Introduction to Applied Behavior Analysis (ABA) Online Tutorial

Module 6: Reducing Problem Behaviors

How Do We Determine the Function of a Behavior?

Determining the function of a behavior is a process that can involve multiple components.

The process might start by talking to someone who knows the child's behavior well. This could be a parent or teacher. To do this, you can use a form such as the Functional Assessment Screening Tool (FAST), which is a questionnaire that gives some preliminary information about what the function of the problem behavior might be. This is considered an indirect method, because you don't directly observe the behavior in question (at this point in the process).

Another component to include is directly observing the problem behavior using an ABC chart, such as the one below. With an ABC chart, we observe the child for a period of time when the behavior is likely to happen. Each time the problem behavior occurs, we write down what happened right before the behavior (the antecedent) and what happened right after the behavior (the consequence).

ABC Chart Example

In this chart, the target behavior is “nose picking” and we note the antecedent (what happened right before the behavior) the consequence (what happened right after the behavior) and what the possible function might be. Once we’ve taken this type of data over time, we look for a pattern to see what a likely function is. For example, if the child’s mom gives him attention (even if it’s negative attention of scolding him) each time he picks his nose, the child may be engaging in the behavior to get her attention. However, if we note that most of the time his mom doesn’t say or do anything when he picks his nose, it may have a sensory function.

It’s also worth noting if the antecedent is the same each time, such as problem behavior only occurring when it’s time to start getting ready to go grocery shopping. There may be an issue with this particular antecedent event (for example, the child might have a sensory issue with the bright lights and crowds at that store). This might lead the child to have problem behavior to serve an avoidance function (to avoid being taken to the store).

Here is an example of filling in an ABC chart for a behavior with a sensory function.

Video From Behavior Frontiers

ABC Charts and FBA forms can be found at the following links:



Another helpful behavior chart and easy to use strategies can be found in this AMAZING book:

Overcoming Autism: Finding the Answers, Strategies, and Hope That Can Transform a Child's Life

Next --> Replacement Behaviors

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