ABCs of Behavior

Parents, schools, and therapists alike frequently contact their BCBAs for questions about problem behavior. The desire to understand the student’s behavior and what can be done to intervene brings us to a cornerstone of Applied Behavior Analysis. Whether there is a new behavior or an existing behavior that has changed, we need to determine WHY the child is engaging in the behavior. It is the BCBA’s job to collect data in order to identify the function of the behavior. They use this information to create behavior intervention plans that are specific to the function of the behavior.


Looking at the behavior itself is not enough to determine the function. We must also look at what happens immediately before and after the behavior. The ABC’s of a behavior are the Antecedent, Behavior, and Consequence. In Cooper, Heron, Heward’s Applied Behavior Analysis, the terms are defined as:


Antecedent: An environmental condition or stimulus change existing or occurring prior to a behavior of interest.

Behavior: The activity of living organisms; human behavior includes everything that people do.

Consequence: A stimulus change that follows a behavior of interest. Some consequences, especially those that are immediate and relevant to current motivational states, have significant influence on future behavior; others have little effect.


So to put it simply, the antecedent is what happens immediately before the behavior occurs, the behavior is what the learner does, and the consequence is what happens immediately after the behavior occurs.


Let’s take a look at an example:


Billy is a 4-year-old boy with autism. He is usually a very good eater, but recently started having tantrums during mealtime. He may throw his plate on the floor, smash the food so that it becomes inedible, or cry and kick at the table.


The therapist begins to take ABC data on Billy’s tantrum behavior during mealtime. Below is a sample of the data sheet.

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But what does this data mean? Every time, the tantrum behavior occurred immediately after mom put peas on Billy’s plate. On 80% of the sessions, Mom removed the meal. On 20% of sessions, Mom followed through on her demand to eat dinner. Based on the small sample of data collected, it is likely that Billy’s tantrum behavior is motivated by escape. The behavior is being maintained by the fact that if he engages in tantrum behavior, Mom might end the meal.


Based on the data we collected, the BCBA would create a plan for the therapist and family to address this problem behavior. The plan could include a goal make sure the whole team follows through on their demands, and that Billy uses his language functionally to say “all done” or “I don’t want peas”.  All along, data will be collected in order to see if the occurrence of the behavior is decreasing with the intervention the BCBA created.


The ABCs don’t just apply to young children with autism either. Here are some real world examples:


A: You have an assignment due Friday.

B: The assignment gets completed and turned in on time.

C: You receive praise for meeting deadlines.

Future Behavior: You turn assignments in on time more often in the future.

Function: You complete work on-time for attention (praise) from your boss.


A: You receive a coupon to your favorite store in an email.

B: You use the coupon to buy something in the store.

C: You save money.

Future Behavior: You use coupons you receive via email more frequently.

Function: You use coupons to avoid spending more money.

Understanding the ABCs of behavior is one of the first steps in knowing how to address a concern. You should not begin an intervention without consulting with a BCBA first. However, now that you have an understanding of antecedents and consequences, you can give the BCBA valuable information that they can use to create an appropriate treatment for the behavior you wish to target.


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