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Functional communication training: the role of speech pathologists and behavior analysts in serving students with autism.


Autism is a neurological disorder characterized by significant impairments in language/communication, deficits in social interaction and restricted interests/ stereotypical behavior (American Psychiatric Association, 1994). Perhaps the most central of these impairments, especially in young learners, is the communication deficit. Learners with autism have difficulty in all aspects of communication, including receptive understanding, expressive language, and comprehension. Even in learners with a well-established capacity to communicate, there are often very significant deficits in spontaneous communications, in complex communication, and in reciprocal communication.

These deficits in communication and social skills place these learners at risk for developing significant behavior problems. Learners with autism often engage in stereotypical behavior (e.g., repetitive, non-goal directed behavior), aggression, self-injurious behavior (SIB), pica, elopement, disruption, property destruction, and inappropriate vocalization (Kelli Dominick, Ornstein Davis, Lainhart, Tager-Flusberg, & Folstein, 2007; Smith, Vollmer & St. Peter Pipkin, 2007). Research has indicated that the ability to communicate is often directly related to the prevalence of maladaptive behavior (Carr & Durand, 1985). In many cases, challenging behavior serves a communicative function. In the absence of more effective means of communicating wants and needs, learners with autism often communicate through aberrant behavior. Learners with autism will often engage in disruptive behavior to access positive reinforcement (e.g., access to tangibles, access to attention) or to access to negative reinforcement (e.g., escape from demands, escape from a sensation).

Given the detrimental nature of maladaptive behaviors and their negative impact on social and academic functioning, it is essential for learners with autism to receive intensive intervention to address their communication deficits at the earliest available opportunity. Intervention to address communication deficits should be an integral part of both Speech/Language and Behavior Analytic programs. Challenging behavior and its relationship to the ability to communicate highlight the importance of collaborative interaction between SLPs and behavior analysts.

Historically, speech pathologists and behavior analysts have both served the needs of learners on the autism spectrum. The alliance has not always been an easy one, as the disciplines sometimes approach language acquisition differently. However, increasingly, there have been attempts to bridge these two communities of professionals, as a joint and integrated approach can maximize success. Collaboration between these two fields promotes comprehensive programming, which maximizes the scope and quality of services provided to learners with autism.

Addressing communication deficits

When addressing communication deficits, practitioners need to consider two important factors during the intervention process, the modality for communication and the procedures for teaching the response(s). A considerable amount of evidence has shown that learners with autism may respond to a variety of different modalities of communication. For instance, learners with autism have been taught to effectively communicate using verbal speech, (e.g., Carr & Durand, 1985), sign language (Mirenda, 2003), picture exchange (e.g., Yoder & Stone, 2006) and electronic augmentative devices (e.g., Millar, Light & Schlosser, 2006). It is important for practitioners to account for the strengths and weaknesses for different learners as well as the environment that the learners exist to choose an appropriate communication modality. For instance, teaching communication through verbal speech may not be appropriate for a learner with severe apraxia. Low functioning learners may respond better to picture exchange systems as they provide visual prompts for communication.

The communication deficits of learners with autism have been addressed through a number of instructional approaches. Goldstein (2002) reviews that sign language, discrete trial training, and milieu approaches have all been demonstrated to expand communicative skill repertoires. Discrete trial training can be used to facilitate communicative skills in any modality. It can be utilized to teach vocal, sign, or augmentative responses, as well as to teach combinations of these responses. Total communication approaches (incorporating a variety of communicative topographies) have been shown to build receptive and expressive vocabulary. Individuals with poor verbal imitation skills appear to do less well with vocal-only approaches (Goldstein, 2002), supporting a mixed approach. Discrete tria l training literature has demonstrated the capacity for teaching sophisticated communication skills, and has become increasingly focused on the transfer of those effects to natural environments and contexts.

In addition, DTI effectively establishes learning readiness skills by teaching the learner to attend to the instructor and the materials. This helps to increase the effectiveness of instruction in speech and language. It may also be the case that DTI is especially important in building early skills in communication, and that more naturalized methods have more relevance for later application and generalization of established skills (Carr & Kologinsky, 1983). A combined approach, which utilizes both the formality of DTI and the looseness of naturalistic instruction, may result in greater language gains for learners.

A number of themes in language instruction have been identified. A focus on spontaneity and initiation is of central importance to social functioning and integration (e.g., Koegel, 2000; Prizant & Wetherby, 1998). Other themes include the importance of developing pragmatic skills in language, ensuring family involvement and the coordination of efforts between home and school, and analyzing the interrelationships between language and behavior (e.g., Koegel, 2000; Lord, 2000).

Another central aspect of language intervention has been teaching communication as a means of controlling one's environment (Goldstein, 2002.) It has been repeatedly demonstrated that teaching communicative behaviors is associated with a reduction in challenging behaviors. The process of teaching communicative responses to replace maladaptive behavior is often referred to as Functional Communication Training (FCT).

Teaching Functional Communication to Learners with Autism Spectrum Disorders

As mentioned previously, learners with ASDs often engage in various forms of maladaptive behavior. Some topographies of behavior are stereotypical or ritualistic in nature and represent the core features of autism. Other associated topographies of maladaptive behavior include self-injurious behavior, aggression, tantrums, and property destruction, among a variety of other types of behavior. These topographies of maladaptive behavior often interfere with effective learning.

Automatically reinforced behavior, commonly associated with core features of autism, include repetitive behavior (e.g., rocking, hand flapping), and ritualistic behavior (e.g., lining objects up, eating specific foods). These types of behavior are generally repetitive and presumably non-goal oriented. Repetitive and ritualistic behaviors are often associated with a biological etiology. In other words, the behavior is inherently reinforcing to learners on the autism spectrum and is not related to any external environmental reinforcement contingency.

Often, the occurrence of maladaptive behavior is related to environmental events. Maladaptive behavior is generally maintained by either positive or negative reinforcement. Individuals will sometimes engage in disruptive behavior to access social attention and/or tangible items. They will also frequently engage in challenging behavior to escape from demands or to escape from a sensation (e.g., noise).

In general, the cause, or the function, of maladaptive behavior, is best determined by conducting a functional behavior assessment (FBA). Functional assessments generally involve using intervie ws, behavioral observation, and at times, environmental manipulations to determine the function of disruptive behavior. When the function of disruptive behavior has been elucidated, practitioners can often teach the learner to access the reinforcer maintaining disruptive behavior (e.g., attention, escape) using an adaptive form of communication. Selecting the modality of the replacement response is a vital component to effective functional communication training. The response must be within the student's current ability level, efficient for the student in daily use, and reliably reinforced by others in the environment.

The expertise of both the behavior analyst and the speech therapist is essential in this context. The behavior analyst can assist in identifying the function(s) of the challenging behavior, and in determining an appropriate replacement skill. The speech therapist can help in identifying the modality likely to result in successful teaching and can target opportunities for instruction in natural contexts.

Functional Communication Training

Functional communication training (FCT) is an effective treatment method for many topographies of problem behavior (Carr & Durand, 1985; Fisher, Piazza, Cataldo, Harrell, Jefferson & Conner 1993; Hagopian, Fisher, Sullivan, Acquisto & LeBlanc, 1998). As mentioned previously, FCT involves identifying the function of challenging behavior then providing the individual with an adaptive, functionally-equivalent response to access reinforcement. A functionally-equivalent response is one that provides the same access to the same reinforcer for the learner, but through alternative response. For example, if a learner has a history of engaging in disruptive behavior to escape demands, practitioners can teach the learner to appropriately escape a demand by touching a break card or signing the word "break". Similarly, a learner who engages in disruptive behavior to access social attention can be taught to raise their hand or exchange a "Talk to me" card to request attention appropriately.

The seminal article for FCT was published in 1985 by Carr and Durand. In this study, the authors conducted functional analyses for four learners who displayed various topographies of maladaptive behavior. The results of the analyses indicated that the individual learners engaged in disruptive behavior for different reasons. Two of the learners engaged in disruptive behavior to escape from demands, one exhibited high rates of maladaptive behavior to access social attention, and one participant engaged in maladaptive behavior that was multi-operant in nature (attention and escape-maintained).

After conducting the functional analyses, the authors taught different communication responses to the learners. Specifically, they taught responses that were relevant to the function of behavior and irrelevant responses that were not linked to the function of challenging behavior. For instance, teaching a learner to request a break or help if maladaptive behavior is escape-maintained, would be considered a relevant response (matched to function). Teaching a learner with escape-maintained behavior to request attention would be teaching an irrelevant response. The results indicated that when participants were taught the relevant response linked to the function of behavior, disruptive behavior decreased and communication increased. In addition, the authors found that when irrelevant responses were taught, disruptive behavior persisted and communication remained low. These results indicated that, in many cases, maladaptive behavior can be replaced with functional communicative responses resulting from FCT. In addition, the results from this study highlighted the importance of linking the treatment to the function of challenging behavior.

When intervenin g with challenging behavior, understanding the efficiency of responding is critical (Horner & Day, 1991, Richman, Wacker & Winborn, 2001) . Failure to account for response effort, consistency of reinforcement, and immediacy of reinforcement compromises effectiveness of FCT. If an alternative communication response is difficult, or results in reinforcement more slowly or less consistently, it is not likely that the new response will replace maladaptive behavior. Thus, it is important that the behavior be thoroughly assessed for its function, that the right response is selected to train, and that it is trained appropriately and well.

Acquisition and Maintenance of an FCT response

During the initial training of an FCT response, it is important to account for several factors to ensure that the response is acquired. Specifically, practitioners must use both extinction and motivating operations effectively. Research has indicated that the acquisition of an FCT is most effective when combined with extinction for the target (maladaptive) behavior (Shirley, Iwata, Kahng, Mazaleski & Lerman, 1997; Kelley Lerman & Van Camp, 2002). The use of extinction to reduce behavior involves ensuring that the learner no longer garners reinforcement for the maladaptive behaviors that previously resulted in reinforcement. For example, if a learner engaged in attention-maintained disruptive behavior, an appropriate use of extinction would be to no longer provide attention in response to disruptive behavior. Acquisition of an alternative response is most successful when the maladaptive behavior targeted for reduction contacts extinction. If the target behavior still contacts reinforcement, it often interferes with the acquisition and maintenance of replacement skills (Shirley et al., 1997; Kelley et al., 2002).

Another important consideration in the acquisition and maintenance of an FCT response is accounting for motivating operations (Brown, Wacker, Derby, Peck, Richman, Sasso, Knutson & Harding, 2000). This process involves attending to the motivational state of the learner and ensuring that learning is done in the context of powerful natural motivators. This is of particular importance during the acquisition of FCT responses, because effective acquisition of a communication response is enhanced when practitioners account for the relative states of satiation and deprivation. For instance, a learner would be much more likely to acquire an "attention" request (e.g., "Talk to me") if the learner was highly motivated to access attention (e.g., following a period of deprivation from attention). Similarly, "escape" requests are much more likely to be evoked when presented with difficult demands, rather than being taught the response in the absence of such demands.

In addition, studies have evaluated the relative efficacy of FCT alone, FCT with extinction, and FCT with punishment (Fisher et al., 1993; Hagopian et al., 1998). These studies indicated that FCT alone was ineffective (when the both the target behavior and maladaptive behavior contacted reinforcement). Both studies indicated that FCT paired with either extinction or punishment was vastly superior to FCT alone. Both studies indicted that FCT with punishment produced the most robust treatment effects.

Best Practices with FCT

When training an FCT response, practitioners should start with a simple, desirable response to train. Practitioners may initially need to start with a non-vocal response that is easily prompted and gradually shape it as the response is acquired. The response that is trained should be related to a functional reinforcer. In other words, the communication response should be matched to the function of maladaptive behavior (e.g., requests for attention or escape). In addition, the target behavior (e.g., self injury, aggression) to be replaced should be well defined.

In the initial stages of intervention, practitioners should reinforce the communication response immediately and consistently (e.g., most to least prompting/errorless learning). The initial schedule of reinforcement should be dense in nature and faded over time (Wordsell, Iwata, Hanley, Thompson & Kahng, 2000). Reinforcement for maladaptive behavior should be eliminated. FCT should initially be paired with extinction for target behavior. In the event that extinction is not successful, punishment may be considered.

Clinical challenge: Issue of suppressing or expanding vocalizations

One of the challenges faced by clinicians implementing FCT (and more broadly by clinicians addressing communication training) is the fear that parents and teachers often have about building alternative modalities of communication. Parents, in particular, may fear that if a child can simply sign a response, exchange a picture, or touch a button they will never vocalize the response. SLPs and behavior analysts alike often encounter this fear, and it can be an impediment to implementing training alternative, communicative responses.

It is important for both communities of professionals to educate parents and teachers regarding these concerns. There is data that clearly indicate that these fears are unwarranted (e.g., Carr & Felce, 2006; Goldstein, 2002; Charlop-Christy, Carpenter, Le, LeBlanc, & Kelley, 2002). To the contrary, communication training in any alternative modality enhances vocal communication. In fact, the development of the functional ability to communicate has been associated with the emergence of vocal speech in children using the Picture Exchange Communication System (Bondy & Frost, 1994, 2001; Carr & Felce, 2006; Charlop-Christy, Carpenter, Le, LeBlanc, & Kelley, 2002). It is likely that the strengthening of an effective communication response supports the emergence of other communicative responses. It also often reduces frustration for the learner and provides opportunities for modeling social language, which may facilitate the emergence of vocal communication.

In addition, the development of functional requesting seems to have broader social impact. Individuals who develop functional mand repertoires via P.E.C.S also demonstrate increases in socio-communicative behaviors (Charlop-Christy, Carpenter, LeBlanc, & Kelley, 2002), reductions in challenging behaviors, and concomitant increases in other appropriate behaviors (Anderson, Moore, & Bourne, 2007).

Role definitions: How to maximize the contribution of each expert

Of course, there are parallels between the fields and overlap in the emphases of the disciplines of behavior analysis and speech therapy. While behavior analysts have made the identificatio n of such alternative communicative behaviors a central focus of their efforts, SLPs have discussed the utility of this approach for many years (Prizant & Wetherby, 1998). The team approach allows for a thorough examination of the functions of behavior as well as the identification of functional, replacement behaviors. Identification of these replacement behaviors and the development of procedures to teach these responses are shared goals of both SLPs and behavior analysts.

There is, in general, consensus between the fields on many aspects of intervention for individuals with ASD's. Both groups of professionals highlight the critical need to identify and train communicative responses to replace aberrant behaviors and focus on the need to match the learner with an efficient and effective modality of communication.

Some areas of overlap and/or of role ambiguity are commonly encountered between the disciplines of behavior analysis and speech therapy. Examples include: the identification of speech and language objectives, the identification of communicative learning opportunities, and staff training on interacting with learners with autism. As members of both disciplines focus on these areas, and bring separate expertise to the issues, some redundancy in treatment focus is inevitable.

The Role of the Speech Therapist

Speech and language pathologists (SLPs) are specifically trained in the mechanics of speech production and in the broad scope of language and communication goals. The speech therapist is often charged with the task of determining communication modality and with consulting to the team regarding language/communication issues. Increasingly, speech and language pathologists serve as consultants and trainers to teams of professionals working with children with autism. Much of their intervention is done within the classroom, in the actual environment in which the learner is expected to demonstrate skills. Furthermore, such an integrated service delivery model allows for modeling and demonstration of techniques and programs to other staff members. Defining the role of the speech therapist in this way ensures that student's speech and language goals are addressed consistently throughout the day and across all staff members.

Furthermore, such integration allows the SLP to assess the extent to which the learner is well matched to a particular communication modality (or combination of modalities.) It also provides time for the SLP to shape the communicative response into a form that will be reinforced by others.

The Role of the Behavior Analyst

Professional training for behavior analysts also includes training on the objective evaluation of learner progress and in the analysis of the function of challenging behaviors. Similar to the roles of speech therapists, behavior analysts also often work in consultative and training roles, taking the lead on the analysis and treatment of challenging behaviors and addressing issues in learning and skill acquisition (e.g., selection of targets and materials, identification of effective prompts, and assurance of generalization). Communication is inherently a focus of the behavior analyst as well, as it is so central to behavioral functioning, skill development, and social integration goals. In particular, behavior analysts (often in conjunction with SLP's) examine how individuals are communicating their wants and needs. As an extension of this analysis, behavior analysts also examine how aberrant behavior might be serving a communicative function, and seek to replace maladaptive behaviors with functional, alternative, communicative responses.

Areas of Influence

The specific expertise of each discipline can support more effective programming. While SLPs have the expertise to recommend specific modalities of communication, behavior analysts have identified learner characteristics that might be associated with a better match of learner to communication system (e.g., Frost & Bondy; Sundberg & Partington, 1998). While behavior analysts might lead the team in making data-based treatment modifications, SLP's might lead in bringing the skill into the natural environment. Together, the professionals can design an instructional environment that provides maximal opportunities to learn and practice the targeted skills.


Communication difficulties are a central aspect of autism spectrum disorders, and often result in maladaptive behavior patterns. Many interventions have been associated with success in the treatment of communication deficits in learners with autism. One of the challenges in meeting the needs of learners with autism spectrum disorders is identifying appropriate and functional alternatives to these challenging behaviors. The first essential ingredient is to understand the communicative value, or function, of the maladaptive behavior. In addition, the student must be taught an alternative response that effectively and efficiently replaces the problematic behavior.

The response selected must be easy for the child to engage in and must be within the current skill repertoire of the learner. In addition, training must ensure that sufficient reinforcement is available for the replacement response, and that reinforcement is no longer available for the previous, aberrant response.

While parents and professionals both seek to promote vocal communication, it is often best to begin with non-vocal responses, in the interests of efficiency, low response effort, and reduced learner frustration. Professionals should be clear with parents about the benefits of efficient and effective responding, and should share data with them regarding the likelihood that alternative communication methods will enhance vocal responding in learners with this capacity.

This is an area in which speech pathologists and behavior analysts can learn from one another. Collaboration between the disciplines can result in more effective programming, building communication skills and reducing behavioral challenges in the most expedient way. When implemented effectively, functional communication training yields results that are reinforcing to learners, their families, and the staff members who work with them. As the learner is reinforced by more successful interactions, aberrant behaviors diminish and social communication flourishes.


American Psychiatric Association (1994). Diagnostic and statistical manual of mental disorders (4th ed.). Washington DC.

Anderson, A., Moore, D., & Bourne, T. (2007). Functional communication and other concomitant behavior change following PECS training: A case study. Behavior Change, 24, 1-8.

Bondy, A. & Frost, L. (1994). The picture exchange communication system. Focus on Autistic Behavior, 9, 1-19.

Bondy, A. & Frost, L. (2001). The Picture Exchange Communication System. Behavior Modification, 25, 725-744.

Brown, K. A., Wacker, D. P., Derby, K. M., Peck, S. M., Richman, D. M., Sasso, G. M., Knutson, C. L., & Harding, J. W. (2000). Evaluating the effects of functional communication training in the presence and absence of establishing operations. Journal of Applied Behavior Analysis, 33, 53-71.

Buckley, S. D. & Newchok, D. K. (2005). Differential impact of response effort within a response chain on use of mands in a student with autism. Research in Developmental Disabilities, 26, 77-85.

Carr, E. G., & Durand, V. M. (1985). Reducing behavior problems through functional communication training. Journal of Applied Behavior Analysis, 18, 111-126.

Carr, D. & Felce, J. (2006). Increase in production of spoken words in some children with autism after PECS teaching to Phase III. Journal of Autism and Developmental Disabilities, 37, 780-787.

Charlop-Christy, M. H., Carpenter, M., Le, L., LeBlanc, L., & Kelley, K. (2002). Using the Picture Exchange Communication System (PECS) with children with autism: Assessment of skill acquisition, speech, socio-communicative behavior, and problem behaviors. Journal of Applied Behavior Analysis, 35, 213-231.

Dominick, K. C., Ornstein-Davis, N., Lainhart, J., Tager-Flusberg, H. & Folstein, S.(2007). Atypical behaviors in children with autism and children with a history of language impairment. Research in Developmental Disabilities, 28 (2), 145-162

Fisher, W., Piazza, C., Cataldo, M., Harrell, R., Jefferson, G., & Conner, R. (1993). Functional communication training with and without extinction and punishment. Journal of Applied Behavior Analysis, 26, 23-36.

Goldstein, H. (2002). Communication intervention for children with autism: A review of treatment efficacy. Journal of Autism and Developmental Disorders, 32(5), 373-96

Hagopian, L. P., Fisher, W. W., Sullivan, M. T., Acquisto, J., & LeBlanc, L. A. (1998). Effectiveness of functional communication training with and without extinction and punishment: A summary of 21 inpatient cases. Journal of Applied Behavior Analysis, 31, 211-235.

Horner, R. H., & Day, H. M. (1991). The effects of response efficiency on functionally equivalent competing behaviors. Journal of Applied Behavior Analysis, 24, 719-732.

Jayne, D., Schloss, P.J., Alper, S., & Menscher, S. (1994). Reducing disruptive behaviors by training students to request assistance, Behavior Modification, 18, 320-338.

Kelley, M. E., Lerman, D. C., & Van Camp, C. M. (2002). The effects of competing reinforcement schedules on the acquisition of functional communication. Journal of Applied Behavior Analysis, 35, 59-63.

Koegel, L.K. 2000. Interventions to facilitate communication in autism. Journal of Autism and Developmental Disorders, 30(5), 383-391.

Lord, C. (2000). Commentary: achievements and future directions for intervention research in communication and autism spectrum disorders. Journal of Autism and Developmental Disorders, 30(5), 393-398.

Millar, D. C., Light, J. C. & Schlosser, R. W. (2006). The impact of augmentative and alternative communication intervention on the speech production of individuals with developmental disabilities: A research review. Journal of Speech, Language, and Hearing Research, 49, 248-264

Mirenda, P. (2003). Toward a functional augmentative and alternate communication for students with autism: Manual signs, graphic symbols, and voice output communication aids. Language, Speech, and Hearing Services in Schools, 34, 203-216.

Prizant, B. M. & Wetherby, A. M. (1998). Understanding the continuum of discrete-trial traditional behavioral to social-pragmatic developmental approaches in communication enhancement for young children with autism/pdd. Seminars in Speech and Language, 19, 329-353.

Richman, D. M., Wacker, D. P., & Winborn, L. (2001). Response efficiency during functional communication training: Effects of effort on response allocation. Journal of Applied Behavior Analysis, 34, 73-76.

Shirley, M. J., Iwata, B. A., Kahng, S., Mazaleski, J. L., & Lerman, D. C. (1997). Does functional communication training compete with ongoing contingencies of reinforcement? An analysis during response acquisition and maintenance. Journal of Applied Behavior Analysis, 30, 93-104.

Smith, R. G., Vollmer, T. R. & St. Peter Pipkin, C. (2007). Functional approaches to assessment and treatment of problem behavior in persons with autism and severe disabilities. In P Sturmer & A. Fitzer (Eds.), Autism Spectrum Disorders: Applied Behavior Analysis, Evidence and Practice. (pp.187-234).

Wacker, D. P., Steege, M. W., Northup, J., Sasso, G., Berg, W., Reimers, T., Cooper, L., Cigrand, K., & Donn, L. (1990). A component analysis of functional communication training across three topographies of severe behavior problems. Journal of Applied Behavior Analysis, 23, 417-429.

Worsdell, A., Iwata, B., Hanley, G., Thompson, R., & Kahng, S. (2000). Effects of continuous and intermittent reinforcement for problem behavior during functional communication training. Journal of Applied Behavior Analysis, 33, 167-179.

Yoder, P. & Stone, W. L. (2006).A randomized comparison of the effect of two prelinguistic communication interventions on the acquisition of spoken communication in preschoolers with ASD.. Journal of Speech, Language, and Hearing Research, 49, 698-711

Author Contact Information

Robert H. LaRue, Ph.D., BCBA

Rutgers, The State University of New Jersey

Douglass Developmental Disabilities Center

151 Ryders Lane

New Brunswick, NJ 08901

Phone: (732)932-3017


Mary Jane Weiss, Ph.D., BCBA

Rutgers, The State University of New Jersey

Douglass Developmental Disabilities Center

151 Ryders Lane

New Brunswick, NJ 08901

Phone: (732)932-3017


Mary Kelly Cable, M. A., CCC-SLP

Rutgers, The State University of New Jersey

Douglass Developmental Disabilities Center

151 Ryders Lane

New Brunswick, NJ 08901

Phone: (732)932-3017
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Author:LaRue, Robert; Weiss, Mary Jane; Cable, Mary Kelly
Publication:The Journal of Speech-Language Pathology and Applied Behavior Analysis
Article Type:Report
Geographic Code:1USA
Date:Jun 22, 2009
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