By Matt Harrington, BCBA · Behaviorist Book Club · April 2026 · 12 min read

Functional Communication Training: Theoretical Foundations and Clinical Application with Dr. Wayne Fisher

Overview & Clinical Significance

Functional Communication Training is among the most well-supported and widely implemented interventions in applied behavior analysis. Developed through the foundational work of Carr and Durand in the 1980s and extended by Dr. Wayne Fisher and colleagues at the Munroe-Meyer Institute, FCT addresses challenging behavior at its functional root — teaching an efficient, socially appropriate communicative response that produces the same reinforcement as the problem behavior.

Dr. Fisher's contributions to FCT include refinements in the understanding of the matching law as it applies to competing response allocation, the role of reinforcement schedule parameters in FCT effectiveness, and the challenges of treatment generalization and durability across clinical and natural environments. His work has substantially advanced the field's understanding of why FCT works, not merely that it works, providing a theoretical foundation that enables practitioners to predict and troubleshoot FCT outcomes with greater precision.

For BCBAs, FCT is not simply a technique to apply — it is a clinical framework that requires accurate functional assessment, careful communicative response selection, precise reinforcement schedule design, and systematic generalization and maintenance programming. This video presentation offers the perspective of one of the field's leading experts on how FCT was developed, how it has evolved, and how it should be applied in clinical settings for individuals with ASD and related conditions.

Understanding FCT's theoretical underpinnings — particularly the competing operants framework borrowed from the behavioral economics literature — allows practitioners to design FCT programs with greater precision and to anticipate the conditions under which FCT may fail. This theoretical fluency is what separates practitioners who implement FCT effectively from those who follow the procedure mechanically without understanding the principles that make it work.

Background & Context

The foundational insight behind FCT is deceptively simple: if challenging behavior is maintained by access to specific reinforcers, then any behavior that produces those same reinforcers could theoretically compete with the challenging behavior. FCT instantiates this insight by identifying the functional reinforcer through assessment, teaching a communicative response that produces that reinforcer, and arranging the environment so that the communicative response is both more efficient and more effective than the challenging behavior.

Carr and Durand's original 1985 research demonstrated that teaching functionally appropriate communication reduced challenging behavior — a finding that was theoretically predicted but empirically novel at the time. They showed that only communicative responses matched to the function of the challenging behavior were effective, providing early evidence that functional assessment was a necessary prerequisite to effective behavioral intervention.

Fisher's subsequent contributions deepened the understanding of the mechanisms driving FCT effectiveness. His work drew on the matching law — the principle that behavior allocates proportionally to the relative reinforcement available for competing responses — to explain why FCT produces behavior reallocations rather than mere suppression. When the communicative response produces richer, more immediate reinforcement than the challenging behavior, behavior allocates toward communication. This framework predicts specific outcomes from changes in reinforcement schedule parameters and provides a principled basis for schedule design decisions.

The generalization of FCT outcomes to natural environments has been an ongoing focus of Fisher's work. FCT trained in clinical settings often shows limited transfer to home, school, and community contexts because the reinforcement schedules and prompt support available in natural environments differ substantially from those in the training setting. Developing maintenance and generalization protocols — including the systematic thinning of FCT reinforcement schedules while maintaining low levels of challenging behavior — has been a major clinical challenge that Fisher's program has addressed through systematic research.

Clinical Implications

The first clinical implication of FCT's theoretical foundation is that functional assessment is non-negotiable. FCT trained on an incorrect functional hypothesis will either fail entirely or produce a communicative response that competes with the reinforcement maintaining a different topography of the problem behavior. If challenging behavior is maintained by escape from demands but FCT teaches a response that produces attention, the escape-maintained behavior will persist. Code 2.01 and the standard of evidence-based practice both require that functional assessment precede FCT design.

Communicative response selection is a critical decision in FCT design. The selected response must be within the learner's current repertoire or trainable within a reasonable timeframe, must be recognizable by natural communication partners, and must be more efficient than the challenging behavior on key parameters including response effort, reinforcer delay, and reinforcer quality. Fisher's work has examined the efficiency principle in detail, demonstrating that when the FCT response requires more effort than the challenging behavior, behavior continues to allocate toward the challenging behavior even when the FCT response is reinforced.

Reinforcement schedule parameters — particularly the density and delay of reinforcement for the FCT response — require careful management across the phases of treatment. In the initial training phase, a very dense reinforcement schedule (typically continuous reinforcement, CRF) is used to establish the communicative response and build its reinforcement history. Subsequent phases involve systematic schedule thinning, which risks producing resurgence of challenging behavior if conducted too rapidly or without adequate schedule fading procedures. Fisher's research on schedule thinning provides specific guidance on how to reduce FCT reinforcement schedule density while maintaining suppression of challenging behavior.

Generalization programming must address the multiple dimensions along which FCT must transfer: across settings, across communication partners, across motivating operation states, and across response variations. A learner who uses a PECS card to request a break in a structured therapy room may not generalize this to the classroom if teachers are not trained as communication partners and if the classroom environment does not include the same prompt support available in therapy.

Ethical Considerations

The ethical foundation of FCT is the principle that individuals have a right to effective communication — and that when challenging behavior is the only communication available, it represents not merely a behavioral problem but a systemic failure to teach functional alternatives. This framing is consistent with the rights-based PBS framework and with the BACB Ethics Code's requirement under Code 2.01 to provide effective treatment.

Code 6.01's least-restrictive principle is directly implicated in FCT's primacy as the intervention of choice for function-maintained problem behavior. FCT is inherently less restrictive than consequence-based procedures because it expands the individual's behavioral repertoire rather than constraining it. When consequence-based procedures are considered, they should be considered only as supplements to FCT — after FCT has been attempted with fidelity and found insufficient — not as alternatives to it.

The process of schedule thinning in FCT raises ethical questions about the conditions under which reinforcement can be legitimately reduced. Fisher's research frames schedule thinning as clinically necessary for generalization and maintenance but requires it to be conducted carefully and monitored continuously. Rapid or insensitive schedule thinning that produces resurgence of severe problem behavior is both clinically counterproductive and ethically concerning. The monitoring obligation under the Ethics Code — reviewing treatment data regularly and modifying procedures when data indicate inadequate outcomes — applies directly to schedule thinning phases.

For learners who use augmentative and alternative communication devices as their FCT response modality, ensuring that devices are maintained, available, and functional at all times is an ethical obligation. A learner whose device is not charged, has been left at home, or has a failed speech output component has been deprived of their primary communication modality. BCBAs who have prescribed AAC devices as FCT responses bear responsibility for ensuring the communication partners and systems supporting those devices are in place.

Assessment & Decision-Making

FCT program design begins with a functional behavior assessment of sufficient rigor to identify the reinforcement function — or functions — maintaining the challenging behavior. For behaviors with clear and consistent functional assessment outcomes, an indirect/descriptive assessment may be sufficient to proceed with FCT design. For behaviors with ambiguous functions, multiple functions, or high intensity that limits the safety of naturalistic observation, a functional analysis — the experimental manipulation of antecedent and consequence conditions — may be needed to isolate the maintaining contingency.

Once the function is identified, communicative response selection involves weighing several factors: the learner's current communication modality (vocal, AAC, gesture), the effort required by candidate responses, the recognizability of the response by diverse communication partners, and the availability of the response across the relevant environments. Fisher's efficiency principle suggests selecting the lowest-effort response that can be made reliably distinct from other communicative behavior and trained to mastery quickly.

Schedule thinning decisions should follow a systematic protocol. A common approach involves fixed-ratio thinning — gradually increasing the number of FCT responses required per reinforcer delivery — while monitoring problem behavior as the probe measure. The thinning pace is determined by the data: if problem behavior remains at or near zero, thinning continues; if problem behavior increases, the schedule is returned to the prior ratio and thinning is slowed. Fisher's research supports chained schedule approaches as an alternative that may produce better maintenance of suppression through thin schedules.

Generalization probes should be conducted in at least two naturalistic settings before FCT is considered clinically complete. Probes should assess not only whether the communicative response occurs but whether it produces the target reinforcer from natural communication partners without clinician prompting, and whether problem behavior rates remain low in the absence of intensive clinical support.

What This Means for Your Practice

FCT is probably the most important single intervention in your clinical toolkit for problem behavior maintained by social contingencies. Understanding it at the theoretical level — not just the procedural level — allows you to troubleshoot when it is not working, to anticipate when resurgence is likely, and to design schedule thinning and generalization protocols that are individually calibrated rather than formulaic.

If you are implementing FCT programs currently, ask yourself these questions: Is the functional hypothesis that drives each FCT program supported by systematic assessment data? Is the communicative response more efficient than the challenging behavior on effort, delay, and quality dimensions? Has the reinforcement schedule been thinned systematically with data-based decision criteria, or was it thinned arbitrarily? Has generalization been assessed across settings and communication partners with data?

For supervisors, FCT is a core competency that should be addressed explicitly in your supervision curriculum. BTs who implement FCT need to understand the function they are reinforcing, the response they are reinforcing, and the schedule parameters in place — not merely the physical mechanics of delivering a reinforcer when the card is exchanged. Building conceptual understanding of FCT mechanisms in your supervisees is an investment that pays dividends in implementation fidelity and in the quality of clinical problem-solving when a program is not working.

Dr. Fisher's career represents one of the most productive applications of basic behavioral science to severe problem behavior in the ABA field. Engaging with his published work — in JABA and related journals — provides access to the most rigorous empirical foundation available for FCT practice. Practitioners who read the primary literature on FCT, rather than relying exclusively on textbook summaries, develop a more nuanced and powerful clinical understanding of the procedures they implement daily.