Reversal (ABAB) Design
Structure: Baseline (A), treatment (B), return to baseline (A), reintroduce treatment (B). Demonstrates control by: Showing that behavior changes when treatment is introduced and returns to baseline when treatment is withdrawn. Strengths: Strong demonstration of a functional relationship. Limitations: Cannot be used when the behavior is irreversible (e.g., learned skills) or when it is unethical to withdraw treatment. Requires: At least one reversal (ABA is a minimum; ABAB is preferred).
Multiple Baseline Design
Structure: Baselines are established across multiple participants, settings, or behaviors. Treatment is introduced sequentially (staggered) across tiers. Demonstrates control by: Showing that behavior changes only when treatment is introduced in each tier. Strengths: Does not require withdrawal of treatment. Very versatile. Limitations: Requires independence across baselines. If introducing treatment in one tier affects another, the design is compromised. Minimum tiers: Three (for three demonstrations of effect).
Changing Criterion Design
Structure: After baseline, the criterion for reinforcement is systematically changed in a stepwise fashion. Demonstrates control by: Showing that behavior changes to match each new criterion. Strengths: Ideal for shaping or gradually increasing/decreasing behavior. Does not require withdrawal. Limitations: Only works when behavior can be changed incrementally. Tip: Vary step sizes or include a reversal to strengthen the demonstration of control.
Multielement (Alternating Treatments) Design
Structure: Two or more conditions are rapidly alternated, often within or across sessions. Demonstrates control by: Showing differentiated responding across conditions. Strengths: Efficient; compares conditions quickly. No withdrawal needed. Limitations: Potential for carryover effects between conditions. Requires clear discrimination between conditions. Common use: Comparing the effectiveness of two or more interventions, or in functional analysis to compare conditions.