The Function of Behavior

How a behavior is naturally reinforced for a student

Behavior has meaning. Getty/Banksphotos

Behavior is what we humans do. Behavior is observable and measurable. Whether it is walk from one place to another or to crack our knuckles, behavior serves some "function" or the other.

Applied Behavior Analysis, the research based approach to modifying behavior, seeks to find the "function" of an inappropriate behavior in order to find a replacement behavior to replace it. Every behavior serves some function, and provides a consequence (reinforcement) for the behavior.

When we successfully identify the "function" of the behavior we can reinforce an alternate, acceptable behavior that will replace it. When the student has that particular "need" or function fulfilled by an alternate means, the mal-adaptive or unacceptable behavior is less likely to reappear. If a child needs attention, and we give them attention in an appropriate way because of appropriate behavior, we cement the appropriate behavior and make the inappropriate or unwanted behavior less likely to appear.

The six most common functions for behaviors

  1. To obtain a preferred item or activity.
  2. Escape or avoidance. The behavior helps the child to escape from a setting or activity that he or she doesn't want.
  3. To get attention, either from significant adults or peers.
  4. To communicate. This is especially true with children with disabilities that limit their ability to communicate.
  5. Self Stimulation, when the behavior itself provides reinforcement.
  1. Control or Power. Some of our students feel particularly powerless and a problem behavior may give them a sense of power or control.

Identifying the Function

ABA uses a simple acronym, ABC to define the three pivotal parts of behavior:

Antecedent -- Behavior - Consequence

Antecedent: the environment in which the behavior occurs, the circumstances that surround the occurrence of the behavior or people in the environment when the behavior occurs.

Behavior: The behavior, what the student actually does, needs to be defined


Everything that happens after the behavior, including how people respond to the behavior, what happens to the rest of the students educational program. Ended? Less demand?

Finding the Function

The clearest evidence of how a behavior functions for a child is seen in the Antecedent (A) and the Consequence (C.)

The Antecedent is everything that happens immediately before the behavior occurs. It is sometimes also referred to as "the Setting Event" but a setting event may be part of the antecedent, but not the whole. The teacher/ABA practitioner needs to ask "Is there something in the environment that may lead to the behavior (escaping loud noises, a person who always presents demand, a change in routine that might seem frightening to a child?)" Is there something that happens in that environment that seems to have a causal relationship, like the entrance of a pretty girl, (attention) or a loud noise?

The Consequence In ABA, the term consequence has a very specific meaning, which at the same time is broader than the use of "consequence," as it usually is, to mean "punishment." The consequence is what happens as the result of the behavior.

That consequence is usually the "reward" or "reinforcement" for the behavior. Is the child removed from the room? Does the teacher back off and give the child something easier or fun to do? Does the teacher get really angry and start screaming? It is usually in how the consequence interacts with the antecedent that we can find the function of the behavior.


Example 1: Jeremy has been taking his clothes off in the classroom. During a structured observation, the therapist noticed that when the time for art approaches, Jeremy gets really agitated. When the teacher announces, "Time to clean up to go to art," Jeremy will throw himself on the floor and start pulling his shirt off. It has now gotten to the point where he quickly pulls his socks and pants off, as well, so the office will call his mother to take him home.

Function: Escape. Jeremy doesn't have to go to art class. They need to figure out what it is that Jeremy wants to escape from art. The teacher may start taking his favorite toy to art and not putting any demands on him, or he/she may want to put headsets on Jeremy (the room may be too loud, or the teachers' voice may be too high pitched.

Example 2: The moment that Hilary is given a demand after group, she begins to tantrum. She clears her desk with a sweep, knocks it over and throws herself to the floor. Recently she has added biting. It has taken as much as a half hour to calm her down, but after attacking the other students, the principal has been sending her home with Mom, who she has to herself for the rest of the day.

Function: Once again, escape, though because of the consequence we might say indirectly attention, since she gets the undivided attention of Mom when she gets home. The teacher needs to work on slowly shaping the academic behavior, giving her preferred activities at her desk and make sure there is a home note that helps Mom give Hilary extra attention, away from her typical siblings, when she has a great day.

Example 3: Carlos is seventh grader with low functioning autism. He has been hitting girls when he goes to lunch or gym, not hard (affectionately referred to as "love pats.") He occasionally hits a boy with long hair, but his focus is usually girls. He usually grins after he has done it.

Function: Carlos is an adolescent boy, and he wants the attention of pretty girls (what boy doesn't?) He needs to learn to greet girls appropriately to get their attention.