Every intervention used in ABA should have one thing behind it: evidence. At Aviation ABA, spanning ABA therapy in Riverton, Ogden, Roy, Layton and all over Utah, we believe families deserve to understand not only what works, but why it works. That is why we regularly review the research behind the strategies used in everyday therapy. One intervention that consistently stands out in the scientific literature is Functional Communication Training (FCT).
Since its introduction in the 1980s, FCT has been examined in hundreds of clinical studies involving children, adolescents, and adults with a wide range of communication and behavioral needs. Across those studies, one finding appears again and again: when individuals are taught an effective way to communicate what they need, challenging behaviors often decrease because communication becomes the easier and more successful option.
We spent time reviewing the foundational research behind Functional Communication Training, along with more recent evidence, to better understand why FCT continues to be considered one of the most effective evidence-based interventions used in modern ABA. Here are some of the most important insights that emerged.
The Origins of Functional Communication Training
Functional Communication Training was first introduced in 1985 by behavior analysts Edward G. Carr and V. Mark Durand. Their landmark research proposed a shift in how clinicians approached severe challenging behaviors.
Instead of asking, “How do we stop this behavior?” they asked a different question:
“What is this behavior communicating?”
This distinction fundamentally changed intervention planning.
Carr and Durand demonstrated that many challenging behaviors function as forms of communication. If an individual lacks an efficient, reliable way to request attention, escape difficult tasks, obtain preferred items, or communicate discomfort, challenging behavior may become the method that consistently produces those outcomes.
Their research showed that when individuals were taught an appropriate communicative alternative that served the same function as the challenging behavior, rates of problem behavior often decreased substantially while communication skills increased. That principle continues to form the scientific foundation of FCT today.
The Behavioral Science Behind FCT
At its core, Functional Communication Training is based on one of the central principles of behavior analysis: behavior is influenced by its consequences. Every behavior serves a purpose, even when that purpose is not immediately obvious.
Behavior analysts often classify behavioral functions into four broad categories:
- Access to tangible items or preferred activities
- Access to social attention
- Escape or avoidance of demands
- Automatic or sensory reinforcement
FCT begins by identifying which of these functions maintains a particular behavior.
Once the maintaining consequence has been identified, clinicians teach a communicative response that allows the individual to obtain the same outcome without engaging in challenging behavior.
From a behavioral perspective, this process is known as functional equivalence. The replacement communication produces the same reinforcement as the original behavior, making it more likely that the individual will choose communication over problem behavior in future situations.
Why Functional Assessments Come First
One reason FCT has demonstrated strong outcomes across research studies is that it does not begin with intervention. It begins with assessment. Behavior analysts first conduct a Functional Behavior Assessment (FBA) to identify the environmental variables maintaining behavior.
Assessment may involve:
- Direct observation
- ABC (Antecedent-Behavior-Consequence) data collection
- Caregiver interviews
- Teacher reports
- Experimental functional analyses when appropriate
Without understanding behavioral function, clinicians risk teaching communication that does not actually solve the individual’s problem. For example, teaching a child to request a break will likely have little effect if the challenging behavior is actually maintained by access to attention rather than escape from tasks. The accuracy of the assessment directly influences the effectiveness of the intervention.
Replacement Communication Must Be More Efficient Than the Behavior
One of the most interesting findings in behavioral research is that people naturally gravitate toward the response that requires the least effort while producing the desired outcome. Behavior analysts sometimes describe this as response efficiency. Imagine a child who throws materials during difficult work because adults consistently remove the task afterward.
If the replacement communication requires multiple sentences, several prompts, or extended waiting periods before receiving a break, the original behavior may remain more efficient. Effective FCT therefore emphasizes communication responses that are:
- Easy to perform
- Easily understood
- Immediately reinforced
- Appropriate for the individual’s current communication abilities
For some individuals this may involve spoken language. Others may communicate through:
- Gestures
- Picture Exchange Communication Systems (PECS)
- Communication boards
- Sign language
- Speech-generating devices
- Augmentative and alternative communication (AAC) systems
The specific communication method matters less than whether it reliably allows the individual to access the desired outcome.
Reinforcement Is What Makes FCT Work
The success of Functional Communication Training depends heavily on reinforcement. Teaching a communication response alone is not enough.
When an individual uses the newly learned communication, the requested outcome should consistently follow, particularly during the initial stages of intervention. This consistency allows the individual to learn that communication is now the most effective way to achieve their goal.
At the same time, clinicians carefully reduce reinforcement for the challenging behavior whenever it is safe and clinically appropriate to do so. From a behavioral standpoint, this changes the reinforcement contingencies surrounding both behaviors.
Over time, communication becomes more valuable because it consistently produces meaningful results, while challenging behavior becomes less effective.
Generalization Is a Scientific Goal, Not an Afterthought
One reason early behavior intervention research sometimes faced criticism was that newly acquired skills occasionally remained limited to therapy settings. Modern FCT places significant emphasis on generalization, ensuring that communication occurs across:
- Different environments
- Multiple communication partners
- Various activities
- Changing levels of support
Research has shown that generalization improves when communication is practiced naturally throughout daily routines rather than only during structured teaching sessions. This is why caregivers, teachers, siblings, and other support providers are often included in implementation whenever possible.
The objective is not simply teaching communication during therapy but ensuring those skills become part of everyday life.
What Research Says About Effectiveness
Over nearly four decades, Functional Communication Training has become one of the most extensively studied interventions within behavior analysis. Numerous single-case experimental studies, systematic reviews, and meta-analyses have demonstrated that FCT can significantly reduce challenging behaviors while increasing functional communication across a wide range of ages, diagnoses, and settings.
Research has reported positive outcomes for individuals with:
- Autism spectrum disorder
- Intellectual and developmental disabilities
- Language delays
- Multiple developmental conditions associated with challenging behavior
Although outcomes vary depending on assessment quality, treatment fidelity, reinforcement procedures, and individual differences, the overall body of evidence consistently supports FCT as an evidence-based behavioral intervention.
This growing research base is one reason FCT continues to appear in clinical practice guidelines and professional recommendations within ABA.
Common Misconceptions About Functional Communication Training
Despite its widespread use, several misconceptions about FCT continue to circulate. One misconception is that FCT simply teaches children to “use their words.”
In reality, communication is individualized. Spoken language is only one of many possible communication methods. Another misconception is that communication training alone automatically eliminates challenging behavior.
The research suggests otherwise. FCT is most effective when functional assessment, appropriate reinforcement, generalization strategies, and ongoing data collection work together as part of a comprehensive intervention plan.
Finally, some assume that FCT focuses only on young children. In practice, functional communication can be taught throughout childhood, adolescence, and adulthood whenever communication challenges interfere with meaningful participation in daily life.
Why FCT Continues to Influence Modern ABA
Few behavioral interventions have influenced clinical practice as profoundly as Functional Communication Training. Its lasting impact stems from a simple but scientifically powerful principle: communication often serves as a more effective and socially meaningful alternative to challenging behavior when it provides access to the same outcomes.
Rather than asking individuals to suppress behavior without offering another solution, FCT emphasizes teaching skills that improve both independence and quality of life.
As research continues exploring communication, behavior, and learning, Functional Communication Training remains an excellent example of how evidence-based science can translate into practical strategies that benefit individuals across home, school, clinic, and community environments. More than forty years after its introduction, its core principle remains just as relevant today: understanding the function of behavior is the first step toward teaching a better way to communicate.
