PSYB45H3 Lecture : Lecture Note For Chapter 6, come and see
Chapter 6: Developing Behavioral Persistence through the use of intermittent Reinforcement
! Intermittent reinforcement refers to maintenance of behavior by reinforcing it only occasionally (i.e.
intermittently) rather than every time it occurs
• i.e. student is reinforced after a fixed number of responses had occurred therefore encouraging her to
work at a very steady rate
! Schedule of reinforcement: rule specifying which occurrences of a given behavior, if any, will be
reinforced
! Simplest schedule of reinforcement is continuous reinforcement (crf)
• Many behavior in everyday life are reinforced on a crf
! Opposite of crf is called extinction; on an extinction schedule no instance of a given behavior is
reinforced; effect is that the behavior eventually decreases to very low level or ceases altogether
! Between these two extremes lies intermittent reinforcement
! Any rule specifying a procedure for occasionally reinforcing a behavior is called an intermittent
reinforcement schedule
• Unlimited number of such schedules
• Because each produces its own characteristic behavior, different schedules are suitable for different
types of applications
• Certain schedules are more practical than others (e.g. some are more time consuming or labor intensive
than others)
! While a behavior is being conditioned or learned, it is said to be in the acquisition phase; after it has
become learned, it is said to be in the maintenance phase
! Usually its desirable to provide continuous reinforcement during acquisition and then to switch to
intermittent reinforcement during maintenance
! Intermittent schedules have several advantages over continuous reinforcement for maintaining behavior:
(a) The reinforcer remains effective longer because satiation takes place more slowly
(b) Behavior that has been reinforced intermittently tend to take longer to extinguish
(c) Individual work more consistently on certain intermittent schedules
(d) Behavior that has been reinforced intermittently is more likely to persist after being transferred to
reinforcers in the natural environment
! The 4 types of intermittent schedules for increasing and maintaining behavior: ratio, simple interval with
limited hold and duration; each is subdivided into fixed and variable, giving 8 basic schedules
! Free-operant procedures is one in which the individual is “free” to respond repeatedly, in the sense that
there are no constraints on successive responses
• e.g. in Jan’s math class, when Jan was given a worksheet containing a number of arithmetic problems to
solve, Jan could have worked at various rates
! 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
• e.g. if Jan’s teacher presented a math problem and waited a brief time for Jan to solve it, following
which another problem was presented to Jan and so on, then this would be a discrete trial procedure
Ratio Schedules
! Fixed-ratio (FR) schedule: reinforcement occurs each time a set number of responses of a particular
type are emitted
• Schedule increased in steps
• If steps are not taken then behavior might be deteriorated and appear as though it were on extinction
• This deterioration of responding from increasing FR schedule too rapidly is sometimes referred to as
ratio strain
• Optimal response requirement differs for different individuals and for different tasks
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• Higher the ratio at which an individual is expected to perform, the more important it is to approach it
gradually through exposure to lower ratios
• Optimal ratio value that will maintain a higher rate of response without producing ratio strain must be
found by trial and error
• FR schedules, when introduced gradually, produce a high steady rate until reinforcement, followed by a
post-reinforcement pause
• Length of post-reinforcement pause depends on the value of FR- higher the value, longer the pause
• FR schedule also produces higher resistance to extinction
! Examples: football coach telling team to do 20 push ups- that would be FR 20; paying an industrial
worker for a specified number of completed parts (called piece-rate pay)
! Variable-ratio (VR) schedule: number of responses required to produce reinforcement changes
unpredictably from one reinforcement to the next
• Number of responses required for each reinforcement varies around some mean value, and this value is
specified in the designation of that particular VR schedule
• Like FR, it produces a high steady rate of responding; produces no (or at least a very small) post-
reinforcement pause
! E.g. Salesperson can never predict exactly when a sale will occur and is likely to continue making
house calls right after a sale
• Difference b/w FR and VR: VR schedule can be increased somewhat more abruptly than an FR
schedule without producing ratio strain, the values of CR that can maintain responding are somewhat
higher than FR and VR produces a higher resistance to extinction than FR schedules of the same value
• Examples of VR schedules in natural environment: asking some1 for a date; slot machines"
unpredictable events; can’t guess what will happen
! Ratio schedules are used when one wants to generate a high rate of responding and can monitor each
response (since it is necessary to count the responses in order to know when to deliver reinforcement on a
ratio schedule)
! FR is more commonly used than VR in behavioral programs because it is simpler to administer
! Ratio schedules studied in discrete-trials procedures: task designed to teach children with developmental
disabilities to make pictures of objects
• Procedures involves presenting a carefully designed sequence of trials in which the teacher sometimes
speaks the name of the picture for the child to imitate and sometimes requires that the child name the
picture correctly; correct responses are reinforced with praise and a treat; and children make more
correct responses and learn to name more pictures when correct responses are reinforced with a treat on
a ratio schedule then when they are continuously reinforced with a treat
! This is only if the ratio schedule does not require too many correct responses per reinforcement
! As response requirement increases, performance improve at first but then begins to show ratio strain
Simple Interval Schedule
! Fixed interval (FI) schedule: first response after a fixed period of time following the previous
reinforcement is reinforced and a new interval begins
• All that is required for reinforcement to occur is that the individual engage in behavior after
reinforcement has become available because of the passage of time
• Size of FI is amount of time that must elapse before reinforcement becomes available (e.g. if one minute
must elapse before behavior can be reinforced, we call the schedule an FI one-minute schedule
• Although the passage of a certain amount of time is necessary for reinforcement to occur, a response
must occur sometime after the specified interval; no limit on how long after the end of the interval a
response can occur in order to be reinforced
• Response occurring before the specified interval is up has absolutely no effect on the occurrence of the
reinforcer
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Document Summary
Chapter 6: developing behavioral persistence through the use of intermittent reinforcement. schedule of reinforcement: rule specifying which occurrences of a given behavior, if any, will be reinforced. simplest schedule of reinforcement is continuous reinforcement (crf: many behavior in everyday life are reinforced on a crf. opposite of crf is called extinction; on an extinction schedule no instance of a given behavior is reinforced; effect is that the behavior eventually decreases to very low level or ceases altogether. between these two extremes lies intermittent reinforcement. while a behavior is being conditioned or learned, it is said to be in the acquisition phase; after it has become learned, it is said to be in the maintenance phase. usually its desirable to provide continuous reinforcement during acquisition and then to switch to (a) (b) (c) (d) intermittent reinforcement during maintenance. Intermittent schedules have several advantages over continuous reinforcement for maintaining behavior:
