Reinforcement PausesNo Post-Reinforcement Pauses

Best Resistance to ExtinctionBest Resistance to Extinction

ConsiderationsConsiderations

• 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+ on average every 5 minuteson average every 5 minutes

SR+

STO - During 35 minute reading activities without prompts, Jim STO - During 35 minute reading activities without prompts, Jim will be on-task for 30 consecutive minutes 4 classes in a row.will be on-task for 30 consecutive minutes 4 classes in a row.

Post-testPost-testWhich 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