What is functional communication training (FCT)?
Functional communication training (FCT) is a function-based intervention that teaches a learner a communication response producing the same outcome as a challenging behavior, so the need behind the behavior can be met a better way.
FCT starts from the finding that most challenging behavior works - it reliably produces attention, escape from a demand, or access to something the learner wants. If the behavior is a request made in the only form available, the treatment is to give the learner a form that works better, not simply to block the one they have.
That makes assessment the first step rather than an optional one. The function has to be identified before the replacement can be chosen, because the whole procedure depends on the new response earning the same outcome the behavior earned. Teaching a learner to ask for attention when the behavior was maintained by escape trains a response nobody will honor, and the original behavior stays exactly as useful as it was.
The replacement response has to beat the behavior on the learner's terms, which usually means it has to be easier, faster, and more reliable. Modality follows the learner's current repertoire rather than a preference for speech - a vocal phrase, a single word, a sign, a picture exchange, or a device can all serve, and a response that takes less effort than the behavior is the one that will actually compete with it.
Two things run in parallel once teaching begins. The new response is prompted and reinforced densely enough to establish it, while the challenging behavior stops producing the outcome it used to produce. Reinforcing only the replacement is usually not enough on its own, and withholding reinforcement for the behavior without first building a working alternative is both less effective and harder to justify.
Early density is deliberate but temporary. A response honored every time it occurs will occur constantly, so once it is established the schedule is thinned and the learner is taught to tolerate delay and occasional denial - waiting after a request, accepting 'not right now', continuing to work between reinforcers. This is the stage programs most often skip, and it is why an FCT plan that looked successful in session can fall apart in a classroom that cannot answer every request immediately.
It also has to hold outside the room where it was taught. Everyone who interacts with the learner needs to recognize the response and respond to it consistently, which makes caregiver and staff training part of the intervention rather than a follow-on, and it means the communication form has to travel - a device left in a bag or a picture book that stays at the clinic quietly reverts the learner to what worked before.
The evidence that FCT is working is two data paths on one timeline: the replacement response going up and the challenging behavior coming down. Tracking only the behavior can show suppression without communication, and tracking only the new response can show a skill the learner uses while the old behavior continues unchanged - the pair is what tells the supervising clinician whether the plan has actually shifted anything.