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

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 S D

Discrete-Trial Procedure There is an S D, a single response, and an outcome, followed by an S ∆ (intertrial interval); then the next trial starts.

In the Classroom: Discrete-Trial Procedure S D : 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 S D : 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 TrialFree Operant Is there an S D and an S ∆ ? YesSometimes Is there an inter-trial interval? YesUsually 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 2 nd piece and puts it in the puzzle form Response 3: Jimmy picks up a 3 rd, 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 S D 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