Specific Experimental Designs(ABAB Design)-Research

• In the ABAB design, baseline (A) and treatment (B) stages are alternated to
determine the effect of treatment on behavior.
• Researchers conclude that treatment causes behavior change when behavior
changes systematically with the introduction and withdrawal of treatment.
• Interpreting the causal effect of the treatment is difficult in the ABAB
design if behavior does not reverse to baseline levels when treatment is withdrawn.
Ethical considerations may prevent psychologists from using the ABAB
design.
• In multiple-baseline designs, a treatment effect is shown when behaviors
in more than one baseline change only following the introduction of a treatment.
• Multiple baselines may be observed across individuals, behaviors, or
situations.
• Interpreting the causal effect of treatment is difficult in multiple-baseline
designs when changes are seen in a baseline before an experimental intervention; this can occur when treatment effects generalize.

The ABAB Design
Researchers use the ABAB design to demonstrate that behavior changes systematically when they alternate “no-treatment” and “treatment” conditions. An initial baseline stage (A) is followed by a treatment stage (B), next by a return to baseline (A), and then by another treatment stage (B). Because treatment is removed during the second A stage, and any improve- ment in behavior is likely to be reversed at this point, this design is also called a reversal design. The researcher using the ABAB design observes whether be- havior changes immediately upon introduction of a treatment variable (first B), whether behavior reverses when treatment is withdrawn (second A), and whether behavior improves again when treatment is reintroduced (second B). If behavior changes following the introduction and withdrawal of treatment, the researcher gains considerable evidence that the treatment caused the behavior change