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ABC's of Behavior

According to Baer, Wolf, and Risley (1968) ...and wikipedia, ABA is the process of systematically applying interventions based upon the principles of learning theory to improve socially significant behaviors to a meaningful degree, and to demonstrate that the interventions employed are responsible for the improvement of behavior. But how do we do this?

Why are you doing that?

Why do people engage in certain behaviors? Well, ABA is based on determinism; the philosophy that every behavior and action is determined by external or environmental causes. On a larger scale, it states that everything that you do from the food you choose to what you say and how you think are determined by your past experiences with your environment and implies that there is no free will. I’m sure not all ABA therapists believe in determinism to that extent, but the field is based upon this philosophy and it certainly works on a small scale of individual behaviors. ABC (antecedent, behavior, consequence) is a way to describe this idea.

An antecedent is something that comes before the behavior and has a probabilistic effect on the behavior to follow. The behavior is what the organism (in our case, the human) does. A consequence is something that occurs after the behavior and as a result of the behavior. This is called a 3 term contingency, meaning all three parts are dependent upon each other. If you change one term, the others may change as well. This is technically called a stimulus-response-stimulus contingency (SRS), but we’ll stick with ABC for simplicity.

Let's look at some examples...

Changing the Behavior


The most commonly changed is the consequence. Let’s look at the example of Avery. Avery wanted a cookie, mom said no, so Avery cried...and cried...and cried. Finally, mom couldn’t take it anymore so she gave her a cookie. Why did Avery cry? Well, in the past when she’s cried, chances are mom gave her what she wanted. Maybe mom tried to hold out and not provide the desired item when she cries, but often it gets to her after a while and she gives in. Unfortunately, that just teaches Avery that instead of crying for 2 minutes to get what she wants, now she knows she has to cry for 10 minutes to get what she wants.

If you stop giving her cookies when she is crying, you will break the crying = cookie equation and over time it will decrease or stop the ‘crying for cookies’ behavior.


Another method for changing behaviors is by manipulating the antecedent. Looking at the same example as above, you could decrease Avery’s motivation for a cookie by giving her free access to cookies throughout the day or giving her a cookie every hour. This method is helpful for behaviors that could be harmful to the child or people around them (which could be increased with extinction) and is often used along with consequence intervention and reinforcing other appropriate behaviors.

This could be used in the example with Sean as well. Sean doesn’t want to do homework anymore and tries to escape from the situation by hitting his mom and running. By giving him a break every few minutes, hitting his mom and running away becomes less important and the behavior decreases.

Final Note

This is just a basic overview of why behaviors occur and how we change it, but it actually takes so much more than the understanding the ABC contingency. This is just one of the steps along the way to obtaining more appropriate behavior. If you have specific questions, contact me or a BCBA in your area.

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