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Augmentative and Alternative Communication Systems 

Augmentative and Alternative Communication Systems

Augmentative and Alternative Communication Systems

Marjorie H. Charlop

, Alissa L. Greenberg

, and Gina T. Chang

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Points of Interest

  • It is important to consider presentation format and stimulus duration when using AAC systems with persons with autism.

  • A visual-constant system (i.e., one in which the stimuli are visual and always present) may best complement the strengths of this population.

  • Research suggests that a variety of AAC systems can be effective in teaching communication to persons with autism.

  • However, the most effective AAC system for a specific child needs to be individually chosen.

  • When choosing an AAC system for an individual, practitioners should consult the literature as well as consider both individual and environmental characteristics.


Much attention has been placed on the development of communication in persons with autism. By definition, autism is a social communicative disorder, including qualitative impairments in both verbal and nonverbal communication (APA, 2000; Schreibman, 2005). Approximately one-third of persons diagnosed with an autism spectrum disorder (ASD) will not develop functional natural speech by adulthood (National Research Council, 2001). If speech does occur, onset is usually delayed and it is often characterized by abnormalities such as echolalia, idiosyncratic words or phrases, monotonous intonation, and an inability to sustain reciprocal conversation (Howlin, 2006; Kanner, 1943). Although communication interventions for children with autism have a long history of targeting verbal speech (Baer et al., 1968; Risley & Wolf, 1967), progress is often extremely slow and limited (Lovaas, 1977; Howlin, 1989). Poor outcomes have led interventionists to turn to other means, including augmentative and alternative communication (AAC) (Howlin, 2006).

Augmentative and Alternative Communication Systems

The American Speech-Language-Hearing Association defines augmentative and alternative communication (AAC) systems as “an integrated group of components, including the symbols, aids, strategies and techniques used by individuals to enhance communication. The system serves to supplement any gestural, spoken, and/or written communication abilities.” (ASHA, 1991, pp. 9–10.) Augmentative refers to the process of supplementing existing speech to increase communication, and alternative refers to the use of technology other than natural verbal speech to communicate (e.g., sign language, picture cards). Application of AAC has extended to people with sensory and motor deficits (e.g., individuals with visual and hearing impairments and cerebral palsy), intellectual and developmental disabilities (e.g., Down syndrome, Fragile X Syndrome, fetal alcohol syndrome, and autism), and physical disabilities (e.g., Amyotrophic Lateral Sclerosis) (Beukelman & Mirenda, 2005).

Autism and Augmentative and Alternative Communication Systems

AAC systems have been used to address the communicative deficits of persons with autism since the 1970s (Ogletree & Harn, 2001). Early applications focused on manual signs, tangible symbols, lexograms, and orthographic symbols. In the 1980s, the use of visual-spatial symbols gained popularity. More recently, advances in technology have led to an increase in the use of computer software programs and voice-output communication aids for persons with autism (Mirenda & Erickson, 2000).

In this chapter we will review the different AAC systems that have been used with persons with autism, along with the relevant research for each system. Although several different categorizations can be used when presenting AAC systems (e.g., aided versus unaided, input versus output), we have chosen to categorize AAC systems along two dimensions that are relevant for this population: presentation format and stimulus duration. This format, adapted from Charlop-Christy and Jones (2006), will guide our discussion of the potential benefits and limitations for using each type of AAC system with persons with autism.

Presentation Format

Since Kanner (1943) first described children with autism, it has been well-documented that although these children’s verbal skills are significantly impaired, their visual-spatial skills may be normal or even advanced (Hermellin, 1976). For example, many of these children perform quite well on embedded figures and block design tests (see Mitchell & Ropar, 2004 for a review of visual-spatial abilities in persons with autism).

This discrepancy between visual and verbal skills has been empirically validated by several studies. Lincoln, Courchesne, Kilman, Elmasian, and Allen (1988) assessed the intellectual functioning of 33 individuals with autism ranging in age from 8 to 29 years with the Wechsler Intelligence Scale for Children–Revised (WISC-R) (Wechsler, 1974) or the Wechsler Adult Intelligence Scale–Revised (WAIS-R) (Wechsler, 1981). Participants received the lowest scores on the Comprehension and Vocabulary subtests, which require the most verbal reasoning, and the highest scores on the Block Design and Object Assembly subtests, which require the most visual skills.

Other studies have found that when compared to typically developing controls, persons with autism show deficits in their verbal skills but not in their visual skills. Rumsey and Hamburger (1988) compared the performance of 10 men with infantile autism and average verbal and nonverbal intelligence, ages 18 to 39 years, with normal controls on a range of neuropsychological tests that measured language and visual-spatial abilities. Results indicated that although the men with autism did not perform differently from the controls on the visual-perceptual measures, they performed much worse than the controls on simple and complex verbal problem-solving tasks. A similar pattern of results was found in Ozonoff, Pennington, and Rogers’ (1991) comparison of 23 people with ASD, ranging in age from 8 to 20 years, with 23 controls matched for IQ, age, sex, and socioeconomic status.

These results have also been replicated in studies that focus on children with autism. In Williams, Goldstein, and Minshew (2006), 56 high-functioning children with autism were compared to 56 control children matched for age and IQ. The children with autism performed worse than the controls on the complex language tasks but not on the visual-spatial tasks.

Although the previous studies were conducted with high-functioning persons with autism, this cognitive profile is also found in low-functioning children with autism (Quill, 1997). In addition to demonstrating higher abilities on nonverbal problem-solving tasks than on verbal reasoning problems, low-functioning persons with autism also have severe receptive and expressive language impairments (Bristol et al., 1996). In fact, as the overall degree of mental retardation increases, so does the gap between verbal and nonverbal abilities (Quill, 1997).

If persons with autism have advanced visual skills, then visually based interventions should have high rates of success with this population. Quill and Grant (1996) found that language comprehension increased for four nonverbal children with autism when both oral and graphic instructions were presented simultaneously. For example, although the children did not initially respond to purely oral questions, such as “Which one is [attribute],” they were able to correctly respond when the verbal question was paired with a picture that depicted the attribute. Other successful visual interventions include video modeling (e.g. Chalrop-Christy et al., 2000; Sherer et al., 2001), cue cards (e.g., Charlop-Christy & Kelso, 2003), and photographic activity schedules (e.g., MacDuff et al., 1993). This research implies that visual AAC systems might be effective systems for persons with autism.

Stimulus Duration

The issue, however, is more complex than presentation format. Research indicates that stimulus duration is also an important consideration. In the studies previously mentioned (Lincoln et al., 1988; Ozonoff et al., 1991; Rumsey & Hamburger, 1988; Williams et al., 2006) the participants with autism performed best on the tasks in which the stimuli were visible for the entire duration of the task (e.g., form discrimination, matching, block design, object assembly, and pattern analysis). These results suggest that constant visual stimuli may be preferable to transient visual stimuli.

Research on attention and memory processes further support this conclusion. Children with autism demonstrate impairments in rapidly shifting attention (Courchesne et al., 1994) This suggests that children would have difficulty attending to, and therefore encoding, a series of rapidly spoken words or rapidly presented visual stimuli, such as gestures or pictures. Visually constant stimuli, on the other hand, would be easier to attend to, and children could attend to the stimuli until they were successfully encoded (Quill, 1997). Research on memory in persons with autism also supports the use of visually constant stimuli. Persons with autism perform better on cued-recall memory tasks than on free-recall memory tasks (Quill, 1997). Therefore, constant visual stimuli may enhance memory because they can serve as visible retrieval cues.

Presentation Format and Stimulus Duration Applied to Communication

When applied to communication, the two dimensions of presentation format and stimulus duration yield three different modalities of communication training. Communication training may be auditory-transient, visual-transient, or visual-constant (Charlop-Christy & Jones, 2006). In auditory-transient AAC systems, the stimuli are presented auditorily and do not persist in time. Once a word is spoken, the stimulus is gone. Clearly, there would not be an auditory-constant system. Visual-transient AAC systems present information visually for brief periods of time. For example, in sign language, the stimuli consist of body movements, which, once they are performed, are no longer available. In contrast, in visual-constant AAC systems, the stimuli are also visual, but they are always available. For example, a picture is a visual stimulus that, unless removed, is always available to the AAC user.

Table 64-1 depicts these modalities, along with providing AAC examples for each category. In the following sections, we will review each modality and the relevant AAC systems, referring back to their potential advantages or disadvantages for persons with autism given our previous discussion on presentation format and stimulus duration.

Table 64–1. Augmentative and alternative communication systems categorized by stimulus duration and presentation format

Presentation Format

Stimulus Duration





Speech; Computer-generated vocalization.


Sign-language; Gestures.





Picture Exchange

Communication System (PECS); Voice-output communication aids (VOCAs).


In the auditory-transient modality, stimuli are presented in the auditory modality and only last for brief periods of time. For example, in speech, the sounds of words do not persist over time. Therefore, a child with autism needs to “hear” speech, attend to it, remember it, and then figure out its meaning (Charlop-Christy & Jones, 2006). These steps may be difficult given the population’s difficulties with encoding verbal information and may partially explain why communication interventions that focus on verbal imitation have limited success (Charlop-Christy et al., 2008; Lovaas, 1977). Computer-generated vocalizations, unless paired with a visual stimulus, have the same limitations as speech.


In visual-transient communication, information is presented visually but it also does not persist through time (Charlop-Christy & Jones, 2006). Sign language is an example of a visual-transient AAC system. The body movements that are used in sign language are presented visually, but they do not last. Studies that report on the use of signs with persons with autism first appeared in the 1970s (e.g., Bonvillian & Nelson, 1976; Fulwiler & Fouts, 1976; Konstantareas et al., 1978). After we review this area of research we will return to the potential problems with using a visual-transient system with persons with autism.

Sign Language

Although initial sign-language programs were based on formal systems, such as American Sign Language (ASL), today abridged versions are often used with persons with autism. These versions may incorporate simpler hand movements or a modified vocabulary (Howlin, 2006). Initial studies with persons with autism compared the effects of presenting speech and sign language together on receptive vocabulary (Brady & Smouse, 1978; Carr & Dores, 1981; Carr et al., 1984), expressive vocabulary (Barrera et al., 1980; Barrera & Sulzer-Araroff, 1983; Layton, 1988; Yoder & Layton, 1988), or both expressive and receptive vocabulary (Layton, 1988). The results of these studies demonstrate that, for many participants, total communication training generates faster and more complete learning of vocabulary in comparison with speech alone conditions. These findings were especially robust for participants who demonstrated low verbal-imitation skills (Carr & Dores, 1981; Carr et al., 1984; Yoder & Layton, 1988). Although these findings seem to support the use of sign language for children with autism, almost all of these studies taught receptive or expressive labels in response to questions such as, “What is this?” or, “Show me the sign for [object label].” That is, the participants were not using sign language to communicate functionally in the natural environment. It is unclear if the participants in these studies would use sign language to request preferred items. Unfortunately, little research has examined the use of total communication to teach communication that is functional (i.e., can be used to spontaneously request a variety of items; Mirenda, 2003).

One study, conducted by Richman, Wacker, and Winborn (2001), compared the use of signing with a picture communication system in a functional communication training (FCT) program. A highly aggressive 3-year-old boy with pervasive developmental disorder (PDD) learned both to sign “please” and to exchange a generic picture for “please” when requesting preferred items. The child acquired both systems, and aggression decreased when reinforcers were presented for either exchanging a card or signing “please.” When reinforcement was provided concurrently for both systems, the child showed a preference for signing. From these results, researchers concluded that signing may have been more efficient (i.e., required less effort) for this particular child. Keep in mind, however, that this study had one participant and that heterogeneity and individual differences are common for this population. Also, the child in this study learned only one sign. Other studies, which target multiple signs, suggest that even after extensive training, students with autism are likely to acquire only a few functional signs (Layton & Watson, 1995). Clearly, more research based on the principles of best evidence is needed to empirically investigate the use of sign language as a means of teaching communication to persons with autism.

In the meantime, interventionists considering the use of sign language with persons with autism should evaluate certain characteristics of this AAC system. First, remember that sign language is a visual-transient modality (Charlop-Christy & Jones, 2006). Processing sign language requires both attention to the visual stimulus and an ability to hold the visual stimulus in one’s memory after the sign is no longer being displayed. The transient form of sign-based communication requires faster processing speed of visual stimuli than of visual stimuli that are constant (e.g., a picture) (Charlop-Christy & Jones, 2006). Furthermore, when generating communication, sign formation requires a two-stage recall memory process: (1) a search of one’s memory for potential signs, and (2) a discrimination process to decide which of the potential signs is correct (Light & Lindsay, 1991). In contrast, visually constant systems, which rely on recognition memory, do not require users to search their memory for the correct stimuli; the visuals are always present, thus lowering the processing demands placed on the system user (Mirenda, 2003).

In addition to the limitations of a visual-transient system, sign language has other features that may make it difficult for persons with autism. First, one of the prerequisites of symbolic communication, such as sign language, is the use of more basic communication forms, such as gestures (Miranda & Erickson, 2000). Persons with autism characteristically lack the use of complex gesturing to communicate (Schreibman, 2005). Many children with ASDs do not demonstrate gestures beyond taking a person by the arm to the item they want. Extensive training with basic gesturing (including proximal and distal pointing) would be required to develop an ability to understand the use of gestures prior to sign-language training (Miranda & Erickson, 2000).

Second, not everyone is familiar with sign language. Unless primary communicative partners, such as family members, are willing to learn sign language, the ability of nonverbal persons with ASDs to communicate is limited (Weitz et al., 1997; Wilkinson & Hennig, 2007). Furthermore, even if primary communicative partners do learn to sign, communication is still not completely functional because the user may be unable to communicate with unfamiliar persons (Mirenda & Erickson, 2000). The need for a translator for community outings thus makes independent living less likely.

Lastly, sign language requires that participants possess manual dexterity (Sundberg & Sundberg, 1990; Wraikat et al., 1991). Unfortunately, persons with ASDs often demonstrate difficulties with fine-motor actions, coordination, and gross-motor imitation, making the process of learning signs difficult (Seal & Bonvillian, 1997; National Research Council, 2001). As a result, persons with ASDs often develop idiosyncratic signs. Communication partners must not only know sign language, but they must also know how the specific person’s signs differ from standard signs (Wilkinson & Hennig, 2007).

The benefits of sign language should not be discounted before future research further explores the applications of this AAC system to persons with autism. Better methodology, larger sample sizes, and replications of present research are needed. Thus, much more exploration into the use of sign language is suggested before a conclusion about this AAC with children with ASDs can be reached.


Information in the visual-constant modality is presented visually and persists over time (Charlop-Christy & Jones, 2006). The majority of AAC systems fall under this category, including orthography, picture schedules, Aided Language Simulation (ALS), System for Augmenting Language (SAL), voice-output communication aids (VOCAs), and the Picture Exchange Communication System (PECS). As we review each AAC system, remember the benefits that the visual-constant modality may have for persons with autism. Because these visual stimuli persist over time, they accommodate the potential need for longer periods of processing time (Ogletree & Oren, 2006). Furthermore, visual-constant stimuli are easier to attend to, enhance encoding, and may serve as a memory aid during retrieval processes (Charlop-Christy & Jones, 2006).


Orthography refers to written stimuli. Research on orthography has focused on using the written word as an AAC input. That is, children are shown a word, and then taught to respond appropriately. In an early study, three nonverbal adolescents with autism were taught three words both expressively and receptively (La Vigna, 1977). In the expressive task, the participants were shown an object and taught to choose the corresponding word card. In the receptive task, the participants were shown the word card and taught to choose the corresponding object. It took the participants an average of 1,471 trials to master three words both expressively and receptively.

Given the slow rate of acquisition, orthography may be more appropriate for higher-functioning persons (Howlin, 2006). In fact, research findings indicate that written scripts can be used to teach complex social behaviors to children with autism in elementary and middle school. For example, Charlop-Christy and Kelso (2003) taught conversational skills to three children with autism, ages 8 to 10 years, who were verbal and literate. In this study, children successfully responded to a conversational question and asked a contextually appropriate question after just two to four presentations with the cue cards. After training, this skill was generalized across setting and conversation topic, in the absence of cue cards. Similarly, Krantz and McLannahan (1993) used written scripts to facilitate social initiations. During an art project, four children with autism were given a card with 10 single-line social initiations (e.g., “John, did you like to swing outside today?”). Initially, the children were physically prompted to read each script and then cross it off when finished. The scripts were then faded one word at a time. After training, the children’s initiations had increased to the same range as three of their typically developing peers.

These studies provide support for the use of orthography as an effective AAC input system for literate persons with autism. High-functioning persons with autism seem to be able to attend to the visually constant stimuli, encode them, and then respond appropriately. This AAC system would be especially useful for children who are hyperlexic, a specific condition which is found frequently among persons with autism (Ogletree & Oren, 2007). The main characteristic of hyperlexia is an above-average reading level paired with a below-average comprehension level for spoken language. Hyperlexic children are often able to learn to speak through extensive repetition and memorization. The condition is closely associated with autism, but there is some debate as to whether it is an autism spectrum disorder or a completely distinct disorder.

Research, however, has not been conducted on the use of orthography as an AAC output system, or as an alternative to verbal speech. That is, empirically controlled research is needed on the use of written material provided by the person with autism to communicate. Such AAC systems might consist of small laptops on which persons with autism can type messages, text messaging apparatuses such as cell phones, and writing.

Picture Schedules

Like orthography, picture schedules are also a visual-constant AAC input system. Picture schedules can be divided into within-task schedules and between-task schedules. In within-task schedules, children learn to follow pictures to complete an activity. For example, Bryan and Gast (2000) taught four children with autism, ages 7 to 8 years, to follow four pictures that sequenced an academic activity (e.g., file-folder games, worksheets). The participants learned to complete the activity using the picture schedule, and after training, the children were able to generalize the skill to a novel activity. Picture schedules can also be used for self-help skills. In Pierce and Schreibman (1994), three low-functioning children with autism, ages 6 to 9 years, were taught a variety of skills such as dressing, setting the table, and doing laundry. Each participant learned three sequences with a picture schedule, completed the sequences even when the therapist was not present, and generalized the skill across setting and task.

Picture schedules can also be used for between-task schedules. These programs help participants learn to transition from one activity to another. For example, MacDuff and colleagues (1993) taught four children, ages 9 to 14 years, to follow a picture activity schedule that included six different after-school activities (e.g., LEGOs, puzzle, TV, handwriting worksheet) and lasted for approximately 60 minutes. The participants were taught to follow their schedules through graduated guidance, which was faded until the teachers were no longer in close proximity to the participants. After training, which ranged from 13 to 27 sessions, the participants maintained the behavior, and generalized the skill to new sequences with the same photographs and to new sequences with different photographs. In a similar study with younger children, the parents of three children with autism, ages 6 to 8 years, learned to help their children follow picture schedules that depicted a variety of home-living tasks. In addition to acquiring the sequences, the children also displayed increases in social initiations and decreases in disruptive behavior, which were maintained for up to 10 months (Krantz, MacDuff, & McClannahan, 1993). These studies seem to indicate that picture schedules are extremely effective visual-constant AAC input systems. However, similar to orthography, picture schedules have not been used as AAC output systems for persons with autism. Although picture schedules may allow other people to communicate with persons with autism, they do not allow persons with autism to communicate with other people. This is an important distinction, because complete communication is bidirectional.

Aided Language Simulation

Aided Language Simulation (ALS) is a visual-constant AAC system that is used for both input and output. Goossens (1989) introduced ALS to teach individuals to both understand and use visual symbols as a means of communication. Through this system, as the communication partner talks to the ALS user, he or she also points to symbols on the user’s communication display. For example, the partner might point to the symbol for “ball” while saying, “I see ball.” Pairing the visual symbol with the spoken word may increase message saliency and assist in receptive and expressive understanding of vocabulary. In addition to AAC input, AAC output through ALS occurs when the user points to symbols on the communication display. In more advanced stages, the communicative partner responds contingently to the user by scaffolding more advanced communication and language (Goossens et al., 1992). For example, a child may point to a picture of a ball, and in response, the communicative partner would point to picture symbols for “big,” “red,” and “ball,” while saying, “Look, the big, red ball.” Although Harris and Reichle (2004) found that three children with moderate cognitive disabilities increased their symbol comprehension and production following ALS implementation, no studies have been published on the effectiveness of ALS with persons with autism.

System for Augmenting Language

The System for Augmenting Language (SAL) is very similar to ALS in that it also emphasizes augmenting both the input of the communication partner and the output of the AAC user. The main difference is that voice-output communication aids (VOCAs) are considered critical to SAL (Romski & Sevcik, 1992). In SAL, each learner’s VOCA has a display of visual-graphic symbols. Communication partners are instructed to use the symbols and VOCA to augment their speech input during naturally occurring communication opportunities. For example, at break time, the teacher would push the picture symbols for “Let’s play outside” and the VOCA would produce a digitized speech output. Learners are also encouraged to use the device throughout the day (Mirenda, 2001).

Research on the effectiveness of SAL with persons with autism is limited. However, Romski and Sevcik (1996) conducted a 2-year longitudinal study that examined the effectiveness of SAL with 13 students, ages 6 to 20 years, two of which had autism. All of the students were given a VOCA, and communication partners were taught to use the VOCAs, incorporating the components of SAL. At the end of 2 years, all of the participants learned to use SAL, with a total of 20 to 70 symbols mastered. Seven of the participants, including the two with autism, produced messages that consisted of combining two or more symbols. Five years later, all of the participants were still using their VOCAs with an average of 70 symbols (Romski et al., 1999). Although more research with persons with autism is needed, these studies suggest that SAL may be effective for both receptive and expressive communication skills.

Voice-Output Communication Aids (VOCAs)

As described earlier, voice-output communication aids (VOCAs) are electronic devices that produce digitized or synthetic verbal messages when the VOCA user presses a picture, line drawing, or other visual graphic symbol that is on the device board (Mirenda, 2001). In their recent review of VOCAs, Lancioni and colleagues (2007) found that between 1992 and 2006, 16 studies have been published on the use of VOCAs with persons with a range of developmental disabilities, including autism. Out of the 39 students in these studies, all but three succeeded to use VOCAs to varying degrees of success. For example, although some students only learned to use a single message for a single item, other students learned to use a variety of messages to request a range of preferred items (see Datillo & Camarata, 1991; Dyches, 1998; Schepis & Reid, 1995).

Only a few studies have specifically studied the effectiveness of VOCAs with persons with autism. Schepis, Reid, Behrman, and Sutton (1998) used naturalistic teaching strategies to teach four children with autism, ages 3 to 5 years, to use VOCAs during snack and play routines. Over a 1- to 3-month period, all four children demonstrated increases in their communicative interactions. In addition to using their VOCAs to request preferred items, the children also used the AAC system to respond “yes” and “no,” to make statements, and to make social comments (e.g., “thank you”).

More recently, Sigafoos, Didden, and O’Reilly (2003) taught children with autism or autistic-like characteristics, ages 3 to 13 years, to request objects using a VOCA. All three children were able to request, “I want more” to obtain access to a variety of preferred food, drink, and activity items. The children’s requesting behaviors were not affected by the presence or absence of digitized speech output, which was manipulated by the researchers. Furthermore, the digitized speech output did not cause any decreases in the children’s verbal speech. In fact, one child began to speak single words toward the end of the study.

Proponents of VOCAs argue that one of their strengths is that the verbal messages can be easily perceived by other people, including those who are unfamiliar with that particular AAC system (Lancioni et al., 2007). Durand (1999) tested this assumption in a study that taught five persons with severe disabilities, ages 3 to 15 years, to use VOCAs through functional communication training. All of the children engaged in severe problem behaviors, such as hand biting, screaming, crying, head banging, and aggressions toward others. With their VOCAs, they were taught to produce alternative communicative behaviors (e.g., “I need help,” “I want more”) that served the same function as their problem behaviors. After instruction at school, all of the participants were able to independently use their VOCAs in community settings with community members who had never been trained in VOCA use. In another study, however, Dyches, Davis, Lucido, and Young (2002) found contradicting results. Researchers taught an adolescent girl to make requests with a VOCA and with a simple pictographic display and assessed community members’ responses to requests made by these two AAC systems. Although the participant was able to generalize both systems to the community settings, community members took slightly longer to acknowledge requests produced by a VOCA as compared to requests made by nonelectronic picture displays. It is unclear if this difference resulted in a qualitatively different communication experience for the user or for the receiver of the communicative act, highlighting the need for more research on the effectiveness of VOCAs when used with untrained community members. Future research should investigate parents’ perceived barriers of the effectiveness of VOCAs, including factors such as difficulty with programming, inconsistent reliability, and difficulty using the device in a conversational manner (Bailey et al., 2006).

The Picture Exchange Communication System (PECS)

The Picture Exchange Communication System (PECS) is a visual-constant AAC system that targets communication through the exchange of graphic iconic symbols (Frost & Bondy, 1994). For example, instead of saying, “I want juice,” a child who uses PECS may bring a picture of juice to his mom. PECS was developed specifically for children with autism with limited or no functional verbal communication; however, its use has since expanded to include both children and adults with a range of developmental disabilities (Mirenda, 2001). PECS training is divided into six steps that mirror the development of communication and language in typical children (Bondy & Frost, 2001). The training protocol is discussed in detail in the PECS training manuals (Frost & Bondy, 1994, 2002) and is briefly outlined below.

  • Phase I: How to Communicate. The child learns how to exchange one picture for a desired item with the communication partner.

  • Phase II: Distance and Persistence. The child learns to travel to the communication book and to the communication partner.

  • Phase III: Discrimination Between Symbols. The child learns to discriminate between different picture symbols to find the picture symbol of the current preferred item.

  • Phase IV: Using Phrases. The child learns to combine picture cards to make phrases. For example, the child who wants juice will combine the “I want” picture card with the picture of juice on the sentence strip and exchange the sentence strip with the communication partner.

  • Phase V: Answering a Direct Question. The child learns to answer questions, such as, “What do you want?”

  • Phase VI: Commenting. The child learns to comment by combining the “I see” and “I hear” picture cards with other picture symbols. The child also learns to answer other questions, such as “What do you see?”

In addition to relying on a visual-constant modality, PECS training incorporates three other aspects that contribute to its success as a communication intervention for persons with autism. First, PECS is unique in its application of behavioral principles to an AAC intervention that emphasizes functional communication. The developers of PECS view functional communication as “behavior (defined in form by the community) directed to another person who in turn provides related direct or social rewards.” (Bondy, 2001, p. 127.) Therefore, there is a link between the communicative act (exchanging a picture of juice) and the child’s desire (thirst for juice). By teaching mands (requests) before tacts (comments), the child learns that communication is meaningful because it results in the acquisition of a desired item (Charlop-Christy & Jones, 2006). An emphasis on functional communication that is both meaningful and motivating increases the likelihood that the communicative behavior will occur again (Skinner, 1975).

Second, in addition to emphasizing functional communication, PECS training increases the likelihood that communication will be spontaneous. Unlike other communication interventions that begin training with a verbal prompt (e.g., “Point to what you want”), no verbal prompts are used in PECS training. Instead, a second trainer physically prompts the child from behind. The physical prompter does not socially interact with the child, and only prompts the child to exchange the picture card once he or she indicates a desire for the item (Bondy & Frost, 2001). The physical prompt can be quickly faded through a time delay procedure (e.g. Charlop & Trasowech, 1991). This procedure decreases the likelihood of prompt dependence and ensures that the communicative behavior is child-initiated (Charlop-Christy & Jones, 2006).

Third, PECS recognizes that communication is a social behavior. In typically developing children, communication involves much more than verbal language (Koegel, 2000). In fact, before they learn to speak, typically developing children learn to communicate with their caregivers through other behaviors such as looking, approaching, or pointing (Bondy & Frost, 2001). It is important to recognize the social nature of communication, because social deficits are one of the core features of children with autism (Kanner, 1943). Research indicates that children with autism are either delayed in or lack the social skills (e.g., imitations skills, simple gesturing, social responsiveness, and joint attention) that have been established as critical prerequisites for verbal speech development (Happe, 1994; Koegel, 2000; Schreibmen, 2005). PECS addresses these deficits by ensuring that children with autism learn the basic social elements of communication (e.g., approaching a communication partner and gaining his or her attention) before they learn to discriminate between different pictures (Frost & Bondy, 1994), increasing their likelihood of becoming successful communicators in a social world.

PECS Research

PECS is one of the most widely researched AAC interventions for persons with autism. We will present this literature by dividing it into four main topic areas: (1) PECS acquisition, (2) PECS generalization and maintenance, (3) ancillary benefits of PECS training, and (4) comparison studies. The majority of PECS research focuses on PECS acquisition in the training environment. In their review of PECS and VOCA usage with persons with developmental disabilities, Lancioni and colleagues (2007) found that between 1992 and 2006 17 studies have been published on PECS. In these studies, out of a total of 173 participants, only three participants failed to acquire PECS and a fourth participant ended training because of illness. These findings seem promising; however, the authors note that one must be cautious when interpreting PECS success. Although some of the studies only required participants to exchange one picture for a preferred item (e.g., Sigafoos et al., 1996), other studies required participants to learn PECS through Phase V (e.g., Charlop-Christy et al., 2002). A person who has learned to exchange one picture for one preferred item would not seem to have acquired functional communication as defined by Bondy (2001).

A smaller number of studies have taught PECS to persons with autism according to the guidelines in the PECS manual (Frost & Bondy, 1994, 2002). These studies also indicate that, when taught correctly, persons with autism will successfully acquire PECS through Phase III or higher (see the following for studies that present acquisition data: Charlop-Christy et al., 2002; Ganz & Simpson, 2004; Kravits et al., 2002; Magiati & Howlin, 2003; Tincani et al., 2006). As characteristic of most skills, duration of PECS training varies for each child. For example, although the three children in Charlop-Christy and colleagues (2002) reached criterion in Phase V after an average of 246 trials, the three children in Ganz and Simpson (2004) reached criterion in Phase IV after an average of 346 trials. In a third study, after 6 months of PECS training in the classroom, the average PECS level for 34 children with autism was between Phases IV and V (Magiati & Howlin, 2003). In conclusion, the research demonstrates that children with autism can easily acquire PECS in the training environment through Phase III or higher.

Fewer PECS studies have included generalization and maintenance measurements. Some of the most rigorous generalization data comes from a study that taught PECS to adults with developmental disabilities (Stoner et al., 2006). In this study, the three adults who learned to use PECS through Phase IV at home also generalized PECS use to fast food restaurants in the community. Studies limited to persons with autism also indicated that participants can generalize PECS use across people (Tincani et al., 2006), across stimuli (Marckel et al., 2006), and across activities (Schwartz et al., 1998). However, more rigorous assessments are needed before we can conclude that persons with autism generalize PECS use outside of the training environment to all naturally occurring settings and situations and with a variety of people. Current research in our lab is assessing children’s generalization of PECS use across environments, situations, and people. Initial results indicate that four children with autism who were taught PECS in a workroom generalized spontaneous PECS use to a playroom with a therapist, to their homes with a parent, and to the community with a stranger. One child required minimal training in one of the generalization settings, and the other children did not require any additional training for generalization to occur in all three settings (Greenberg et al., 2010). Furthermore, only one study has included follow-up data on participants’ PECS use (Howlin et al., 2007). In this study, classrooms of children with autism were randomly assigned to an immediate treatment group, delayed treatment group, or control group. Treatment consisted of a 2-day PECS workshop for teachers, six half-day school-based training sessions, and 5 months of consultation with a PECS expert. Although both treatment groups showed increases in PECS use immediately after treatment, the children in the immediate treatment group did not maintain these gains 10 months after the consultation had ended. Clearly, more data is needed on PECS maintenance, especially when treatment occurs in 1:1 sessions.

The third area of PECS research presents findings on the ancillary benefits of PECS training. These studies have found that increases in communication with PECS are related to other positive outcomes (Charlop-Christy et al., 2002; Frea et al., 2001; Anderson et al., 2007). After PECS training, the three children in Charlop-Christy and colleagues (2002) showed increases in social behaviors such as eye contact, joint attention, play, requesting, and initiations and decreases in problem behaviors including tantrums, grabbing, out-of-seat behaviors, and disruptions. In another study, a 6-year-old child who learned PECS spent more time playing and less time watching TV (Anderson et al., 2007). Lastly, Frea et al. (2001) demonstrated that once a child learned to communicate effectively with PECS, aggressions toward others decreased. This research demonstrates the importance of functional communication. Once children learn how to use PECS, this form of communication may replace other more maladaptive forms of communication, such as tantrums or aggressions. Furthermore, PECS training reinforces social behaviors such as approaching other people and exchanging pictures with them. These interactions seem to teach PECS users that social interactions can be reinforcing, setting them on the path of becoming social initiators—an important achievement for persons with autism.

The most widely studied ancillary benefit of PECS training concerns concomitant changes in the participants’ verbal speech (Anderson et al., 2007; Chalrop-Christy et al., 2002; Carr & Felce, 2007; Ganz & Simpson, 2004; Howlin et al., 2007; Kravits et al., 2002; Liddle, 2001; Magiati & Howlin, 2003; Schwartz et al., 1998; Tincani et al., 2006). Many of these studies report positive results. The three children in Charlop-Christy and colleagues (2002) showed increases in both their imitative and spontaneous speech during free-play and academic sessions. Furthermore, two of the three participants increased their mean-length utterances during and after PECS training. In another single-subject study, PECS training was related to an increase in the number of intelligible words spoken by three children with autism during their PECS training sessions (Ganz & Simpson, 2004). Lastly, although not experimental, Schwartz and colleagues (1998) found that when PECS had been implemented in the classroom for 1 year, 44% of the students showed marked increases in their spoken language.

Although most of the studies indicate that PECS leads to increases in children’s verbal speech, some studies have not found such results. In Howlin and colleagues’ (2007) randomized group design, PECS training was not related to increases in the frequency of speech or improvements on language test scores for the children in the two treatment groups. Likewise, although Carr and Felce (2007) report that PECS training led to an increase in communicative initiations during classroom observations, this increase was almost entirely accounted for by an increase in the participants’ PECS use, not verbal speech. Mixed results indicate the need for more research on the effects of PECS training on learners’ verbal speech. Particular attention should be paid to initial differences in the speech profiles between those persons who acquire verbal speech and those who do not. Furthermore, researchers must explicitly describe the sessions in which speech was measured—differences in speech may emerge between PECS training sessions and free-play observations and between sessions in which the PECS book is available or not.

The final area of PECS research compares PECS with other AAC systems such as sign language and VOCAs. Although researchers are now attempting to determine which is the best AAC system for persons with autism, contradictory results indicate that the answer may not be a simple one. Studies comparing PECS and sign language report outcomes such as rate of acquisition, generalization, and the participants’ preferred system. Several studies support the use of PECS. For example, Chambers and Rehfeldt (2003) taught four mands to four adults with mental retardation, ages 19 to 40 years, with both sign language and PECS using an alternating-treatments design. Three of the four participants required fewer training sessions to acquire the four mands using PECS than using sign language. The fourth participant did not reach criterion in either modality. Three participants generalized PECS use across settings, and two of the participants generalized sign use across settings. When the items were out of view, all four participants were more likely to request them using PECS than using sign language. Adkins and Axelrod (2002) taught a 7-year-old boy with PDD to request a variety of items with PECS and American Sign Language (ASL). They report that the PECS acquisition rate was faster than the ASL acquisition rate (an average of 7.1 trials for PECS versus an average of 15.7 trials for ASL). These results were consistent even when the same word was taught under both systems. Furthermore, the child was more likely to generalize PECS use outside of training sessions than to generalize ASL.

Results from Tincani (2004) are not so clear-cut. In this study, two children with autism spectrum disorders, ages 5 and 6 years, learned to request items with PECS and sign language in an alternating-treatments design. One participant demonstrated a high percentage of independent mands with sign language after the training was modified to remove modeling prompts. The other participant demonstrated a higher percentage of independent mands with PECS. Both participants were more likely to emit word vocalizations during the sign language sessions. However, once the PECS protocol was modified to include a 4-second delay, the second participant’s word vocalization increased to an average of 90% of sessions.

Clearly, these studies do not indicate a clear preference for one AAC system over the other. Some researchers conclude that a student’s motor imitation skills should be considered prior to training (Tincani, 2004). This relates to response effort (Richman et al., 2001). If a child has severe fine motor delays, sign language might be less efficient than PECS. It would also be useful to compare the participants’ memory skills prior to training. Whereas sign language requires recall memory, the visual symbols in PECS provide constant reminders, and allow the participants to use recognition memory (Mirenda, 2003). Although visual-constant systems might be better adapted to the memory deficits in persons with autism (Charlop-Christy & Jones, 2006), this might not be an issue for persons with high recall memory. Typical of children with autism, there are individual differences that need to be taken into account before determining which AAC system should be used. The treatment of autism has never been “one-size-fits-all.”

Other studies have compared the use of PECS and VOCAs. Again, the results are mixed. Although PECS and VOCAs are both visual-constant systems, VOCAs differ in the addition of digitized or synthesized voice output (Lancioni et al., 2007). In their review of PECS and VOCAs, Lancioni and colleagues (2007) describe four studies that compare the use of these two AAC systems (see Bock et al., 2005; Dyches et al., 2002; Son et al., 2006; Soto et al., 1993). Two of these studies compared picture boards (instead of PECS) and VOCAs with adults with mental retardation. Whereas the participant in Soto and colleagues (1993) preferred the VOCA, the participant in Dyches and colleagues (2002) preferred the picture board.

Bock and colleagues (2005) taught six nonverbal boys diagnosed with developmental delay, all age 4 years, to request items using PECS and VOCAs in a pull-out room at their schools. Three of the children acquired requesting skills faster with PECS than with their VOCAs. The other three children did not demonstrate differences in acquisition rate between AAC systems. After training, generalization of both systems was assessed in each child’s main classroom. During these sessions, both systems were available to the children. Generalization results were mixed; three of the children demonstrated a clear preference for PECS, two of the children demonstrated a clear preference for VOCA, and one child did not show a clear preference for either system.

Only one published study has compared these two AAC systems with children with autism (Son et al., 2006). Three children, ages 3 to 5 years, were taught to request two snack items with both PECS and VOCAs. Acquisition rates did not differ for either system. After training, both systems were available to the children for the preference assessment sessions. One child showed a clear preference for her VOCA, and she chose it in 94% of opportunities. The other two children showed a clear preference for PECS, choosing it in 72% and 98% of opportunities.

As Lancioni and colleagues (2007) note, these studies do not indicate that one AAC system is better than another. Persons with autism are able to acquire both PECS and VOCA when making requests (Son et al., 2006).


Although research on children with autism and AAC systems has made substantial progress since AAC systems were first introduced with this population, the literature has areas of contradiction. It is not yet clear which AAC system is best for the majority of children with autism. However, this does not mean that science cannot inform our decisions. Interventionists should consult the literature to decide which AAC system would be best for each child on an individual basis. This process should involve a thorough consideration of many different factors including the child’s strengths and limitations, certain family variables, and other environmental constraints. When evaluating the specific child, important considerations would include the child’s communication needs, the child’s visual and auditory skill levels, the child’s motor abilities, and the child’s social skills mastery level. For example, if the child has strong visual discrimination skills and poor fine motor skills, PECS might be a better choice than sign language. If the child can make more complex statements via pictorial representations, then VOCAs might be the best choice.

Interventionists must also recognize that children do not develop in isolation. Children develop in complex environments, which will affect their communication in significant ways. Therefore, environmental variables must also be considered when choosing an AAC system for a specific child (Mirenda, 2003). Several of the most influential environmental variables might stem from the child’s parents or primary caregivers. Children’s parents are often their primary communicative partners. If an AAC system is going to be successful for the child, then its implementation must also be both supported by and feasible for the parents. In fact, AAC systems are most effective when AAC decisions are family-centered (Bailey et al., 2006). In addition to the child’s parents, broader contextual variables should also be considered. Interviews with adult AAC users and their family members identified environmental factors as having the potential to both contribute to and impede AAC effectiveness (Lund & Light, 2007). A significant consideration would be community members’ familiarity with different AAC systems. For example, if community members do not know sign language, then PECS or VOCAs might be more effective. Funding might also be of importance. If service providers will not fund more expensive AAC systems, families might not be able to afford VOCAs. Lastly, the educational system’s preferences should be factored into the picture. If teachers in a particular school encourage their students to communicate through sign language, they might not support the use of PECS for one child.

In conclusion, AAC decisions for children with autism must be made on an individual basis. Ideally, AAC use will result in functional, spontaneous communication across a variety of settings and with a variety of people (Mirenda, 2003). This goal will only be met if child, family, and environmental characteristics are all taken into consideration. Additionally, researchers should continue to explore the use of AAC systems with children with autism to better inform AAC decisions.

Challenges and Future Directions

The predominant theme throughout this chapter, and in other areas of autism work, is the need for more research. Since AAC systems were first introduced with persons with autism, we have learned a lot about their applications and potential benefits. However, there is still much more to know as most of the literature has been done with non-ASD populations. We end by highlighting three central questions to be addressed by future research.

  1. 1. Which AAC system is best for persons with autism?

As previously discussed, there is much work to be done in determining the best AAC system for persons with autism. Comparison studies will make important contributions to this field. However, it is essential that these studies follow evidence-based research practices. Most importantly, studies must demonstrate experimental control (Cooper et al., 2007). In comparison studies, experimental control is established when the researchers demonstrate that changes in the participants’ communicative behaviors are attributed to the AAC interventions, and not to any other confounding variable. When studying persons with autism, the best experimental method is often single-subject design (Cooper et al., 2007; Simpson, 2003). Single-subject design accounts for the heterogeneity of the population, highlighting variability within the data and between participants (Simpson, 2003). In addition to adhering to empirically validated research practices, researchers must also ensure that they are targeting socially significant behaviors (Cooper et al., 2007). This is especially important when studying AAC systems. Studies that target one request have not demonstrated that the AAC system leads to effective communication. Lastly, more comparison studies should include generalization and maintenance measurements (Schlosser & Lee, 2000). Studies that only compare acquisition rates between two AAC systems will not be able to conclude that one AAC system is more effective than the second AAC system. Truly functional communicative behaviors will be used across environments and maintained over time. Therefore, the most useful comparison studies will also highlight which AAC systems that lead to superior generalization and maintenance over other AAC systems.

  1. 2. What is the relationship between AAC use and the development of verbal speech?

Although AAC systems should provide persons with autism with a means of communication that is just as effective as verbal speech, many people still view verbal speech as an important milestone for persons with autism. Verbal speech is used by interventionists and researchers to distinguish high-functioning from low-functioning persons with autism (Charlop-Christy, 1987; Schreibman, 2005). Furthermore, many parents are often hesitant to implement AAC systems, fearing that their use will decrease the chances of their children ever speaking (Millar et al., 2006). In their review of the impact of AAC systems on speech production in individuals with autism, Schlosser and Wendt (2008) conclude that AAC systems frequently lead to modest gains in speech production, but that more empirical research is needed to investigate this area. Although more empirical research is needed to confirm that AAC use leads to increases in verbal speech, parents and interventionists should no longer be concerned that AAC use will lead to a decrease in children’s verbal speech or prohibit children from ever acquiring verbal speech.

  1. 3. Do AAC systems lead to functional communication?

Functional communication is achieved when children spontaneously use the skill in naturally occurring settings and situations (Horner & Budd, 1985). Functional communication should be our goal with AAC systems, as it is the only mark of successful communication. If AAC systems are functional, then children will use them to communicate effectively in their everyday lives (Mirenda, 2003). Unfortunately, research to date does not demonstrate that this goal has been met.

Embedded in this definition are two components: (1) communication must be spontaneous, and (2) communication must generalize. These two aspects are often difficult for persons with autism (Koegel, 2000; Lovaas et al., 1973; Lovaas et al., 1974; Schreibman, 2005). Koegel (2000) notes that although children can easily acquire AAC systems, they may have difficulties with generalization and require prompts in untrained situations. Although several studies have empirically investigated the generalization of AAC systems with persons with autism (e.g., Adkins & Axelrod, 2002; Marckel et al., 2006; Schwartz et al., 1998; Tincani et al., 2006), they have only measured AAC use in a limited number of settings and with a restricted number of people and items; these studies do not give us the complete picture of children’s AAC use outside of training and research situations.

Two different lines of research could address these limitations. First, AAC studies should include generalization measurements that attempt to reflect a variety of naturally occurring settings and situations. This implies that generalization probes should be conducted across settings, people, items, and situations. Second, other studies must look beyond these generalization measurements. Although important, generalization probes will not be able to capture all of the situations in which you would expect communication. Furthermore, behavior during research sessions does not always reflect behavior in real-world contexts (Charlop-Christy et al., 2008). Situations are often contrived and the presence of the researcher may influence both the child’s and the communication partner’s behavior. A generalization probe might indicate that a child frequently uses PECS at home with a parent during 10-minute sessions observed by the researcher, whereas the child might not use PECS as frequently in these real-world contexts during other times when the researcher is not present.

Autism researchers could benefit from looking at research trends outside of our field. Recently, AAC as a discipline has begun to stress the importance of including other outcome measurements. Lund and Light (2006) argue that determining the effectiveness of AAC involves more than looking at how frequently it is being used. If AAC is functional, it will impact the individual’s overall communication and functioning. These researchers stress the importance of looking at long-term outcomes across a range of domains, including receptive language, reading comprehension, communicative interaction, functional communication, educational and vocational achievement, self-determination, and quality of life. One way of approaching this issue involves interviewing parents of children who use AAC (Marshall & Goldbart, 2008). One of the major roadblocks to effective AAC use may be difficulty with implementation. AAC use can be expensive for families (especially when buying electronic devices, such as VOCAs), time consuming, and stressful (Lund & Light, 2007). If AAC is not feasible for the parents to implement, then it is unlikely to become functional for the child.

Research on the functionality of AAC systems reminds us of our goal. AAC systems should provide persons with autism with a means of communication—communication that is not prompt-dependent and context dependent, but rather communication that is spontaneous and effective in all situations and settings. This is a lofty goal. However, if achieved, it has the potential of dramatically improving the lives of many persons with autism. It is our hope that these benefits will continue to motivate researchers to study the applications of AAC systems with persons with autism.

Suggested Readings

Lancioni, G. E., O’Reilly, M. F., Cuvo, A. J., Singh, N. N., Sigafoos, J., & Didden, R. (2007). PECS and VOCAs to enable students with developmental disabilities to make requests: An overview of the literature. Research in Developmental Disabilities, 28, 468–488.

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

Schlosser, R. W., & Wendt, O. (2008). Effects of augmentative and alternative communication intervention on speech production in children with autism: A systematic review. American Journal of Speech-Language Pathology, 17, 212–230.


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