What Is Chaining?
A behavior chain is a sequence of responses in which each response produces a stimulus that serves as both a conditioned reinforcer for the previous response and a discriminative stimulus for the next. Chaining is the teaching procedure used to establish such sequences. Examples include washing hands, making a sandwich, putting on a jacket, and brushing teeth.
Step 1: Conduct a Task Analysis
A task analysis breaks a complex skill into smaller, teachable components. A good task analysis is observable, in the correct order, and appropriate to the learner's skill level.
Ways to Develop a Task Analysis
- Observe a competent person performing the skill and record each step.
- Perform the skill yourself and note the steps.
- Consult an expert or a published resource.
- Adjust the granularity: use smaller steps for learners who need more support.
Example: Hand Washing
- Turn on water.
- Wet hands.
- Pump soap.
- Rub hands together for 20 seconds.
- Rinse hands.
- Turn off water.
- Dry hands with towel.
Step 2: Assess Baseline Performance
Before teaching, conduct a baseline assessment to see which steps the learner can already complete independently. Two common methods are:
- Single opportunity method: Ask the learner to complete the whole task and score each step until the first error. Provide the remaining steps for the learner or stop.
- Multiple opportunity method: After each error, perform the step for the learner and allow the learner to try the next step. This gives data on each step independent of earlier errors.
Forward Chaining
In forward chaining, the first step is taught first. The learner is prompted through the remaining steps, and reinforcement is delivered after the learner completes the first step independently. When the first step is mastered, the learner is required to complete steps one and two independently, and so on.
Advantages
- Intuitive and follows the natural order of the task.
- Useful when early steps are the most difficult or when later steps depend heavily on earlier ones.
- Allows the learner to practice the beginning of a routine and gain independence in initiating.
Disadvantages
- The reinforcer is delayed because the natural outcome of the task occurs at the end.
- An artificial reinforcer may be needed until the learner reaches the final step.
Backward Chaining
In backward chaining, the instructor completes all steps except the last, which the learner completes independently. After mastery, the learner performs the last two steps, then the last three, and so on until the learner completes the whole chain.
Advantages
- The learner contacts the natural reinforcer (clean hands, finished sandwich, zipped coat) on every trial from the start.
- This can create strong motivation and a sense of accomplishment.
- The last step is often the simplest and builds early success.
Disadvantages
- The learner may be passive during early training because the instructor performs most steps.
- Some learners may not attend to the steps being completed by the instructor.
A variation, backward chaining with leaps, allows the learner to complete the final step and then skip ahead to a larger section of the chain when the learner already has competence in some steps.
Total Task Presentation
In total task presentation, the learner is prompted through every step in every trial, and prompts are faded across steps as the learner becomes more independent. All steps are taught at once. This method is appropriate when the learner already has some of the steps in their repertoire and when the chain is relatively short.
Advantages
- The learner practices the entire chain on every trial.
- Often more efficient for learners with moderate skills.
Disadvantages
- It can be demanding for learners with significant skill deficits.
- Requires careful prompt fading across multiple steps.
Choosing the Right Procedure
- Learner has few steps in repertoire: Use forward or backward chaining.
- Learner is motivated by completion: Use backward chaining so the natural reinforcer follows every trial.
- Learner can complete several steps already: Use total task presentation.
- Learner struggles with early steps but can complete later steps: Backward chaining may allow them to build success first.
- Chain contains steps with problem behavior: Consider where the aversive step falls and use a procedure that makes it easier or provides high reinforcement.
Prompting and Fading in Chains
Use the least intrusive prompt that will lead to correct responding, and fade it as the learner gains independence. Common options include most-to-least prompting, graduated guidance, and time delay. Record the level of prompting needed per step so you can identify steps that require more intervention. Reinforce independent responses at a higher level than prompted responses.
Data Collection
Use a task analysis data sheet with a row per step. Score each step as independent, prompted, or incorrect. Calculate the percentage of steps completed independently and graph the data. Review step-level data to identify specific steps that need further breakdown or a different prompt.
Troubleshooting
- Learner stops progressing: Break the problem step into smaller components or change the prompt type.
- Prompt dependence: Reduce prompt intrusiveness faster or use time delay.
- Learner skips steps: Add visual supports, such as a picture schedule, and reinforce step completion.
- Low motivation: Revisit reinforcers and make sure the outcome of the chain is valuable.
How This Appears on the BCBA Exam
Common questions ask you to identify the procedure from a description: "The therapist completes all steps except the last, which the learner completes independently" describes backward chaining. You may also be asked to choose the best procedure for a learner given certain characteristics, or to explain why backward chaining delivers natural reinforcement. Be clear on the difference between chaining (teaching a sequence) and shaping (reinforcing successive approximations of a single response).
Key Takeaways
- Begin with a task analysis and baseline data.
- Forward chaining teaches from the first step; backward chaining from the last.
- Total task presentation teaches all steps at once with prompt fading.
- Choose the procedure based on the learner's repertoire and motivation.