What is a Functional Behavior Assessment (FBA)?

A Functional Behavior Assessment (FBA) is a systematic process used to understand the underlying reasons or functions behind challenging behaviors exhibited by individuals, particularly those with autism and other developmental disorders. By identifying the cause of a behavior, behavior analysts can develop effective intervention strategies to address and modify the behavior.

FBAs involve a thorough analysis of the behavior in question, examining the context in which it occurs, the antecedents (what happens before the behavior), and the consequences (what happens after the behavior). This approach helps identify patterns and triggers, allowing for a deeper understanding of why the behavior is happening.

Basic History of Functional Behavior Assessment

The concept of Functional Behavior Assessment emerged from the field of Applied Behavior Analysis (ABA), which is rooted in the principles of behaviorism. Behaviorism, a theory established in the early 20th century by psychologists such as John B. Watson and B.F. Skinner, focuses on the idea that behaviors are learned through interactions with the environment and can be modified through reinforcement and punishment.

In the 1960s and 1970s, ABA began to gain recognition as an effective approach for treating individuals with autism and other developmental disorders. Researchers and practitioners realized that to effectively address challenging behaviors, it was crucial to understand the function or purpose that these behaviors served for the individual. This realization led to the development of Functional Behavior Assessment as a tool to systematically identify the functions of behaviors.

The formalization of FBA as a process was influenced by the work of pioneers such as Dr. Ivar Lovaas, who conducted groundbreaking research on the use of ABA to treat autism. His work emphasized the importance of individualized and data-driven approaches to behavior modification. Over time, FBA became a standard practice within ABA, supported by empirical evidence demonstrating its effectiveness in creating targeted and successful behavior intervention plans.

Benefits of Functional Behavior Assessment

The primary benefits of conducting an FBA include:

  • Identifying the Root Cause: Understanding why a behavior occurs is essential for developing effective interventions.
  • Tailored Interventions: Interventions based on FBA results are customized to meet the individual needs of the person.
  • Improved Behavior: Targeted interventions can lead to significant improvements in behavior, enhancing the individual’s quality of life.
  • Preventing Future Issues: By addressing the root cause of a behavior, future occurrences can be minimized or prevented.
  • Empowering Caregivers: Providing caregivers with strategies to manage and modify challenging behaviors effectively.

Who Should Conduct an FBA?

FBAs should be conducted by trained professionals, such as Board-Certified Behavior Analysts (BCBAs) or Licensed Behavior Analysts (LBAs). These professionals have the expertise to observe, analyze, and interpret behavior accurately. They also have the skills to develop and implement effective intervention plans based on FBA findings.

How is an FBA Performed?

Performing an FBA involves several steps:

  1. Define the Behavior: Clearly describe the challenging behavior in observable and measurable terms. For example, instead of saying “aggressive behavior,” specify “hitting others with an open hand.”
  2. Gather Information: Collect data through direct observation, interviews with caregivers, teachers, and other relevant individuals, and review of existing records. Tools such as behavior rating scales and questionnaires can also be used.
  3. Analyze Data: Examine the collected data to identify patterns and possible triggers for the behavior. Look for antecedents (what happens before the behavior) and consequences (what happens after the behavior).
  4. Formulate Hypotheses: Develop hypotheses about the function of the behavior. Common functions include seeking attention, escaping a task or situation, accessing tangible items, or sensory stimulation.
  5. Test Hypotheses: Conduct further observations or experimental manipulations to test the validity of the hypotheses. This step helps confirm the function of the behavior.
  6. Develop Intervention Plan: Based on the confirmed hypotheses, create a behavior intervention plan (BIP) that includes strategies to address the behavior. This may involve teaching alternative behaviors, modifying the environment, and changing the way others respond to the behavior.
  7. Implement and Monitor: Implement the intervention plan and monitor its effectiveness over time. Make adjustments as necessary based on ongoing data collection and analysis.

How Does a Therapist Prepare for an FBA?

Preparation is key to conducting a successful FBA. Therapists should:

  • Understand the Individual: Familiarize themselves with the individual’s history, strengths, and challenges through records and initial interviews.
  • Gather Tools: Prepare data collection tools, such as observation forms, questionnaires, and recording devices.
  • Schedule Observations: Plan observation times that cover different settings and activities to get a comprehensive understanding of the behavior.
  • Collaborate with Others: Communicate with caregivers, teachers, and other relevant individuals to gather diverse perspectives and insights.

Examples of FBA in Practice

Example 1: Identifying Attention-Seeking Behavior

Case Study: Alex, a 7-year-old boy with autism, frequently throws objects during class. His teacher notes that this behavior usually occurs during independent work time.

FBA Process:

  • Define the Behavior: Throwing objects.
  • Gather Information: Interview the teacher, observe Alex in class, and review his school records.
  • Analyze Data: The behavior occurs when Alex is not receiving direct attention from the teacher.
  • Formulate Hypotheses: Alex throws objects to gain the teacher’s attention.
  • Test Hypotheses: Increase attention during independent work to see if the behavior decreases.
  • Develop Intervention Plan: Implement a strategy where the teacher periodically checks in with Alex during independent work and praises him for appropriate behavior.
  • Implement and Monitor: The plan is implemented, and Alex’s object-throwing decreases significantly over time.

Example 2: Addressing Escape-Motivated Behavior

Case Study: Mia, a 10-year-old girl with Down syndrome, frequently leaves her desk during math lessons. Her parents report similar behaviors at home during homework time.

FBA Process:

  • Define the Behavior: Leaving the desk.
  • Gather Information: Interview the parents and teacher, observe Mia during math class and homework time, and review her academic records.
  • Analyze Data: The behavior occurs specifically during math-related activities.
  • Formulate Hypotheses: Mia leaves her desk to escape difficult math tasks.
  • Test Hypotheses: Simplify math tasks and provide support to see if the behavior decreases.
  • Develop Intervention Plan: Break down math tasks into manageable steps, provide frequent breaks, and offer praise for completing each step.
  • Implement and Monitor: The plan is implemented, and Mia remains at her desk for longer periods, completing more tasks.

Effectiveness of FBA

FBAs are highly effective in understanding and addressing challenging behaviors. Research has shown that interventions based on FBA results are more successful in reducing problematic behaviors compared to non-specific interventions. By tailoring strategies to the individual’s specific needs and the function of their behavior, FBAs help create lasting positive changes.


Functional Behavior Assessments are a critical component of Applied Behavior Analysis (ABA) therapy. They provide a structured approach to understanding the reasons behind challenging behaviors and developing effective interventions. By conducting thorough FBAs, behavior analysts can create personalized strategies that lead to meaningful improvements in behavior and overall quality of life for individuals with autism and other developmental disorders.