What is a prompt hierarchy in ABA?
A prompt hierarchy is an ordered set of levels of assistance - from full physical guidance through models and gestures down to independence - used consistently by a team so support can be faded as a learner acquires a skill.
A prompt is the help given to make a correct response possible: physical guidance, a model, a gesture, a verbal cue, a positional hint. Ranking them from most to least intrusive gives the team a shared vocabulary for how much help was actually given.
Teams generally work in one of two directions. Most-to-least prompting starts with enough support to guarantee success and fades it; least-to-most starts with the smallest prompt and escalates only as needed. Which one fits depends on the skill and the learner.
The goal is always independence, so the prompt level is recorded on every trial. Watching that level fade over time - not just the percentage correct - is how a BCBA knows a skill is genuinely being acquired rather than propped up.