Copyright © 2011 Pearson Education, Inc. All rights reserved. Changing the Control of a Behavior with Fading Chapter 9

Copyright © 2011 Pearson Education, Inc. All rights reserved.

Changing the Control of a Behavior with

FadingChapter 9


Fading

• Fading– Gradual change over successive trials of a stimulus that controls a response so that the response eventually occurs to a partially changed or completely new stimulus

– Process of slowly removing prompts after behavior is established


Fading

• Useful in a situation in which a stimulus exerts strong control of a response to be taught to occur to some other stimulus

• Advantages over trial and error procedures:1. Errors consume time2. If an error occurs, it tends to occur many

times, even though it is being extinguished

3. Nonreinforcement of errors (extinguishing of errors) produces emotional side effects


Dimensions of Stimuli for Fading

• Fading occurs along dimensions of stimuli

• Dimension – any characteristic that can be measured on some continuum

• Fading can occur across specific stimulus dimensions and across changes in general situation or setting– Ex: physical structure of room; number of other people present


Factors Influencing the Effectiveness of Fading

1.Choosing the final desired stimulus (FDS)– Stimulus that we want to evoke

or produce the behavior at the end of the fading procedure

– Important to select FDS in whose presence responding will be maintained in natural environment



2. Choosing the starting stimulus – prompt– Stimulus that reliably evokes the desired behavior

– Teacher behavior as prompts• Physical prompts/physical guidance – touching the learner to guide him appropriately

• Gestural prompts – pointing, making motions without touching, etc.

• Modeling prompts – demonstrating correct behavior

• Verbal prompts – verbal hints or cues– Environmental alterations as prompts

• Altering the physical environment to evoke desired response

– Extra-stimulus vs. within-stimulus prompts• Extra-stimulus – something that is added• Within-stimulus – alterations to discriminate



3.Choosing the fading steps:– Should be chosen carefully– Need to monitor performance to determine the speed of fading

– If student begins making errors, prompts may have been faded too quickly or with too few steps•May need to backtrack


Guidelines for Effective Application of Fading

1.Choose final desired stimulus2.Set an appropriate reinforcer3.Choose the starting stimulus

and fading steps4.Put plan into effect


Getting a New Behavior to Occur with Shaping

Chapter 10


Definition• Shaping

– Development of a new behavior by successive reinforcement of closer approximations and extinguishing preceding approximations of behavior

• Five aspects of behavior that can be shaped– Topography – specific movements involved– Frequency – number of instances that occur in a given period of time

– Duration – length of time a response lasts– Latency – time between occurrence of a stimulus and the response evoked by that stimulus

– Intensity – force of a response; physical effect the response has on the environment


Factors Influencing the Effectiveness of Shaping

• Specifying the final desired behavior– Terminal behavior – final desired behavior

– Specify precise behavior and conditions under which it is to occur

• Choosing a starting behavior– Should be a behavior that occurs often enough to reinforce within session time

– Should be a behavior that approximates the final desired behavior


Factors Influencing the Effectiveness of Shaping

• Choosing the shaping steps– Helpful to outline the approximations that will be reinforced

• Moving along at the correct pace– Reinforce an approximation at least several times before proceeding to the next step

– Avoid reinforcing too many times at any shaping step

– If behavior is lost because the program was moving too fast, or the steps were too big, return to an earlier approximation


Pitfalls of Shaping

• Shaping can be accidentally applied with unfortunate results– Harmful behaviors may be accidentally shaped

• Children may not get the necessary shaping to develop basic behaviors– E.g., developing speech


Guidelines for the Effective Application of

Shaping• Select the terminal or final desired behavior

• Select the starting behavior• Select an appropriate reinforcer• Develop the initial plan• Implement the plan

– Tell the learner about the plan before starting

– Begin reinforcing immediately following each occurrence of the starting behavior

– Never move to a new approximation until the previous one is mastered

– If learner stops working, they may have moved up the steps too quickly, steps may not be the right size, or the reinforcer may be ineffective

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Copyright © 2011 Pearson Education, Inc. All rights reserved. Changing the Control of a Behavior with Fading Chapter 9