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What is the A-B-A Design in Applied Behavior Analysis?

Psychology has been criticized for many years as an inexact science, not relying on empirical data, and the introduction of the ABA and the ABAB models of research have done much to dispel that idea. The models are especially useful in applied behavioral analysis as they help therapists identify and concentrate on interventions that are successful and avoid wasting time with those that do little to alter behavior.

Related resource: Top 20 Online Applied Behavior Analysis Bachelor’s Degree and BCaBA Coursework Programs


This model is a form of a research protocol called Single Subject Experimental Design. ABA and ABAB are not acronyms as such but refer to the stages of the model. “A” represents the initial unaltered behavior, and that becomes a baseline for the study. The letter “B” is the introduced intervention. So, in the ABA model, the initial behavior is altered by the intervention and then the intervention is withdrawn to see if the behavior returns to the baseline level. The ABAB form of the method is the reintroduction of the intervention after the return to the baseline to judge the strength of the intervention. Some interventions may increase over time while others grow weaker as the person being studied becomes accustomed to the intervention.

How the ABA Model is Used

The model is used in research, but also by therapists to discover treatments for patients with behaviors that affect their life activities. It is especially helpful in the treatment of autistic children because it isolates one behavior to address. An example cited in one article is that of children asked to read a paragraph that included text only. The children were tested on their understanding of the information. Then, another paragraph including an illustration was given to the children to read. Again, they were tested to see if their level of understanding increased. Finally, they were given another paragraph that contained only text and retested to see if their grasp of the information returned to the initial test results. According to an article in the US National Library of Medicine, the primary requirement to judge the effectiveness of this model is the ability of the researcher to replicate the results. A study of the same behavior in several different people should elicit the same results. That replication becomes the basis for identifying the intervention as a universal method of treatment.


The ABA model allows researchers to isolate one behavior for study and intervention. That decreases the chances of other variables influencing the results. It is also a simple way to assess an intervention. As opposed to Randomized Control Trials which depend upon a lot of data from multiple sources, it allows therapists and researchers to study a small group or one individual. The model allows therapists to identify successful interventions quickly. The advantage of the ABAB model is that it ends “on a positive note” with the intervention in place instead of with its withdrawal.


One of the major drawbacks to this model is contained in the question, “what if the behavior does not change with the intervention?” In the Randomized Control Trials, that outcome would be supported by similar findings among many people, but the lack of results invalidates a study of one individual. For instance, the researcher would not know if other variables had been introduced. The other major disadvantage is the ethical problem of identifying a successful intervention and then withdrawing it.

Behavioral analysis is a therapy used with people of different ages and cognitive abilities. Often, therapists work with a patient for a long time to find an intervention that succeeds in modifying a troublesome behavior. The use of the ABA and the ABAB models can shorten the time of treatment and increase the chances of a good outcome for clients of mental health practitioners.