Functional Behavior Assessment Example

May 19, 2025

A functional behavior assessment (FBA) is one of the most important tools in ABA therapy. It is the process of determining why a behavior occurs so that effective interventions can be designed. Understanding what an FBA looks like in practice can help families know what to expect and why this step matters.

What Is a Functional Behavior Assessment?

An FBA is a systematic process for identifying the function, or purpose, of a challenging behavior. Every behavior serves a function for the person engaging in it. The four main functions of behavior are:

Attention: The behavior results in social attention from others (peers, parents, teachers)
Escape/Avoidance: The behavior allows the person to avoid or escape a demand, situation, or activity
Access to tangibles: The behavior results in obtaining a preferred item or activity
Sensory/Automatic: The behavior produces a sensory experience that is internally reinforcing

FBA Example: A Child Who Hits During Transitions

Here is a simplified example of how an FBA might look for a 6-year-old named Marcus who hits when asked to transition between activities:

Step 1: Indirect Assessment

The BCBA interviews Marcus’s parents and teachers, asking questions like:

When does the hitting usually occur? (During transitions, especially from preferred to non-preferred activities)
What happens right before? (An adult tells Marcus to stop what he is doing and move to something else)
What happens right after? (Adults typically back off temporarily or give him more time)
How often does it happen? (3-5 times per day)
Does it happen with all adults or specific ones? (More common with less familiar adults)

Step 2: Direct Observation

The BCBA observes Marcus in multiple settings, collecting ABC data (Antecedent-Behavior-Consequence):

Antecedent: Teacher says “Marcus, time to clean up and go to reading group”
Behavior: Marcus hits the teacher’s arm
Consequence: Teacher steps back, gives Marcus 2 more minutes with current activity

After collecting data across multiple incidents, a pattern emerges: hitting almost always occurs when a demand is placed, and it almost always results in a delay or removal of the demand.

Step 3: Hypothesis

Based on the data, the BCBA hypothesizes that Marcus’s hitting functions as escape/avoidance. He hits to delay or avoid transitions away from preferred activities.

Step 4: Intervention Plan

The BCBA designs an intervention based on the function:

Teach Marcus to request “more time” or “break” verbally or with a visual card (functional communication training)
Use visual timers to make transitions predictable
Provide brief warnings before transitions (5 minutes, 2 minutes, 1 minute)
Reinforce smooth transitions with praise and access to preferred items
Do not allow hitting to result in escaping the transition

Why the FBA Matters

Without an FBA, interventions are based on guesswork. If Marcus’s team assumed his hitting was attention-seeking and responded by ignoring it, the hitting would likely escalate because the actual function (escape) would not be addressed. The FBA ensures the intervention matches the reason for the behavior.

What Families Should Expect

When your child begins ABA therapy, the BCBA will typically conduct an FBA as part of the initial assessment. This process usually involves:

Parent and caregiver interviews (30-60 minutes)
Direct observation across settings (several hours over multiple sessions)
Data analysis and hypothesis development
Presentation of findings and proposed intervention plan
Ongoing data collection to verify the hypothesis and adjust the plan

Getting Started

If your child engages in challenging behaviors and you want to understand why, a functional behavior assessment is the place to start. At Treetop, our experienced BCBAs conduct thorough assessments that lead to effective, individualized intervention plans.