What Is a Functional Behavior Assessment?
A functional behavior assessment (FBA) is a systematic process for identifying the variables that maintain a target behavior. Rather than focusing on what a behavior looks like, an FBA answers why the behavior occurs by identifying its antecedents, consequences, and maintaining function. This information is critical for designing effective, individualized intervention plans.
The FBA process is foundational to ethical behavior-analytic practice. The BACB Ethics Code requires that behavior analysts conduct assessments before implementing interventions, and functional assessment is the gold standard for understanding problem behavior.
The Four Functions of Behavior
All behavior serves one or more functions, typically categorized into four broad categories:
- Attention - The behavior produces social interaction, reactions, or engagement from others
- Escape/Avoidance - The behavior results in the removal or delay of an aversive stimulus or demand
- Access to Tangibles - The behavior produces access to preferred items, activities, or events
- Automatic/Sensory - The behavior produces its own reinforcement independent of social mediation
Understanding the function of behavior is essential because two topographically identical behaviors (for example, two children hitting their peers) may serve entirely different functions and therefore require entirely different interventions.
Indirect Assessment Methods
Indirect assessments gather information about the target behavior from people who are familiar with the individual. These methods are typically the first step in the FBA process.
Interviews
Structured interviews with caregivers, teachers, and other relevant parties provide context about when, where, and under what conditions the behavior occurs. The Functional Assessment Interview (FAI) developed by O'Neill and colleagues is a widely used structured interview format.
Rating Scales
Standardized rating scales like the Motivation Assessment Scale (MAS) and the Questions About Behavioral Function (QABF) provide quantitative data about the likely function of behavior based on informant responses. While convenient, these tools should be used as supplements to direct observation rather than as standalone assessments.
Record Reviews
Reviewing existing records, including medical history, previous assessment reports, individualized education programs (IEPs), and behavior incident reports, provides historical context that informs the current assessment.
Direct Observation Methods
Direct observation involves systematically watching and recording the target behavior in the natural environment. These data provide more reliable information than indirect methods alone.
ABC Data Collection
Antecedent-Behavior-Consequence (ABC) data recording is the most common direct observation method. The observer records what happens immediately before the behavior (antecedent), the behavior itself, and what happens immediately after (consequence). Patterns in ABC data reveal potential functional relationships.
Scatterplot Analysis
A scatterplot divides the day into time blocks and records the occurrence of behavior during each block. This method reveals temporal patterns that may suggest environmental variables associated with the behavior, such as specific times of day, settings, or activities.
Functional Analysis
A functional analysis (FA) is the most rigorous method for identifying behavioral function. Developed by Iwata and colleagues in 1982/1994, a functional analysis systematically manipulates antecedent and consequence variables across standardized test and control conditions.
Standard Conditions
The standard functional analysis includes four conditions:
- Attention - The therapist provides brief attention (verbal reprimand, comfort) contingent on the target behavior. During non-behavior periods, the therapist redirects attention elsewhere.
- Escape - The therapist presents demands and removes them for a brief period contingent on the target behavior. If no behavior occurs, demands continue.
- Tangible - A preferred item is removed, then returned contingent on the target behavior.
- Alone/Control - The individual is alone with no demands, no social attention, and access to moderately preferred items. This condition tests for automatic reinforcement.
Modified Functional Analysis Approaches
The standard FA is not always practical in every setting. Brief functional analyses, trial-based functional analyses, and latency-based functional analyses offer alternatives that can be conducted in less time or in more naturalistic settings while still providing useful functional information.
Linking Assessment to Intervention
The FBA results directly inform intervention selection. Function-based interventions are consistently more effective than non-function-based interventions. For example:
- Attention-maintained behavior - Noncontingent attention, differential reinforcement of alternative behavior (DRA) using appropriate attention-seeking behaviors
- Escape-maintained behavior - Demand fading, functional communication training (FCT) teaching appropriate request-for-break behaviors, modifying task demands
- Tangible-maintained behavior - FCT teaching appropriate requesting, choice-making opportunities, visual schedules
- Automatically maintained behavior - Environmental enrichment, competing stimuli, response blocking (when safe and appropriate)
The FBA is not a one-time event. Behavior analysts should continue collecting data during intervention to verify that the hypothesized function was correct and that the intervention is producing the desired outcomes.