ABA glossary
Functional behavior assessment
Also called FBA
Definition
A process for identifying the variables that reliably predict and maintain problem behavior, using indirect assessment, descriptive assessment, and, when needed, functional analysis. Its product is a hypothesis about the behavior's function that guides treatment.
In plain words
An FBA answers two questions: when is the behavior likely to happen, and what does it get the person? The process usually moves from indirect methods (interviews, rating scales, records), to direct observation in the natural setting (ABC data, scatterplots), to a functional analysis when the function is still unclear or the stakes are high. The goal is not a label but a function, such as attention, escape, access to tangibles, or automatic reinforcement, so the team can design a plan that teaches a replacement behavior producing the same outcome.
Example from a session
For Jamal's hitting at school, the BCBA interviews his teacher and mother, then asks the RBT to collect ABC data during class for a week. The RBT records each hit with what happened right before and right after, using the definition in the plan. Most hits follow a new worksheet and are followed by Jamal being sent to a quiet corner. The BCBA uses these data to form an escape hypothesis.
For BCBA candidates and supervisors
Analysts treat indirect and descriptive results as hypotheses, because they show correlations, not causes; attention, for example, often follows problem behavior in natural settings regardless of function. A functional analysis is the only FBA component that tests causation by manipulating variables, so analysts weigh its benefits against risk, time, and setting constraints, and use safer variations (brief, trial-based, latency-based, precursor) when needed. Cultural and family context shape what information is gathered and which goals are acceptable. Function-based treatment tends to be more effective and less restrictive than default consequence procedures.
Often confused with functional analysis, descriptive assessment
FBA is the whole assessment process; functional analysis is one possible part of it, in which the analyst arranges test and control conditions to show which consequence maintains the behavior. Descriptive assessment observes natural events without changing them. A stem in which someone deliberately arranges conditions describes an FA, not FBA in general.
Exam tip
The typical sequence is indirect, then descriptive, then a functional analysis if needed. If a stem asks what an RBT does in an FBA, the answer is collecting data or running conditions as directed, not choosing the function or the intervention.
Can you spot functional behavior assessment in a scenario?
Practice RBT B.3 with exam-style questions and instant feedback.