Question: How many consecutive phases are required for a reversal design?

Answer: three.

A reversal design requires at least three consecutive phases: Phase 1 – Initial Baseline (A), Phase 2 – Intervention (B), and Return to Baseline – Phase 3; that’s (A). ABA is the minimum number: ABA – Baseline – Intervention – Baseline, is the minimum number. Keep in mind, with each reversal, you strengthen experimental control. So, ABAB is preferred over ABA as a stronger design, and so on. For reversals to occur, the behavior in the return to baseline must approximate the initial baseline levels, basically the same performance levels. And last but not least, the reversal design is the most powerful within-subject design for demonstrating function. Think of it as proof of function.

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Sequence effects

A confounding effect on a subject’s behavior in a given condition that results from the subject’s experience with a previous condition.

Reversal design

Any experimental design in which responding is reversed to a level obtained in a previous condition by alternating between specific independent variables and baseline conditions.

Multiple baseline design

An experimental design in which the effect of one independent variable is measured and evaluated within and across combinations of two or more subjects, behaviors, or settings.

Multiple treatment interference

In an experimental design that requires the implementation of more than one independent variable to one subject, the outcome of one treatment may be influenced by the effect of another.

Multielement design

An experimental design in which two or more independent variables are presented in rapidly alternating succession, and the differential effects of each independent variable on the target behavior are measured.

Irreversibility

A behavior for which the effects of treatment cannot be undone. Therefore, it cannot return to a baseline level of responding when an independent variable is removed.

Changing criterion design

An experimental design in which an initial baseline phase is followed by a series of treatment phases consisting of successive, stepwise, and gradually changing criteria for which reinforcement or punishment…

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