During an ABAB reversal design, what do the 'A' phases represent?

• A. Phases with intervention
• B. Phases with maintenance
• C. Phases with generalization
• D. Phases without intervention (baseline)

Answer: (D)

Baseline phases are the periods with no intervention. They establish how the target behavior occurs without treatment, giving a point of comparison for what happens when the intervention is introduced. By comparing behavior across the intervention and non-intervention phases, you can see whether the treatment is producing a change and, in a reversal design, whether removing and then reapplying the treatment causes the behavior to move back toward or away from those baseline levels. Maintenance and generalization describe outcomes after treatment, not the phases themselves, and the phases where the treatment is in place are the intervention periods.