To teach new skills using behavior chaining, an ABA therapist will prompt the client what to do next. There are several types of prompting that can be used, with each step placed into a prompting hierarchy.
The most common prompting hierarchies are most-to-least and least-to-most prompting. The goal of any type of behavior training with prompting is to support the client in learning the skill so thoroughly that they do not need prompting.
What Is Prompting?
Prompting is a component of behavior chaining, a core approach to skill-building in applied behavior analysis (ABA). Behavior chaining involves taking a specific task apart into its baseline pieces.
A classic example is properly brushing your teeth, which starts with picking up the toothbrush, picking up the toothpaste, taking the cap off the toothpaste, putting some paste onto the brush, and so on. Breaking a skill down into much smaller tasks helps each step in the chain make sense in its proper order.
People on the autism spectrum sometimes do not easily pick up steps in behaviors or skills like brushing their teeth. For example, they may forget to put paste on the toothbrush. Behavior chaining is often part of ABA therapy to help with this.
How Are the Types of Prompting Hierarchies Used?
Many skills, from simple to complex, can be taught with behavior chaining.
To start the process of chaining behaviors together, an ABA therapist will work with their client, often a child on the autism spectrum, using prompting for the next part of the task. Prompts are chained together in a hierarchy, either least-to-most (LTM) or most-to-least (MTL) prompting.
- Least-to-most prompting: Also called fading, the ABA therapist may discuss each step of a new skill with the child beforehand, but the main part of each behavior chaining session starts with the child responding independently to each step. The therapist may provide prompts for the next part, but these will be minimal.
- Prompts may become increasingly intrusive if the child needs more help throughout the process of learning the skill. However, there will still be some delays between prompts, allowing the child to respond and figure out the next step on their own.
- Most-to-least prompting: While LTM starts with less instruction, MTL prompting begins with a lot of interaction between the ABA therapist and the child. For example, the therapist may place their hands on the child’s hands, guiding them through each step of the process so they know what the skill feels like. Then, in later sessions, the therapist will be less intrusive or involved with prompting. For example, they may move their hands like the child should move their hands, but they will not guide the child’s hands for them.
- As the child learns the behavior chain more thoroughly in sessions, the therapist will use less intrusive prompts until the child no longer needs any prompting.
A study conducted in 2008 reported that, in most cases, children on the autism spectrum learn new skills faster with the MTL prompting hierarchy compared to LTM. Adding a time delay between each prompt allowed the children in the study to respond on their own, which seemed to produce even more rapid skills acquisition. However, the study authors noted that children who already had acquired a skill but perhaps needed refinement, or who showed rapid skills acquisition with MTL, benefitted from an LTM prompting hierarchy.
Ultimately, the prompting hierarchy used varies based on the child’s individual needs and existing skills. An ABA therapist may begin early sessions with MTL as part of assessing the child’s needs but can change to different prompting hierarchies for other skills later.
More-to-Less Prompting Hierarchy
With most-to-least prompting, intrusive gestures, words, or other stimuli are used to guide the child through the task and onto the next, to build the entire process for a specific skill. This involves creating a skill checklist to measure the acquisition of the skill through each step and each session.
For example, learning to put on a jacket may involve:
- Taking the jacket out of the closet or off the hook.
- Holding it upright.
- Unzipping it.
- Putting the right arm into the right sleeve.
- Moving the jacket behind the back.
- Putting the left arm into the left sleeve.
- Making sure the hands come out of the cuffs comfortably.
- Zipping up the jacket.
The MTL prompting hierarchy might start with the ABA therapist guiding the child’s hands as they perform each step, so the child understands how it feels to put the jacket on. As the therapist guides each step, they may say the words for the step out loud. Then, in the next session, the therapist may simply say each step out loud, unless the child needs more help to complete it.
Through each session, the therapist will prompt less often until the child knows each step to put their jacket on.
Less-to-More Prompting Hierarchy
When using the LTM prompting hierarchy, ABA therapists begin similarly, identifying the target skill or behavior they wish the child to acquire and outlining the steps necessary to complete the skill. Then, the therapist must identify the target stimulus that will help the child continue to use the behavior outside of the session rather than associating it with the therapist or the therapy session. This becomes part of the behavior chain.
For example, when learning to properly wash one’s hands, the stimulus might be that the child has gotten their hands dirty, or they are about to sit down and eat a meal. Unlike MTL, LTM then involves figuring out which type of prompting to use if the child needs help figuring out the next step. Examples include:
- Material or environmental manipulation, which should create the stimulus that indicates the child must complete the skill, like washing their hands.
- Task direction, by telling the child that it is time to have a snack, holding up a cue card with a picture of hands being washed, and asking the child to identify the behavior.
- Naturally occurring event, such as the child getting their hands dirty during another ABA therapy activity like painting.
Once the child has been prompted to wash their hands, the ABA therapist waits for them to begin the process without further prompting. LTM works well for children who already know some steps in the skill, like washing their hands, but may need additional prompting to learn how to complete it appropriately. For example, the therapist may add in counting out loud to 20, so the child washes their hands with soap for 20 seconds.
Prompting Hierarchies Are a Core Component of Behavioral Chaining
It is important for ABA therapists to avoid missing steps in either prompting hierarchy because it can be difficult to start learning the process again. Therapists should also stick to the plan in regard to which type of prompting hierarchy they use and fade appropriately. Interrupting the type of prompting with a more or less invasive type can change how the child learns the skill, or it might lead them to learn a step incorrectly.
These prompting hierarchies work well in ABA therapy and help many children on the autism spectrum learn a range of skills. This includes not just daily tasks like brushing teeth or getting dressed, but also skills like writing letters, interacting with other children on the playground, or managing a calendar.
A Comparison of Most-to-Least and Least-to-Most Prompting on the Acquisition of Solitary Play Skills. (Spring 2008). Association of Behavior Analysis International (ABAI).
Using the System of Least to Most Prompts. Nevada Dual Sensory Impairment Project. University of Nevada, Reno.
Steps for Implementation: Least-to-Most Prompts. (October 2010). National Professional Development Center on Autism Spectrum Disorders.