principles of behavior sixth edition richard w. malott western michigan university power point by...

Principles of BehaviorSixth Edition

Richard W. MalottWestern 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 free-

operant 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?

Yes Usually not

The measure is…

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