Prompt Hierarchy in ABA: Most-to-Least vs Least-to-Most Prompting
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What is a prompt hierarchy in ABA?
A prompt hierarchy is an ordered list of prompts, from the most intrusive (full physical guidance) to the least (a brief verbal or gestural cue), used to help a learner respond correctly and then fade help. Most-to-least prompting starts with the most help and fades it; least-to-most starts with an independent opportunity and adds help only as needed.
Prompts are extra cues a teacher adds so that the learner gives the correct response while the natural cue (the discriminative stimulus) is present. Prompting only does its job if it is faded: the goal is for the natural cue, not the prompt, to control the response. Cooper, Heron and Heward describe prompting and prompt fading as the core of transferring stimulus control, and the BACB RBT Test Content Outline (3rd ed.), which sets the RBT exam content from 2026, lists "Implement procedures using stimulus and response prompts that include appropriate fading procedures (e.g., errorless, least-to-most, stimulus fading, time delay)" as task C.7.
A prompt hierarchy gives a team one shared order of prompts and one shared set of codes, so every technician delivers and records help the same way. The supervising BCBA chooses the hierarchy and the fading rule in the skill acquisition plan; the technician follows it and records the prompt level on every trial.
Prompt types, from most to least intrusive
| Prompt | Code | What it looks like |
|---|---|---|
| Full physical | FP | Hand-over-hand guidance through the whole response. |
| Partial physical | PP | A light touch at the wrist, elbow or shoulder to start or steer the response. |
| Model | M | The teacher shows the response, then the learner imitates it. |
| Gestural | G | Pointing, nodding or looking toward the correct item. |
| Verbal | V | A spoken hint, partial word or full instruction beyond the original direction. |
| Visual or positional | Vis / Pos | A picture cue, or placing the correct item closer to the learner. These are stimulus prompts. |
| Independent | I | Correct response to the natural cue with no prompt. |
What are the types of prompts in ABA?
Prompts fall into two groups. Response prompts act on the learner’s behavior: physical guidance, modeling, gestures and verbal prompts. Stimulus prompts change the materials themselves, such as moving the correct card closer (positional), adding a color or picture cue (within-stimulus or extra-stimulus) or highlighting part of a word.
The order in the table is a common one, but sources do not all agree. Some hierarchies rank verbal prompts as more intrusive than gestural prompts because spoken prompts are hard to fade and learners can come to wait for them. Use the order written in the learner’s plan, and record the code the plan defines.
Most-to-least vs least-to-most prompting
Most-to-least (MTL): the first trials use the most intrusive prompt that reliably produces a correct response, and help is reduced step by step after a set number of correct prompted trials. MTL keeps errors low, which is why it is often used for new skills and for learners whose errors are hard to correct.
Least-to-most (LTM), also called the system of least prompts: each trial starts with an independent opportunity, and the teacher moves up the hierarchy only after no response or an error within a set wait time. LTM gives the learner a chance to respond alone on every trial but allows more errors.
Libby and colleagues (2008) compared both with children with autism learning play skills. All learners acquired the skill with MTL, which produced fewer errors, but three learned faster with LTM. Adding a short delay before the prompt in MTL (MTL with delay) gave nearly the speed of LTM with fewer errors, and the authors propose best-practice guidelines for choosing a prompting procedure.
| Most-to-least (MTL) | Least-to-most (LTM) | |
|---|---|---|
| First prompt | Most intrusive needed for success | None: independent opportunity first |
| Errors | Fewer | More, especially early |
| Speed | Can slow learning if help is faded too slowly | Faster for some learners |
| Main risk | Prompt dependence if fading stalls | Practicing errors |
| Typical use | New skills, learners with error histories | Skills partly in the repertoire |
How do you fade prompts?
Fading moves control from the prompt to the natural cue. Common methods are moving down the hierarchy after a set criterion (for example, two consecutive correct responses at the current level), graduated guidance (reducing physical pressure within a trial), and time delay. In constant time delay the prompt comes a fixed number of seconds after the instruction once early zero-second trials are done; in progressive time delay the wait grows across trials.
Write the fading rule into the plan so that every technician moves at the same pace. If data show the learner waiting for help, the BCBA may change the hierarchy or the delay. That change is a protocol modification, which is documented by the BCBA (see CPT 97155).
How is the prompt level recorded in session data?
Record the prompt code on every trial, not only whether the trial was correct. Graphs usually show the percentage of trials that were independent, and some teams also graph the percentage at each prompt level so prompt fading is visible over time.
- Use the plan’s codes exactly (FP, PP, M, G, V, I or your own).
- Record errors separately from prompted correct responses.
- Note the hierarchy in use (MTL, LTM, time delay) and any change made by the BCBA that day.
- Report the summary in the session note: trials run, independent trials and the most common prompt level.
How do you write it in an ABA session note?
- Step 1: Name the program and target, and the prompting procedure the plan specifies (MTL, LTM or time delay).
- Step 2: Report trials run, the number and percentage independent, and the count at each prompt level.
- Step 3: Describe errors and how they were corrected, in observable terms.
- Step 4: State whether the learner met the fading criterion and what the next session will do.
- Step 5: Keep the note to what happened; interpretation and plan changes belong to the BCBA.
Example session note (fictional, for illustration only)
Fictional 97153 session, home setting, learner age 6, receptive identification of five animals.
Receptive ID (animals, field of 3), most-to-least prompting with a 3-second delay per plan. 20 trials: 12 independent (60%), 4 gestural, 1 model, 1 partial physical, 2 errors. Both errors, on "horse," were followed by an immediate model prompt and a transfer trial; both transfer trials were independent. Fading criterion (two consecutive sessions at 80% independent) not yet met. Continue at the current delay; data shared with supervising BCBA for review.
Common mistakes
- Recording only "correct" or "incorrect" without the prompt level, so prompt dependence never shows in the data.
- Each technician using a different order of prompts or different codes.
- Repeating the instruction several times, which acts as an unplanned verbal prompt.
- Never fading: running the same prompt level for weeks without a written fading rule.
- Counting a prompted correct response as independent on the graph.
- Writing "needed lots of help" in the note instead of the trial counts at each level.
Frequently Asked Questions
What is the order of the prompt hierarchy?
A common order from most to least intrusive is full physical, partial physical, model, gestural, verbal and then independent. Some sources rank verbal above gestural because verbal prompts are hard to fade. Follow the order written in the learner’s skill acquisition plan.
When should you use most-to-least prompting?
Most-to-least prompting is often chosen for new skills and for learners whose errors are hard to correct, because it keeps errors low. Libby and colleagues (2008) found that adding a short delay before the prompt let learners respond on their own while still keeping errors low.
What is prompt dependence?
Prompt dependence is when a learner waits for a prompt instead of responding to the natural cue. It usually comes from prompts that are not faded or from repeated instructions. Trial-by-trial prompt data make it visible early so the BCBA can adjust the fading plan.
Is a visual schedule a prompt?
Yes. Visual supports such as pictures, written lists and schedules are stimulus prompts. Some are meant to stay in place long term, so the plan should say whether a visual prompt is to be faded or kept as an accommodation.
Does WellNotes record prompt data?
No. WellNotes does not collect trial data. You enter the session details, such as trials run and prompt levels, and the free ABA session note generator drafts the session note for you to review and edit.
Related ABA references and tools
Sources
- Cooper JO, Heron TE, Heward WL. Applied Behavior Analysis (3rd ed.). Pearson (Open Library record)
- Behavior Analyst Certification Board. RBT Test Content Outline (3rd ed.), RBT examination content from 2026
- Libby ME, Weiss JS, Bancroft S, Ahearn WH. A comparison of most-to-least and least-to-most prompting on the acquisition of solitary play skills. Behav Anal Pract 2008;1(1):37-43
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