Functional Communication Training rests on a simple premise: challenging behaviour usually works. It gets attention, ends a demand, or produces a preferred item — and a behaviour that reliably works is very hard to displace. FCT begins with a functional assessment to establish what the behaviour is achieving, then teaches a communication response — a phrase, a sign, a picture card, a button press on a device — that achieves exactly the same thing, faster and with less effort. The idea that behaviour is communication is often stated loosely; FCT is the version with an evidence base behind it.

The approach was first demonstrated in 1985, when researchers showed that teaching children phrases matched to the function of their behaviour reduced that behaviour, while teaching phrases that earned the wrong outcome did not. Four decades of research have followed, including large series of consecutive clinical cases. This synthesis pulls that evidence together; the studies it draws on are listed at the end.

Components and variations

FCT is less a single procedure than a package, and the research is clearest about which parts of the package carry the weight.

  • Functional assessment comes first. The original demonstration hinged on matching the communication to the function: a phrase that recruited attention helped only when the behaviour was attention-maintained. More recent work has built treatments on briefer, interview-informed assessments that combine suspected functions into a single analysis, with strong results for children with autism — a practical shift away from lengthy standard functional analyses.
  • Extinction is usually part of the package. Comparative work suggests FCT is far more reliable when the old behaviour stops producing its usual outcome. A summary of 21 inpatient cases found FCT without extinction largely ineffective, and a later analysis of 58 applications reached a similar conclusion about reinforcement-based variations. Where extinction is unsafe or impractical, making the communication response markedly easier and quicker than the behaviour appears to matter even more.
  • Response modality is flexible. Speech, signs, picture cards, and speech-generating devices have all worked. What seems to decide the outcome is effort and recognisability: the response must be quick, easy, and understood by everyone the child encounters. Assistive devices have a particular advantage here — an unfamiliar adult can honour a device press when they might miss an idiosyncratic sign, which helps the new skill recruit natural reinforcement.
  • Schedule thinning is where gains are won or lost. Honouring every request is the right starting point and an unsustainable end point. Studies of thinning — including an analysis of 25 consecutive applications — suggest challenging behaviour tends to resurface during this transition, and that multiple schedules with clear signals for when requests will and won’t be honoured protect treatment gains while the schedule is stretched to something a classroom or home can actually deliver.
  • Tolerance is taught, not assumed. Contemporary FCT packages treat waiting and accepting “no” as explicit teaching targets, layered in gradually after the communication response is strong, rather than leaving the child to discover denial the hard way.
  • Caregivers can deliver it. Long-term home-based work with parents as implementers has produced durable reductions, and telehealth studies have shown parents can be coached remotely to run functional analyses and FCT with young children with autism — at a fraction of the cost of clinic delivery.

How strong is the evidence

The base under FCT is deep but has a particular shape. It rests on rigorous single-case experimental designs, replicated hundreds of times, and on large consecutive case series from clinical programmes — 21, 25, and 58 applications in the series drawn on here — rather than on group randomised trials. Reviews of that literature consistently classify FCT as one of the best-supported function-based treatments for challenging behaviour. This page is an evidence synthesis of that work, not an exhaustive appraisal of every study.

A few honest caveats:

  • Most of the strongest data come from clinical settings. Inpatient units and university clinics are well represented; ordinary classrooms less so. The telehealth and home-based work is encouraging, but effectiveness outside specialist supervision is the newest part of the literature.
  • Relapse is common and partly predictable. When reinforcement is thinned too fast, or the new response briefly stops working, the old behaviour tends to return. This is an argument for planned thinning and signalled availability, not a reason to write the approach off.
  • Generalisation is not automatic. Gains made with one adult in one room do not reliably transfer; maintenance appears to depend on the communication response being recognisable and honoured across settings and people.
  • It is an individual intervention. FCT is built on one child’s assessment. For class-wide disruption, a group contingency such as the Good Behaviour Game is the better-evidenced fit; the two solve different problems.

Frequently Asked Questions

What is Functional Communication Training?

Functional Communication Training is a behaviour intervention that starts with a functional assessment to find out what a challenging behaviour achieves, then teaches a communication response — a phrase, sign, picture card, or device press — that achieves the same thing. Because the new response works faster and more reliably than the old behaviour, the behaviour loses its purpose. It was first demonstrated in 1985 and has since become one of the most researched function-based interventions in behaviour analysis.

Does FCT work without extinction?

Sometimes, but far less reliably. Comparative studies suggest that when the old behaviour keeps producing its usual outcome, FCT often fails unless the communication response is considerably easier and more efficient than the behaviour it replaces. In practice, plans that stop reinforcing the challenging behaviour while honouring the new communication hold up much better.

What is reinforcement schedule thinning and why does it matter?

Early in FCT, every communication response is honoured immediately, which is not sustainable in a classroom or a busy home. Schedule thinning is the gradual, planned move from that dense schedule to a realistic one, often using clear signals for when requests will and will not be honoured. Research on consecutive clinical cases suggests this transition is where treatment gains are most often lost, so it deserves as much planning as the initial teaching.

Can parents and teachers run FCT themselves?

Yes, with coaching. Studies of home-based FCT show parents can implement it with strong results, and telehealth research has demonstrated that caregivers can be coached remotely at a fraction of clinic cost. The functional assessment that anchors the plan should still involve someone with behaviour-analytic training.