ABA glossary
Least-to-most prompting
Also called increasing assistance
Definition
A prompting procedure that starts each trial with the least intrusive help, often the instruction alone, and adds more intrusive prompts only as needed until the learner responds correctly.
In plain words
Least-to-most (increasing assistance) gives the learner a chance to respond independently first. If the learner does not respond correctly within a set time, the next prompt in the hierarchy is given, for example gesture, then model, then physical guidance. Prompts fade naturally as the learner starts responding at lower levels. Because the learner may make errors before the effective prompt arrives, it fits learners who already have part of the skill.
Example from a session
For putting on a coat, the program uses a least-to-most hierarchy with a 3-second wait at each level. The RBT says, "Put on your coat," and waits. When Mia does nothing, the RBT points to the coat, waits 3 seconds, then models putting an arm in, waits 3 seconds again, and only then gives light physical guidance. The RBT records the level that produced the correct response so the BCBA can see progress.
For BCBA candidates and supervisors
Least-to-most allows errors on early trials, so analysts avoid it when errors cause problem behavior, when they are dangerous, or when the learner is likely to practice mistakes. It requires consistent wait times and a clearly ordered hierarchy, which staff can drift from. Analysts compare data across prompting procedures for the individual learner rather than assuming one is always better, and they monitor whether the learner begins to wait for prompts rather than responding.
Often confused with most-to-least prompting, prompt dependence
Least-to-most starts with no or minimal help and increases help within the trial; most-to-least starts with maximum help and reduces it across trials. Prompt dependence is a possible problem with either, when the learner waits for help instead of responding to the natural cue.
Exam tip
Look for "waited, then gestured, then modeled." That pattern of increasing help within a trial is least-to-most. If errors are a concern in the stem, the better answer usually avoids least-to-most.
Can you spot least-to-most prompting in a scenario?
Practice RBT C.7 with exam-style questions and instant feedback.