A successive approximation in ABA is an observable response that is closer to a defined terminal response along a named dimension and meets the current reinforcement criterion. It is specific to the person, goal, starting repertoire, and context. A vague label such as better effort is insufficient. Families should be able to see the response definition, measurement unit, current threshold, next threshold, reinforcement rule, and criterion-change record.
Define the response dimension first
Choose a measurable feature that matters to the goal: seconds engaged, centimeters from a mark, steps completed, force applied, words or symbols combined, or accuracy within a tolerance. Keep other dimensions visible when they affect safety or quality. A longer response is not necessarily a closer response.
Distinguish approximations from prompts
An approximation describes the learner's response relative to the current criterion. A prompt is added help before or during that response. Record independent and prompted approximations separately so a criterion change does not confuse response improvement with more assistance.
Read the evidence narrowly
A gradual-change review distinguishes shaping changes in response requirements from changes to stimuli, task steps, or reinforcement schedules. A three-participant vocal comparison reported faster mastery under its shaping procedure than a broad reasonable-attempt procedure. That small, older study cannot establish a universal step size or response form.
Include access and choice
The Ethics Code addresses individualized assessment, client involvement, risk, and evaluation. The ASHA guidance supports continued AAC access. A recognizable communication response keeps its meaning even when a separate navigation or complexity skill is being shaped.
A practical example
Leo wants to place a game cursor on a small target. Baseline attempts end within 12 centimeters. The current criterion is within 10 centimeters, followed by 7, 5, and 3 only if data and Leo's report support each move. Device lag is recorded as an invalid opportunity.
Questions families can use
Which dimension defines closer? What range qualifies now? Does a prompt change the score? Which events are invalid? What data move the criterion? Does the terminal response still matter to the person?
Sources
- Association for Behavior Analysis International, Basic Principles in Behavior Analysis
- Behavior Analyst Certification Board, BCBA Test Content Outline, 6th edition
- Vollmer, Gradual Change Procedures in Behavior Analysis
- Shane and colleagues, Shaping Versus Reinforcing Verbal Attempts of Preschoolers with Autism
- Behavior Analyst Certification Board, Ethics Code for Behavior Analysts
- American Speech-Language-Hearing Association, Augmentative and Alternative Communication
Finni resources
