Principles of Behavior
Sixth Edition
Richard W. Malott
Western Michigan University
Power Point by Nikki Hoffmeister
Chapter 17
Ratio Schedules
What is a Schedule of
Reinforcement?
Schedule of Reinforcement:
• The way reinforcement occurs
• because of the number of responses,
• time between responses,
• and stimulus conditions.
What is Continuous
Reinforcement?
Continuous Reinforcement (CRF):
• A reinforcer follows each response.
Intermittent Reinforcement:
• Reinforcement occurs, but not after
each response.
When should you use CRF?
• Continuous reinforcement is usually best
for shaping or maintaining difficult
behavior.
– Shaping vocal responses
What is a Fixed-Ratio Schedule?
Fixed-Ratio (FR) Schedule of
Reinforcement:
• A reinforcer follows
• a fixed number of responses.
What kind of responding does a
fixed-ratio schedule produce?
Fixed-Ratio Responding:
• After a response is reinforced,
• no responding occurs for a period of time,
• then responding occurs at a high, steady
rate
• until the next reinforcer is delivered.
Non-Cumulative Graph
Non-Cumulative Graph
• The horizontal line (x-axis) indicates the
passage of time
• Each vertical line indicates a response
• At the end of each ratio of 8 responses a
reinforcer is delivered (indicated by star)
• After each star, the line is flat, indicating
no response occurs for a while
– Post-reinforcement pause
Post-Reinforcement Pause
• Characteristic of fixed-ratio-maintained
behavior
• The length of the pause is proportional to
the size of the ratio
High Ratios
• If you wish to establish a high ratio
requirement,
• you need to do so gradually,
• raising the ratio from 2 to 4 to 6 responses
and up.
• Otherwise the response may extinguish.
What is the general rule for
establishing intermittently
reinforced behavior?
• First, use continuous reinforcement
• and gradually increase the intermittency of
reinforcement
• as responding stabilizes at a high rate.
The Cumulative Graph
Cumulative Graph
• Behavior analysts often use this type of
graph when studying schedules of
reinforcement.
• The vertical axis (ordinate) is labeled
cumulative frequency of responses as
opposed to a non-cumulative graph in
which the ordinate is labeled responses.
• The post-reinforcement pause is where
the slope of the line is zero.
What is a Variable Ratio Schedule?
Variable-Ratio (VR) Schedule of
Reinforcement:
• A reinforcer follows
• after a variable number of responses.
What type of responding does a VR
schedule produce?
Variable-Ratio Responding:
• Variable-ratio schedules produce
• a high rate of responding,
• with almost no post-reinforcement
pausing.
VR Schedules
• VR 50
– This means that a reinforcer is delivered after
an average of 50 responses
– An FR 50 means the reinforcer is delivered
after exactly 50 responses
• Intermittent Reinforcement:
– Generic term that includes both fixed and
variable ratio schedules
Reinforcer vs. Reinforcement
• What is a specific pellet of food for a
deprived rat?
– A reinforcer
– Reinforcement
• The immediate delivery of a pellet
contingent on a deprived rat’s lever press
with a resulting increased rate of
pressing?
– Reinforcer
– Reinforcement
Reinforcer vs. Reinforcement
• What is a quarter for a deprived
professor?
– Reinforcer
– Reinforcement
• What is the immediate delivery of a
quarter, contingent on a deprived prof’s
pleading for a raise, with a resulting
increased rate of pleading?
– Reinforcer
– Reinforcement
Ratio Schedules in Everyday Life
• Are slot machines in casinos examples of
everyday VR schedules?
• No; there are 5 reasons why
4 Reasons Why Slot Machines are
Not VR Schedules
1. It’s loaded with learned reinforcers in
addition to the silver dollars
•
•
Like those fruits that appear in the window,
one after the other
You get 2 cherries in a row…a big reinforcer
4 Reasons Why Slot Machines are
Not VR Schedules
2. The variable amount of the reinforcer you
get at the end of the so-called VR
•
•
•
Sometimes you get only one silver dollar
Sometimes it’s 10, 18, so on
None of that’s like the ratios the behavior
analysts study in the Skinner box
4 Reasons Why Slot Machines are
Not VR Schedules
3. The size of the ratio is much smaller than
is typical in the Skinner box of the
professional research lab
•
•
Like a VR 100
In a casino, people would not play if
machines had ratios of 100
4 Reasons Why Slot Machines are
Not VR Schedules
4. The emotional reaction is itself
reinforcing
•
Near misses are reinforcing
Intermediate Enrichment
• Free-operant procedures
– Most Skinner-box research involves freeoperant responding
– The animal is free to respond at various
frequencies (1 lever press per minute to 100
lever presses per minute)
– There is no S∆ after each response, so there
is no inter-trial interval between each
response and the next SD
Discrete-Trial Procedure
•
•
•
•
•
There is an SD,
a single response,
and an outcome,
followed by an S∆ (intertrial interval);
then the next trial starts.
In the Classroom:
Discrete-Trial Procedure
SD: Sue says, “Jimmy point to the horse.”
Response: Jimmy points to the horse.
Outcome: Sue says, “Good boy, Jimmy.” (a
learned reinforcer for Jimmy)
S∆ (Inter-trial Interval): Sue says nothing
In the Classroom:
Free-Operant Procedure
SD: Sue and Jimmy at the snack table.
Response 1: Jimmy says, “Juice please.”
Outcome: Sue gives him a sip of juice.
Response 2: Jimmy says, “Juice, please.”
Outcome: Again, Sue gives him a sip of
juice.
S∆: Sue and Jimmy leave the snack table.
Discrete Trial vs. Free Operant
Discrete Trial
Free Operant
Is there an SD
and an S∆?
Yes
Sometimes
Is there an
inter-trial
interval?
The measure
is…
Yes
Usually not
Latency or
accuracy
Rate
Advanced Enrichment
• Hybrid Discrete-Trial/Free-Operant
Procedure
– Each free-operant response, itself, consists of
a discrete trial.
Example
• Sue and Jimmy are in the structured-play area
Response 1: Jimmy picks up a piece of the puzzle
and puts it in the puzzle form
Response 2: Jimmy picks up a 2nd piece and puts
it in the puzzle form
Response 3: Jimmy picks up a 3rd, final piece,
and puts it in the form
Outcome: Jimmy has completed the puzzle and
sees a picture of Barney. Sue says, “Good job.”
Why Hybrid?
• This is an example of a discrete trial,
because each piece Jimmy puts in the
puzzle is an SD for the next response.
• It is also an example of free operant
because Jimmy is free to place each
puzzle piece as fast as he “wants,” and…
• A measure of his behavior would be a rate
measure (e.g., 8 pieces per minute).
On DickMalott.com
• Chapter 17 Advanced Enrichment Section
– In Search of the Everyday Variable Ratio
Join us for Chapter 18:
Interval Schedules