Chaining is a type of intervention that aims to create associations between behaviors in a behavior chain. A behavior chain is a sequence of behaviors that happen in a particular order where the outcome of the previous step in the chain serves as a signal to begin the next step in the chain. In terms of behavior analysis, a behavior chain is begun with a discriminative stimulus (SD) which sets the occasion for a behavior, the outcome of that behavior serves as a reinforcer for completing the previous step and as another SD to complete the next step. This sequence repeats itself until the last step in the chain is completed and a terminal reinforcer (the outcome of a behavior chain, i.e. with brushing your teeth the terminal reinforcer is having clean teeth) is achieved. For example, the chain in brushing your teeth starts with seeing the toothbrush, this sets the occasion to get toothpaste, which then leads to putting it on your brush, brushing the sides and front of mouth, spitting out the toothpaste, rinsing your mouth, and finally putting away your toothbrush. To outline behavior chains, as done in the example, we use a task analysis.
Chaining is used to teach complex behaviors made of behavior chains that the current learner does not have in their repertoire. Various steps of the chain can be in the learner’s repertoire, but the steps the learner doesn’t know how to do have to be in the category of can’t do instead of won’t do (issue with knowing the skill not an issue of compliance). There are three different types of chaining which can be used and they are forward chaining, backward chaining, and total task chaining (not to be confused with a task analysis).
In order to implement a behavior chain procedure, first you must recognize all the steps in the chain you wish to teach. To do so, you conduct a task analysis which can be done in one of three ways. The first way is for you to ask someone who is an expert on the task what all the steps involved are. The second is to watch someone do the chain who is competent enough to complete it and list all the steps you see. The last, and most common way it is done, is to complete the behavior chain yourself and outline the steps that you did. Task analysis can be as detailed as necessary depending on the ability of the learner.
For example, a task analysis of hanging up a shirt for a typically developing 10-year-old may be to first grab a hanger, grab a shirt, put the hanger in the hole for the head, then hang it in the closet. For an atypically developing 10-year-old, it may be get a hanger, grab a shirt, hold the hanger by the hook, put one side of the hanger in the head hole, put the other side of the hanger in the head hole, then hang up the shirt in the closet.
Typically, the task analysis will have three parts outlined for each step, the SD associated, the behavior, and the outcome which serves as the reinforcer for the previous step and SD for the next step. Using the hanging up a shirt example again, the SD for putting the hanger in the head hole is holding a shirt and a hanger, the behavior is putting the hanger in the hole, and the reinforcer/SD for the next step is holding the hanger with the shirt held on it.
As mentioned earlier, there are three different chaining procedures: forward chaining, backward chaining, and total task chaining. Although the research has not concluded which procedure is best, the procedure that you use will be determined by the skillset of the learner as well as the what works best for the learner. The whole point of using chaining is to teach a complex behavior by breaking it into multiple, easier steps that when done in order create the complex behavior. For example, washing hands is a complex behavior that can be broken down into 7 easy steps: turn on water, get hands wet, get soap, scrub hands, rinse hands, turn off water, dry hands.
Forward chaining is a procedure where the learner completes the first step in the chain and then is prompted through the remaining steps in the chain. Once the learner is consistently completing the first step, you have them complete the first and second step then prompt the remaining steps and so on until the learner is able to complete the entire chain independently. Reinforcement is delivered for completion of the step, although they do not attain the terminal reinforcer (outcome of the behavior chain) until they are prompted through the remaining steps.
Backward chaining is just like forward chaining but starting with the last step. The tutor will prompt the learner through all the steps in the chain except the last one. The learner will complete the last step in the behavior chain independently and once they are doing so consistently, you can begin to have them do the second to last step and the last step and so on until they complete all the steps in the chain independently. The biggest benefit of using a backwards chain is that the learner receives the terminal reinforcer (the outcome of the behavior chain) naturally. Backward chaining is the preferred method when teaching skills to individuals with severe delays because they complete the last step and see the direct outcome of the chain immediately rather than having to be prompted through the remaining steps to receive that reinforcement.
Total task chaining is a procedure where you allow the learner to try to independently complete each step in the chain and if they don’t complete the step correctly, then the tutor will prompt the learner through that step then, again, allow them to independently complete the next step. Total task chaining can be used for individuals who know how to complete all the steps in a chain but don’t know how to do them in the correct order. Typically, it is used with individuals who do not have severe impairments and when the chain is not very long.
When an error occurs at any point in the behavior chain, there is a procedure which should typically be followed. Of course, this is a case by case situation, but typically at the point of error, you will want to take one step back and complete the step before the error occurred and then prompt the following step that the error happened at. Ideally, you would then be able to go back to the step before the error occurred and have them do that step and the following step independently. For example, if with washing hands the learner makes an error when rubbing their hands, you will have them get soap again and then prompt them to scrub their hands. After, again depending on the client and person who is in charge of the program, you will want to have them get soap again and see if they independently scrub their hands.
The reason you go one step back instead of just prompting the step that was wrong is because you want to create the associations with that previous step and performing the next step correctly. You want the learner to know that, for example with washing hands and getting the scrubbing step wrong, seeing the soap in their hands means that they need to scrub their hands together. If you just prompt them to scrub their hands without them getting the soap first, then you may run into the issue of them not knowing that they need to scrub with soap. Additionally, you run the risk of adding incorrect steps into your chain if you prompt without completing the previous step. Using the same example, if the learner gets soap then rinses it off and you regularly prompt them to rub their hands together without getting soap, they may add the step of rinsing the soap off their hands before scrubbing to the chain.