Functional communication training (FCT) is an evidence-based behavioral intervention that replaces problem behaviors like aggression, tantrums, or self-injury with an appropriate way to communicate the same need. The core idea is simple: if a child hits because they want a break from a difficult task, you teach them to ask for a break instead. The new communication skill and the old problem behavior serve the same purpose, but one is socially acceptable and the other isn’t.
FCT was first developed by Edward Carr and V. Mark Durand in 1985, based on a powerful insight: many challenging behaviors are essentially nonverbal communication. A child who screams during homework may be “saying” the work is too hard. A child who bites during circle time may be “saying” they want attention. Once you figure out what the behavior is communicating, you can teach the person a better way to say it.
How FCT Works Step by Step
FCT starts with a functional behavior assessment, which identifies why the problem behavior is happening. Behavior generally falls into a few categories of purpose: getting attention, escaping a demand, obtaining a preferred item, or meeting a sensory need. The assessment pinpoints which of these is driving the behavior in a specific situation. This step matters because if you guess wrong about the function, the replacement you teach won’t stick.
Once the function is clear, a replacement communication response is selected. This is the most critical design decision in FCT: the new skill must serve the exact same function as the unwanted behavior. If a child throws materials to escape math problems, the replacement might be handing a teacher a card that says “break, please.” If a child screams to get a parent’s attention, the replacement might be tapping the parent’s arm or pressing a button on a speech device. The form of communication can vary widely, but the function has to match.
Teaching typically involves structured practice sessions where the learner repeatedly uses the new communication response and immediately gets the outcome they want. At the same time, the old problem behavior stops working. This combination, reinforcing the new behavior while putting the old one on extinction, is what makes FCT effective. The learner discovers that asking works and that hitting, screaming, or biting no longer does.
Why It Works So Well
FCT is rooted in a behavioral principle called differential reinforcement of alternative behavior. In plain terms, you’re making the replacement behavior the only reliable path to what the person wants. Function-based interventions like FCT typically reduce destructive behavior by at least 90%, and they outperform similar behavioral treatments that aren’t informed by a functional assessment.
Carr and Durand’s original 1985 study demonstrated this clearly. They first identified that low adult attention and high task difficulty were the triggers for problem behavior in four children with developmental disabilities. Then they taught the children to verbally request attention or help, depending on what was driving their behavior. The result was reliable, replicable suppression of aggression, tantrums, and self-injury across all four children. The logic held: if problem behavior and communication serve the same function, strengthening one weakens the other.
Who Benefits From FCT
FCT is most widely used with individuals who have developmental disabilities, including autism, intellectual disabilities, and Down syndrome. It’s considered an established evidence-based practice for treating problem behavior in these populations. The approach works across ages, from young children just developing communication skills to adults in residential settings.
The intervention is especially valuable for people with limited verbal language, since it doesn’t require speech. But it’s also used with individuals who can talk but default to problem behavior in certain situations because it has historically been more effective at getting their needs met.
Communication Methods Used in FCT
The replacement behavior in FCT doesn’t have to be spoken words. Practitioners choose a communication mode that fits the person’s current abilities, and options range from no-tech to high-tech.
- Spoken language: Simple verbal phrases like “help me” or “I need a break,” appropriate for learners who can already produce some speech.
- Sign language or gestures: Manual signs or simple gestures that can be performed quickly and recognized by caregivers.
- Picture exchange systems: Printed icons or photographs organized in a binder or on a board. The learner hands over a picture to make a request.
- Speech-generating devices: Tablet apps or dedicated devices where selecting an icon produces spoken output. These range from simple single-button devices to full vocabulary systems with hundreds of words.
The chosen method should be easy for the learner to use and easy for people around them to understand. A replacement behavior that takes too much effort or that caregivers don’t recognize will lose out to the faster, already-established problem behavior.
The Role of Extinction
In its most effective form, FCT pairs reinforcement of the new communication skill with extinction of the problem behavior. Extinction means the old behavior simply stops producing results. If a child used to get out of tasks by throwing things, throwing things no longer leads to a break. Only the new request does.
This combination is powerful, but extinction isn’t always practical or safe. When working with adults, for example, physically preventing someone from escaping a task (escape extinction) can create real risks for both the individual and the therapist. Research at Rutgers University demonstrated that a modified FCT procedure without extinction successfully reduced escape-maintained challenging behavior to near-zero levels in two adult males with autism, while also increasing on-task behavior. So while extinction makes FCT stronger, it isn’t always necessary.
Making Progress Last in Real Life
One of the biggest challenges with FCT happens after the initial training succeeds. During teaching, every appropriate communication attempt gets reinforced immediately. A child asks for a break and gets one right away, every time. But that’s not how the real world works. Teachers can’t honor every request the moment it happens. Parents sometimes need a child to wait.
This is where schedule thinning comes in: gradually increasing the time between a communication attempt and the reinforcement, so the person learns to tolerate delays. Several approaches exist for doing this.
In one common method, caregivers use visual signals to alternate between periods when requests will be honored and periods when they won’t be. The “not available” periods start very short and gradually get longer. Another approach adds small tasks between the request and the reinforcement, so a child might need to complete one more math problem before getting their break, then two, then three. A third method introduces progressively longer waits, often teaching a tolerance response like saying “okay” during the delay.
Schedule thinning is where many FCT programs hit a wall. Research on one common thinning method found that it achieved 90% or greater behavior reduction in about 43% of cases, and 80% or greater reduction in 64% of cases. When the reinforcement schedule was thinned without additional supports, roughly 37% of cases were unsuccessful. These numbers highlight that the transition from controlled teaching sessions to everyday life requires careful planning, and sometimes supplemental strategies, to maintain gains.
What Makes FCT Succeed or Fail
Several factors determine whether FCT produces lasting change. The replacement behavior needs to be easier and faster than the problem behavior. If asking for help takes more effort than screaming, screaming will win. The people in the learner’s daily life, parents, teachers, aides, need to respond consistently. FCT in its most effective form requires that implementers monitor both the communication behavior and the challenging behavior, reinforcing one and not the other with high fidelity. When caregivers inconsistently reinforce the old behavior, progress unravels.
The functional assessment also has to be accurate. If the team believes a child’s aggression is motivated by wanting attention, but it’s actually motivated by escaping noise, teaching the child to request attention won’t address the real need. The mismatch means the new behavior won’t reliably replace the old one, because it doesn’t serve the same function.
When these elements align, FCT is one of the most effective and most studied interventions for reducing challenging behavior in people with developmental disabilities. It treats problem behavior not as something to simply suppress, but as communication to be understood and redirected.