1. Developing Behavioral Persistence Through the Use of Intermittent Reinforcement
Chapter 6

2. Definitions Schedule of reinforcement –
rule specifying which occurrences of a given behavior, if any, will be reinforced
Continuous Reinforcement (CRF):
every correct response is reinforced; fast learning & fast extinction
Intermittent Reinforcement:
only some correct responses are reinforced; slow learning & extinction

3. Definitions Acquisition phase Maintenance phase Free-Operant Procedure
behavior is being conditioned or learned
Maintenance phase
behavior has become well learned
Free-Operant Procedure
Individual is “free” to respond repeatedly
There are no constraints on successive responses
Discrete-Trials Procedure
Distinct stimulus is presented prior to an opportunity for a response to occur and be followed by reinforcement
Rate of responding is limited to the rate at which successive stimuli at the beginning of each trial are presented

4. Intermittent Reinforcement
Advantages
Reinforcer remains effective longer because satiation takes place more slowly.
Behavior that has been reinforced intermittently tends to take longer to extinguish.
Individuals work more consistently on certain intermittent schedules.
Behavior that has been reinforced intermittently is more likely to persist after being transferred to reinforcement in natural environment.

5. Ratio Schedules Based on number of responses emitted
Fixed-ratio (FR) schedule
Reinforcement occurs each time a set number of responses of a particular type are emitted.
Ratio strain – deterioration of responding from increasing an FR schedule too rapidly
Produce high steady rate of responding until reinforcement, followed by a post-reinforcement pause
The higher the value of the FR the longer the pause
Produce high rate of extinction

6. Ratio Schedules Variable-ratio (VR) schedule
The number of responses required to produce reinforcement changes unpredictably from one reinforcement to the next.
Produces a high steady rate of responding.
Also produces no (or at least very small) post-reinforcement phase
Differences between VR and FR schedules:
VR schedules can be increased more abruptly than FR schedules without producing ratio strain
Values of VR that can maintain a behavior are somewhat higher than FR
VR produces higher resistance to extinction that FR of same value

7. Simple Interval Schedules
Schedules are based in time
Fixed-Interval (FI) Schedule
The first response after a fixed amount of time following previous reinforcement is reinforced; new interval begins.
Size of FI schedule: amount of time that must elapse
No limit on how long after the end of the interval a response can occur in order to be reinforced
FI Schedules produce:
A rate of responding that increases gradually near the end of the interval until reinforcement
A post-reinforcement pause
Length depends on value of FI – the higher the value, the longer the pause

8. Simple Interval Schedules
Variable-Interval (VI) Schedule
The length of the interval changes unpredictably from one reinforcement to the next
Lengths of VI schedule vary around some mean value
Produces a moderate steady rate of responding and no post-reinforcement pause
Produces high resistance to extinction
Responding is lower during extinction after VI than after FR or VR

9. Simple Interval Schedules
Simple interval schedules are not often used because:
FI produces long post-reinforcement pauses
VI generates lower response rates than ratio schedules
Simple interval schedules require continuous monitoring of behavior after each interval until a response occurs

10. Interval Schedules with Limited Hold
Finite time after a reinforcer becomes available that a response will produce it.
FI/LH
VI/LH
Reinforcement in interval
No Reinforcement
First Response Reinforced

11. Limited Hold Short limited holds – similar results to ratio schedules
For small FIs, FI/LH produce results similar to FR schedules
Variable Interval, Limited hold – similar results to VR schedules
Used when want ratio-like behavior, but unable to count each instance of behavior

12. Duration Schedule
Reinforcement occurs after the behavior has been engaged in for a continuous period of time.
Fixed Duration (FD) – the period is fixed
Variable-Duration (VD) – interval changes unpredictably
Used only when target behavior can be measured continuously

13. Concurrent Schedules of Reinforcement
Schedules of reinforcement that are in effect at any given time
Herrnstein (1961) matching law:
The response rate or the time devoted to an activity in a concurrent schedule is proportional to the rate of reinforcement of that activity relative to the rates of reinforcement on the other concurrent activities.
Research findings on factors influencing choice of reinforcement:
Types of schedules that are operating
The immediacy of reinforcement
The magnitude of reinforcement
Response effort involved in different options

14. Pitfalls of Intermittent Reinforcement
Failure to conduct extinction correctly, may turn into intermittent reinforcement
Ex: Child tantrums – ignore first, but then give in

15. Guidelines for the Effective Use of Intermittent Reinforcement
Choose appropriate schedule for behavior you wish to strengthen
Choose schedule that is convenient to administer
Use appropriate instruments and materials to determine accurately and conveniently when the behavior should be reinforced
Frequency of reinforcement should initially be high enough to maintain desired behavior, then decrease gradually.
Inform individual of what schedule you are using.