Overview
Skill acquisition in ABA refers to the systematic teaching of new behaviors using evidence-based procedures. RBTs implement skill acquisition programs (SAPs) designed by BCBAs, using structured techniques like DTT, prompting hierarchies, chaining, and shaping. Understanding these procedures — and collecting accurate data — is essential for the RBT exam and effective practice.
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Discrete Trial Training (DTT)
What Is DTT?
DTT is a structured teaching method that breaks instruction into clear, repeated trials. Each trial has a defined beginning, middle, and end, making it easy to measure learning.
The Three Components of a Discrete Trial
| Component | Description | Example |
|---|---|---|
| Discriminative Stimulus (SD) | The instruction or cue | "Touch nose" |
| Learner's Response | What the learner does | Touches nose |
| Consequence | Reinforcement or error correction | "Great job!" + sticker |
• Inter-trial interval (ITI): The brief pause (1–5 seconds) between trials; allows the learner to reset before the next SD
Trial Formats
• Mass trials: Same SD repeated consecutively; used to build initial responding for brand-new skills
• Distributed (expanded) trials: Target skills are interspersed among other tasks across the session; promotes maintenance and generalization
Key Terms
• SD (Discriminative Stimulus) – The cue that signals reinforcement is available for a specific response
• Consequence – What follows a response (reinforcement or error correction)
• ITI – Inter-trial interval; the reset pause between trials
⚠️ Watch Out For
• Confusing mass trials (building new skills) with distributed trials (promoting generalization) — know when each is used
• Forgetting that the ITI comes after the consequence, not before the SD
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Prompting Strategies
Prompt Types: Most to Least Intrusive
1. Full physical – Hand-over-hand guidance
2. Partial physical – Light touch or tap to guide
3. Modeling – Demonstrating the correct response
4. Gestural – Pointing or nodding toward the answer
5. Positional – Placing the correct item closer to the learner
6. Verbal – Spoken hint or instruction
Prompting Hierarchies
• Most-to-Least (MTL): Start with maximum support, gradually fade toward independence
- Best for: New learners, errorless approaches
• Least-to-Most (LTM): Start with minimal support, increase help only when errors occur
- Best for: Learners with some existing skills
Prompt Fading & Dependency
• Prompt fading: Systematically reducing prompts over time so the learner responds to the natural SD
• Prompt dependency: When a learner only responds correctly when prompted — caused by failing to fade prompts
• Goal: Transfer stimulus control from the prompt → the natural SD
Time Delay Prompting
• A pause is inserted between the SD and the prompt, encouraging the learner to respond independently
• Constant time delay: Fixed pause (e.g., always 5 seconds)
• Progressive time delay: Pause gradually increases over sessions (e.g., 0 → 2 → 4 → 6 seconds)
Key Terms
• Prompt – Any supplemental stimulus that helps evoke the correct response
• Prompt fading – Gradual removal of prompts over time
• Prompt dependency – Over-reliance on prompts; failure to respond to the natural SD
• Stimulus control – When the SD reliably evokes the target response without prompts
⚠️ Watch Out For
• MTL vs. LTM: MTL = start big, go small. LTM = start small, go big. Don't mix them up!
• A gestural prompt is a movement (pointing), not a verbal cue — keep these categories distinct
• Prompt dependency is caused by the therapist's failure to fade, not the learner's fault
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Chaining
Task Analysis
A task analysis breaks a complex, multi-step skill into a sequence of smaller, individually teachable steps.
• Example: "Washing hands" = turn on water → wet hands → apply soap → scrub → rinse → dry
Three Chaining Methods
| Method | Teaching Order | Who Completes Other Steps? | Best Used When... |
|---|---|---|---|
| Forward chaining | Step 1 first → progress forward | Therapist completes remaining steps | Natural sequence matters; initial steps are motivating |
| Backward chaining | Last step first → progress backward | Therapist completes all prior steps | Learner benefits from completing/finishing the task |
| Total task chaining | All steps every session | Learner attempts all steps | Chain is short OR learner has prerequisite skills |
Key Terms
• Task analysis – Breaking a complex skill into sequential steps
• Chain – The full sequence of steps making up a skill
• Forward chaining – Teach first step first
• Backward chaining – Teach last step first
• Total task chaining – Practice all steps every session
⚠️ Watch Out For
• In backward chaining, the therapist still completes the early steps — the learner works on the last step
• Total task is not always "best" — it requires the learner to have sufficient prerequisite skills
• Task analyses must be completed before chaining begins
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Shaping & Naturalistic Teaching
Shaping
• Shaping = reinforcing successive approximations of the target behavior
• Each step gets closer to the final target; the reinforcement criterion is gradually raised
• Example: Teaching a child to say "water" — first reinforce "wa," then "wawa," then "water"
Naturalistic Teaching Approaches
• Natural Environment Teaching (NET): Embeds teaching trials into naturally occurring activities using the learner's own motivation and natural reinforcers
• Incidental teaching: Capitalizes on learner-initiated interactions; the therapist requires a more elaborate response before granting access to a desired item
Generalization & Maintenance
• Generalization: The skill occurs across different settings, people, materials, and times — the real-world transfer of learning
- Types: Stimulus generalization, response generalization
• Maintenance: The skill continues to occur after active teaching has stopped — the skill is durably learned
Key Terms
• Successive approximations – Behaviors that gradually resemble the target behavior more closely
• Generalization – Performing a skill across varied conditions
• Maintenance – Continued performance of a skill over time after teaching is reduced
⚠️ Watch Out For
• Shaping requires raising the criterion — reinforcing the same approximation forever is NOT shaping
• NET is learner-motivated; incidental teaching is specifically learner-initiated — a key distinction
• Generalization and maintenance are goals, not automatic outcomes — they must be programmed for
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Data Collection & Mastery Criteria
Mastery Criteria
• A mastery criterion is a pre-defined performance standard the learner must meet before a skill is considered mastered
• Example: 80% correct across 3 consecutive sessions
• Must be established before teaching begins (part of the SAP)
Percent Correct Data
• Formula: (Correct Responses ÷ Total Trials) × 100
• Tracks progress toward mastery
• Example: 8 correct out of 10 trials = 80%
Errorless Learning
• Uses immediate, intrusive prompting to prevent errors before they occur
• Primary benefits:
- Minimizes learner frustration
- Prevents reinforcement of incorrect responses
- Builds a history of correct responding
Skill Acquisition Program (SAP)
A SAP is a written document that specifies:
• Target behavior(s)
• Materials
• Prompting strategy
• Reinforcement procedures
• Mastery criterion
• Data collection method
Stimulus Control
• Stimulus control = the SD reliably evokes the correct response
• Skill acquisition aims to establish stimulus control under the natural cue, not the prompt
• No stimulus control = the learner responds randomly or only with prompts
RBT vs. BCBA Roles
| Role | Responsibilities |
|---|---|
| BCBA | Designs the SAP, selects targets, determines prompting strategy and mastery criteria |
| RBT | Implements the SAP as written, collects data, reports to BCBA |
> 🔑 The RBT does not modify the program — any changes must be approved by the supervising BCBA.
Key Terms
• Mastery criterion – The pre-defined standard for skill mastery
• Percent correct – Correct responses ÷ total trials × 100
• SAP – Skill Acquisition Program; the written guide for teaching a skill
• Errorless learning – Prompting immediately to prevent errors
• Stimulus control – SD reliably evokes correct responding
⚠️ Watch Out For
• An RBT never modifies a SAP without BCBA approval — this is a common exam trap
• Errorless learning ≠ no errors ever — it means errors are minimized through prompting
• Mastery criteria must include both a percentage and a consistency requirement (e.g., "3 consecutive sessions")
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Quick Review Checklist
Discrete Trial Training
• [ ] Know the 3 components of a discrete trial: SD → Response → Consequence
• [ ] Know the ITI is a pause between trials (1–5 seconds)
• [ ] Distinguish mass trials (new skills) from distributed trials (generalization/maintenance)
Prompting
• [ ] Memorize prompt types most to least intrusive: Full physical → Partial physical → Modeling → Gestural → Positional → Verbal
• [ ] Distinguish MTL (start intrusive) vs. LTM (start minimal)
• [ ] Know prompt fading prevents prompt dependency
• [ ] Know constant vs. progressive time delay
Chaining
• [ ] Know how to write and use a task analysis
• [ ] Distinguish forward (first step first), backward (last step first), and total task (all steps, all sessions)
Shaping & Naturalistic Teaching
• [ ] Shaping = reinforcing successive approximations
• [ ] Distinguish NET (embedded, learner-motivated) from incidental teaching (learner-initiated)
• [ ] Know generalization and maintenance must be programmed for
Data & Mastery
• [ ] Know the percent correct formula: (correct ÷ total) × 100
• [ ] Know mastery criteria require both a percentage and consistency (e.g., 3 sessions)
• [ ] Understand errorless learning prevents errors through immediate prompting
• [ ] Know the RBT implements; the BCBA designs — RBTs do NOT modify programs