Common skill acquisition procedures: differential reinforcement, shaping, prompting and fading, chaining.

By the end of this article, you will be able to complete the following:

You are viewing: Which Of The Following Is An Example Of Shaping Frequency

• Define shaping

• Describe how to shape behavior

• State the difference between response prompts and stimulus prompts

• Give examples of response prompts and stimulus prompts

• Explain how to fade prompts using most-to-least, least-to-most, or time delay procedures.

• Define and describe a behavior chain.

• Describe and identify a correct task analysis.

• Write a task analysis.

• Describe how to teach a chain of behaviors using any of the three chaining methods: forward, backward, and total task presentation.

Key terms and Concepts

Very similar to project management, but for a behavior project.

* differential reinforcement

* shaping

* stimulus prompt

* response prompt

* prompt fading

* behavior chain

* forward chain

* backward chain

* task analysis

Let’s learn how to teach behavior and gain stimulus control.

#DifferentialReinforcement

Differential reinforcement is defined as reinforcing only those responses that meet a specific criterion and placing all other responses in extinction.

This means that when you differentially reinforce, you are only reinforcing certain behaviors (or certain target approximations of a behavior). It is a key part of a procedure known as shaping. Let’s learn about shaping and how it is done.

#Shaping

Shaping is a procedure or method for teaching new skills (teaching behaviors that are not in the person’s repertoire or that the person does not engage in independently).

The definition of shaping is the differential reinforcement of successive approximations of a target behavior. So, basically, you reinforce (and let other behaviors extinct) only the steps taken towards achieving the goal behavior.

Behaviors can be shaped through a number of dimensions including topography, duration, latency, rate, force. Here are all of the steps to implementing a shaping program:

1. Select and define a behavior to improve across some dimension – typically this is determined from baseline data collected on some behavior over some dimension of the behavior.

2. Establish the initial approximation and the target approximation. This allows you to identify when the program is mastered.

3. Ensure shaping is the correct procedure. If the terminal behavior occurs, even if intermittently, then shaping is not required. In this case, consider applying differential reinforcement to increase the frequency with which it occurs.

4. Choose the shaping steps, where each step is a closer and closer approximation to the target response.

5. Identify the reinforcer that you are going to use, it must be easily and immediately delivered following the behavior – typically a preference assessment can be helpful here.

6. When introducing the initial approximation, provide differential reinforcement contingent on the quality and independent of the first approximation.

7. Once the learner is demonstrating mastery of the initial approximation, place it on extinction while moving through the next steps.

8. Differentially reinforce better quality responding for better quality approximations.

9. Continue to use this process until the target approximation is met.

Here is an example of shaping. The goal here is to shape the duration of on-task behavior.

Before you run the program:

• You are working with a girl named Sara. Your baseline data shows that she stays on task at an activity for three minutes on average.

• Your BCBA decides that the target for on task behavior at an activity is 10 minutes.

• You run a preference assessment with Sara and choose access to a mini trampoline as the reinforcer. The reference assessment shows that it is a highly preferred and will likely function as a reinforcer.

Let the shaping begin!

• The first time you run the program, you provide Sara with access to the trampoline after she has remained on task for three minutes.

• After Sara has successfully met the three-minute criterion three times in a row, you move to the next approximation. Now Sara must remain on task for four minutes before moving to the trampoline.

• Once Sara has managed this three times in a row, you will increase the expectation to five minutes.

This is how shaping works. Once the person has met the criteria for an approximation of the target behavior, we increase our expectations and move on to the reinforcing the next target approximation.

So, how large should the changes in approximations be and how long does one stay there for?

Let’s consider each separately:

In regard to determining changes in approximations, there are no set guidelines. You will need to use clinical judgement. You don’t want to make the differences in approximations too big, or the person will potentially not be able to successfully complete the next approximation. On the other hand, if the differences between the approximations are too small, the shaping program will get dragged out for a long time.

In regard to how long you should stay at each step, again, it’s a fine balance. You don’t want to move too quickly through the approximations as you want to ensure that the person has truly mastered each step. On the other hand, you also have to avoid staying too long at any particular approximately that the shaping procedure is not unduly long.

#Prompting

Now on to prompting.

Sometimes you will teach a behavior that a person can already do or do a part of, but they may not do it at the right time or in the right situations. You may then use prompting to increase the chance that the person will engage in the correct behavior at the right time and in the right situation.

So, what are prompts? Prompts are supplementary stimuli used to evoke behavior in the presence of an EO or Sd that will (hopefully) eventually gain stimulus control over the behavior. In the text, Milterberger writes that a prompt may involve the therapist (response prompt) or supplemental environmental stimuli (stimulus prompt).

Here is an example of a prompt;

When john comes inside from recess, he usually is shouting to his friends. He does not use his quiet indoor voice. However, Johnny will use a quit indoor voice when his teacher tells him to do so. Whenever he enters the classroom from recess, his teacher tells Johnny to use his indoor voice.

Behaviourally speaking, Johnny’s talking in a quiet voice behavior is not under stimulus control of being inside. Or, inside is not an Sd for talking in a quiet voice for Johnny. This behavior is under stimulus control of the teacher’s reminder. The reminder is functioning as a prompt and the behavior is not under the natural stimulus control of the inside setting.

There are different methods, but most fall in two categories:

• Response prompts

• Stimulus prompts

#Responseprompts

the following are types of response prompts and how they would be implemented or used:

• Verbal

• Gestural

• Modelling

• Physical

#VerbalPrompts

consists of giving someone an instruction. Remember our earlier example with Johnny and his teacher, who prompted him to use his indoor voice saying, remember to use your indoor voice Johnny. This is an example of a verbal prompt.

#GesturalPrompts

consist of making a motion to prompt the desired behavior. So, again thinking of Johnny, maybe the teacher could avoid a verbal prompt and just put her finger to her lips to remind Johnny to use his indoor voice. This would be an example of a gestural prompt.

#ModelingPrompts

A prompt that constitutes having another person demonstrate the desired behavior. Looking at our example with Johnny, if the teacher or another student walked in the school door and changed her voice volume as she did so, this would be an example of modelling. The hope would be that Johnny would then imitate the model.

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Modeling is a very powerful method of prompting, and is used extensively in teaching in ABA. Most people learn at a very early age to imitate others, and thus they quickly learn to do things that others do, simply through imitation. In fact, imitation is such an important method of learning that if a child does not show a tendency to imitate the behavior of others, as is sometimes the case with children with autism, one of the first learning goals includes teaching the child to imitate. Why? Because being able to imitate not only allows us, as therapists, to teach a wide range of skills, but also provides the learner with the skill necessary to learn from natural models in the environment.

#PhysicalPrompts

Or Physical Guidance, may be used to prompt motor behavior.

For example, if you were teaching a person to complete a puzzle, you may physically direct his hand to the puzzle piece and guide his fingers to pick the piece.

Physical prompts in which a person’s hand is guided to do the correct response are often called hand-over-hand prompting. It is possible to use a full physical prompt – in which the person’s movements are only partially guided.

#StimulurPrompts

Stimulus prompting involves “some change in an antecedent stimulus or the addition or removal of an antecedent stimulus, with the goal of making a correct response more likely” (milternberger).

This means that you alter the stimulus that you would like to have become an Sd. You can do that by changing or highlighting the Sd (within-stimulus prompting) or adding (or removing) something to the Sd (extrastimulusprompting).

#Within stimulus involves altering some aspect of the Sd itself to make it more likely that the person will respond to it.

For example, if the person you are working with has a hard time remembering to hang up her coat after coming in, her coat hook could be painted bright pink (which happens to be her favorite colour) in order to make it more salient and more likely that she will hang her coat up on it.

One common within stimulus prompt used is positional prompting in which the stimulus the person should respond to it is set closer to her.

Here is another example. The target response is pointing to the picture of the dog. Notice that the picture of the dog has been made much bigger, and hence, more salient than the other two pictures. The person will be more likely to point to that picture when asked to point to the dog.

#Extra stimulus prompting involves adding something extra to the Sd to make it more likely that the person will respond the correct way. For example, a teacher is placing an X on the right hand of a child who has difficulty discriminating his left hand from his right one. Over time, the X faded and the child continued to be able to make the correct discrimination.

#Choosing Prompts

When choosing prompts, you generally have several options open to you.

In general, it is best to choose the least intrusive prompts that will still be effective. If you are not sure which prompt will work, try a less intrusive prompt first. If it does not work, try a more intrusive prompt.

Choose the prompt that will allow the person to focus on the Sd. Remember that the ultimate goal is for the behavior to be under the stimulus control of the Sd and not the prompt.

#Transferring stimulus control from response prompts

When you use promtps, you can get the desired behavior to occur. However, your work is not done, yet.

The behavior is under stimulus control of the prompt. It is now important to get rid of the prompt. If you don’t, the person will remain what is called prompt dependent.

Achieving stimulus control is done through prompt fading. Prompt fading is the process of transferring stimulus control from the prompt to the natural Sd. There are many ways for prompts to be faded.

#Most-to-least fading also known as decreasing assistance is a method in which the first prompt given is usually strong enough to ensure that the desired behavior will occur.

When the person is reliably successful at the prompt level, the therapist then moves to a less intense or milder form of prompting. This continue until the individual can do the behavior with no prompt at all.

It is beneficial to know that this type of fading can be done with the same type of prompt. This means that you can give less and less of the same type of prompt – for example, if you were physically prompting a person to pick up their backpack, you could start with a full physical prompt (hand over hand with enough intensity to ensure they picked up the bag) and fade your prompt by using less and less you hand on their hand or less and less intensity.

Prompts can also be faded across different types of prompts. You can give a very intrusive prompt (like a physical prompt), then fade back to a less intrusive prompt (like a gestural prompt) and then eventually to no prompt.

An example of this:

The initial prompt given to help a person get their cereal might say with the verbal request (the eventual Sd) Go get your cereal. This could be accompanied by the therapist placing their hand on the person’s elbow and leading them to the cereal on the counter, followed by the therapist giving hand-over-hand prompt to pick it up.

Once the person has been successful at this level of prompting, then the therapist could fade the prompt so that just their hand touched behind the person’s elbow, a small tap pushing the person’s hand to the cereal. Again, as the person continues to be successful at complying with this instruction, the therapist might fade the prompt to a simple pointing gesture; eventually, even the gesture could be faded out.

When most-to-least promoting is used skillfully, it can result in nearly errorless learning. With errorless learning, the prompt level is carefully gauged so that it decreases the chance that the person makes an incorrect response.

#least-to-most fading also known as increasing assistance is a fading method that is the reverse of most-to-least. To begin with, a very mild prompt is given. If the individual does not response, then a stronger prompt is immediately given. If the individual does not respond, the prompt strength is increased again until the correct response is made.

The goal of least-to-most prompting is that the individual learns to respond to the Sd, as this leads to quick access to the reinforcer and avoidance of the prompts.

#TimeDelay differs from other fading procedures since the type of prompt does not change, but rather the time taken to give the prompt is increased. This is very simple:

– The Sd is delivered

– A few seconds pass (about 2 to 10 seconds so that the person does not get frustrated)

– The prompt is delivered

– When the individual makes the correct response, a reinforcer is delivered.

The idea is that the person will learn to avoid the delay by responding before the prompt comes.

Time delay is often used in trying to get children to use signs spontaneously.

#transferring stimulus control from stimulus prompts

When stimulus prompts are used, the Sd is altered or highlighted in some way to help the person make a correct discrimination. When the stimulus prompt is gradually changed back to its original form until the person can respond correctly, this is called stimulus fading.

Here is an example:

This is an example of using extra-stimulus prompts to teach word recognition.in this example, we see how the extra-stimulus prompt of coloring the word “red” the color red is faded gradually until the word itself becomes the Sd and not the color.

#behaviorchains

Some behaviors that we are interested in teaching are actually complex chains of behavior. For example,

Washing hands involves

– turning on the tap

– wetting your hands

– putting soap on your hands

– rinsing your hands

– turning off the tap

– drying your hands

Each of these steps are like links in the chain of behavior called washing hands.

Behavior chains are complex behaviors consisting of two or more component behaviors that occur together in sequence.

Chains of behaviour end in reinforcement. The natural reinforcer for hand washing is having clean hands. A chain of behaviour is comprised of a series of Sds and responses, which end in a reinforcer:

Hand washing:

– Sd1 (dirty hands) – R1 (turn on tap)

– Sd2 (running water) R2 (put hands under the tap)

– Sd3 (wet hands) – R2 (rub soap on hands)

– Sd4 (soapy hands) R4 (rinse hands under tap)

– Sd5 (wet clean hands and water running) R5 (turn off tap)

– Sd6 (wet clean hands and no water running) – R6 (dry hands on towel)

– = reinforcer clean dry hands.

Brushing teeth

– turn on right (cold) tap

– pick up your toothbrush

– put toothbrush under water for five seconds so that all bristles are wet

– turn off water

– pick up toothpaste tube

– unscrew toothpaste cap

– squeeze toothpaste tube to put on enough toothpaste to cover the top of bristles

– bring toothbrush to your mouth

– move toothbrush back and forth in mouth – this can left up to personal opinion but it would probably look something like: move back and forth for 10 seconds on left side, move back and forth for 10 seconds on right side, open mouth and rub back and forth for 10 seconds on top of teeth, etc. – all of these would be separate steps in the chain

– rinse toothbrush

– put toothbrush in holder

– turn on tap

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– fill cup

– drink water and swish it around in mouth

– spit water in sink

– put away cup

We can see, task analysis can become long depending how small we separate the steps. However, it is always a good idea to make a task manageable and suited to the abilities of the person who we are working with.

Once we have identified the behaviors required for a behavior chain, we must identify the Sd associated with each one.

On the toothbrush example:

– Sd1 (wet toothbrush with no toothpaste) – R1 (put toothpaste on a wet brush)

– Sd2 (wet toothbrush with toothpaste) – R2 (brush your teeth)

– Sd3 (feel clean teeth and taste toothpaste) – R3 (rinse mouth with fresh water)

– Sd4 (clean mouth, note messy sink, have toothbrush in hand) – R4 (put toothbrush away)

– Sd5 (put toothbrush away, again note messy sink) – R5 (rinse sink)

Now, let’s recall the Sds and Reponses for this behavior chain.

Chaining Methods

Chaining is a teaching format designed to teach behavior chains. Before you teach using chaining, you would always do a task analysis first, then take the baseline to see which steps of the chain the person can already do and which steps they have trouble with. Then, you pick the type of chaining procedure you are going to use.

There are three types of chaining procedures:

1. Total task presentation

2. Forward chaining

3. Backward chaining

Let’s use the example of making peanut butter sandwich and consider what this would look like for each chaining method.

The behavior chain is:

1. Sd1 (bread in the bag) – R1 (remove two pieces of bread from the bag)

2. Sd2 (have two pieces of bread) – R2 (put peanut butter on top of each piece)

3. Sd3 (have two pieces of bread and peanut butter together) – R3 (put bread together, peanut butter side in)

4. Sd4 (have pieces of bread and peanut butter together) – R4 (cut the sandwich in half)

The reinforcer is having a peanut butter sandwich to eat.

#Total task presentation

In total task presentation, the person is taken through the entire behavior chain. Prompting is provided for any step the person is unable to perform independently.

Of course, the reinforcer is delivered at the end of the task whether or not they have done the steps independently. Over subsequent trials, the prompting is gradually faded out.

For example, in the peanut butter example, you would present the initial Sd

Sd1 – the bag of bread. Then you will prompt the learner (using physical prompts ie.) through all of the steps of making the peanut butter sandwich.

At the end of the chain, the learner gets to eat the sandwich, the natural reinforcer at the end of the chain.

With the total task chaining over several trials, you would gradually fade the prompts until the person can complete the steps by themselves. In the previous example, you might fade from a physical prompt to a partial physical or a gestural prompt.

You may fade your prompts for some steps more quickly than for others, depending on how quickly the person starts to do each step independently. Once the person can complete the entire chain from start to finish without prompting, the chain is mastered.

It is best to use total task presentation when the chain you are teaching is relatively short and not too complex, since the person is required to focus on all steps of the chain.

In contrast, forward and background chaining only require the student learn one step at a time. A person with limited abilities may do better with forward or backward chaining.

#Forward chaining

is the process by which the first step in the chain is taught first. The therapist then finishes off the rest of the chain for the person.

Once the person has learned the first step, then the second step is added. This means the learner must do both the first and second step in sequence before reinforcement is delivered.

Then, once mastered, the third step is added and so on until the entire sequence is mastered.

In any given trial, the therapist completes steps beyond the current step being trained.

Let’s look at an example of forward chaining…

Teaching our peanut butter example using forward chaining, the instructor would:

• Present the first Sd (the bag of bread), prompt the first response if necessary, and provide a reinforcer when the person did it (praise? Token? Not the final product of the sandwich yet)

• Then complete the rest of the chain

• After Sd1 met criteria, start to teach Sd2

• Teaching Sd2 would look like:

o Sd1 (have bread in the bag) – R 1 (remove two pieces of bread from the bag)

o Sd2 (have two pieces of bread) + prompt – R2 (put peanut butter on top of each piece); Provide reinforcer (praise)

o Fade sequence of prompting and prompt for the second step until the client can complete the first two steps independently, then teach the third step and so on.

Like you can see in the example, the therapist will reinforce completion of whatever step the individual is learning. However, the teacher must use artificial reinforcers (ie., praise), as the person cannot experience the natural reinforcer until they are learning the last step of the chain. If the person is learning to remove the bread from the bag, you cannot reinforce this with a bit of the sandwich, as the sandwich isn’t made yet. Let’s compare this with backward chaining.

#backward chaining

involves teaching the last step of the chain first. Once the last step is mastered, the second last step is taught, and so on. using backward chaining, the therapist would already have made the sandwich with the exception of the final step – cutting the sandwich. Let’s look at an example of backward chaining.

The therapist would then present the last Sd and prompt the last step as necessary:

– Sd4 (pieces of bread and peanut butter together) + prompt – R4 (cut sandwich in half) = reinfocer (peanut butter sandwich ready to eat)

Notice what is used as the reinforcer for completing the last step – eating the sandwich the natural reinforcer for completing the chain. As with the other chaining methods, the prompt is faded out over several trials until the person can complete the last step independently. Then, on the next trial, the second last Sd is presented.

• Sd3 (have two pieces of bread with peanut butter) – r3 (put bread together, peanut butter side in)

• Sd4 (have pieces of bread and peanut butter together) – r4 (cut the sandwich in half) = reinfocer (peanut butter sandwich to eat)

Once the learner can do the last two steps, the third last step is taught and so on. in backward chaining, the person is always completing the last step which leads to the natural reinforcer at the end of the chain.

Summary

• Shaping as a procedure for teaching skills – this involves differential reinforcement of successive approximations of a behavior

• Several methods of prompting desired behaviors including

o Response prompts

o Stimulus prompts

• Several ways to fade prompts, including

o Most to least

o Least to most

o Time delay

o Stimulus fading

• Why we fade our prompts- to prevent prompt dependency

• The chain of behaviors and how they can be broken down into a series of Sds and responses that end in reinforcement

• How to write a task analysis

• The three different ways to teach behavior chains

o Total task presentation

o Forward chaining

o Backward chaining

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