Facilitating Vocabulary in Toddlers Using AAC

Abstract

Toddlers benefiting from augmentative and alternative communication (AAC) often demonstrate delayed expressive vocabulary. However, a paucity of AAC intervention research exists for children under the age of 3. There have also been few AAC studies comparing language intervention techniques across children of any age. This study investigated two intervention techniques on the expressive vocabulary of three toddlers who were beginning AAC users. In one condition (focused stimulation), the speech-language pathologist (SLP) verbally modeled each target word 10 times during an intervention session. In the other condition (augmented input), the SLP modeled each target word 10 times during an intervention session by simultaneously speaking the word and using the child’s AAC system. The results revealed the participants’ expressive vocabulary improved during both conditions and was sustained and generalized for two of the three toddlers. The study provides preliminary, empirically based guidelines to consider during communication intervention with toddlers who are learning to use AAC.

Keywords

augmentative and alternative communication (AAC)age birth to 3 years treatment for communication disorders language/linguistics delays/disorders single-subject research methodology

Toddlers between the ages of 1 and 3 years with developmental disabilities typically experience significant difficulties communicating with others and developing receptive and expressive language due to their physical, cognitive, or sensory impairments. These children often rely on non-conventional means of communication and challenging behaviors to express basic wants and needs. These unconventional behaviors frequently interfere with social interaction and participation in activities that are considered facilitative for the child’s development. The timely provision of a communication system and suitable communication intervention is of paramount importance to facilitate development of appropriate behaviors and inclusion in social interactions and developmentally appropriate activities (Beukelman & Mirenda, 2013). In recent years, augmentative and alternative communication (AAC) has emerged as a promising clinical and educational strategy to help these children communicate and participate in the social and academic environments of their typically developing peers. Yet the mere provision of an AAC system does not by itself support language development. A range of language intervention approaches is needed to enhance the linguistic skills of toddlers who are beginning users of AAC (Branson & Demchak, 2009).

Training teachers and caregivers of toddlers with disabilities to recognize the children’s communicative attempts and to increase their responsive talk to these attempts is at the basis of responsivity education, a language intervention approach with a large base of empirical evidence. An example of a responsivity education program is It Takes Two to Talk—The Hanen Program for Parents (Manolson, 1992). Teachers and caregivers are taught three clusters of responsive interaction strategies to use in natural environments consisting of (a) child-oriented behaviors including waiting and listening, following the child’s lead, joining in and playing, and being face to face; (b) interaction promoting strategies consisting of asking a variety of questions, encouraging turn-taking, and matching turns to the child’s turn; and (c) language modeling strategies including imitating, labeling, expanding, and extending the child’s productions. This program has been found effective with late-talking toddlers and preschoolers with specific language impairment, as well as preschoolers with cognitive and developmental delays, and toddlers with cerebral palsy (Girolametto, 1988; Girolametto, Pearce, & Weitzman, 1996a, 1996b; Girolametto, Weitzman, & Clements-Baartman, 1998; Pennington, Thomson, James, Martin, & McNally, 2009; Tannock, Girolametto, & Siegal, 1992).

Focused stimulation is another language intervention approach used to facilitate language production in children with significant language delays. During an intervention session with focused stimulation, specific target vocabulary and grammatical markers are identified and modeled a minimum of 10 times to facilitate production (Fey, Cleave, Long, & Hughes, 1993). Focused stimulation (Cleave & Fey, 1997; Fey, Cleave, & Long, 1997; Fey et al., 1993; Robertson & Ellis Weismer, 1999), as well as focused stimulation combined with responsivity education (Girolametto et al., 1996a, 1996b; Girolametto et al., 1998), has been found to be effective for facilitating language production in young children with language impairments. While these approaches have been studied with children demonstrating language delays, developmental delays, and Trisomy 21, they have not been explicitly studied with children who are learning to use AAC, other than to examine parent–child pragmatic interactions (Pennington et al., 2009) and the acquisition of grammatical morphemes (Binger, Maguire-Marshall, & Kent-Walsh, 2011).

Augmented input is a language intervention approach specific to children who benefit from AAC. In this approach, the interventionist models the use of the child’s AAC system (e.g., by pointing to the graphic symbol on the child’s AAC system, or signing) while simultaneously speaking the target words (Goossens’, 1989). Augmented input has been found to be effective for improving single word vocabulary of preschoolers with moderate cognitive delays during structured activities (Harris & Reichle, 2004), developing the early syntax of children during camp activities (Bruno & Trembath, 2006), producing two-word combinations with preschoolers during play scenarios (Binger & Light, 2007), producing grammatical morphemes with school-aged children (Binger et al., 2011), and improving vocabulary comprehension during school activities (Dada & Alant, 2009).

Augmented input with the addition of responsivity education has also been found to be an effective intervention technique with children who use AAC. Caregivers are taught to use responsivity education techniques such as asking open-ended questions while modeling the use of the child’s AAC system, waiting expectantly for the child to respond, and recasting language produced by the child using the child’s AAC system (Rosa-Lugo & Kent-Walsh, 2008). The approach has been used during story book reading activities to increase communicative turn-taking between kindergartners and their parents and to increase multi-word productions in preschoolers and school-aged children (Binger, Kent-Walsh, Berens, Del Campo, & Rivery, 2008; Kent-Walsh, Binger, & Hasham, 2010; Rosa-Lugo & Kent-Walsh, 2008). This technique has also been implemented to increase early word production in toddlers with limited vocabularies during a variety of naturalistic activities (Romski et al., 2010).

Purpose of the Study

A paucity of AAC intervention research exists for children under the age of 3. Branson and Demchak (2009) completed a systematic review on the use of AAC with infants and toddlers with various disabilities. Although only seven studies provide conclusive evidence, it appears that a variety of AAC methods can be used successfully with children under age 3, including unaided methods (DiCarlo, Stricklin, & Banajee, 2001), non-electric aided methods such as the Picture Exchange Communication System (Anderson, 2001), and voice output communication aids (Iacono & Duncum, 1995). None of the reviewed studies compared language intervention approaches.

There have also been very few AAC studies comparing the effectiveness of different language intervention techniques across children of any age. Schlosser and Sigafoos (2006) conducted a systematic review of comparative AAC intervention studies using single-subject experimental designs. Only two studies were reported to compare different intervention techniques for teaching language during structured activities (Iacono, Mirenda, & Beukelman, 1993; Remington & Clark, 1983). More recently, Romski and her colleagues (2010) compared three conditions for improving vocabulary production in toddlers who used voice output communication aids: caregivers using speech only, caregivers modeling the use of the communication aid (augmented input), and caregivers prompting the toddlers to use their communication aid (augmented output). The target vocabulary was not in the participants’ original receptive or expressive vocabulary. Results indicated augmented input and augmented output resulted in significantly improved vocabulary production as compared with the spoken language condition.

Given the increasing use of AAC with young children, further research is needed to compare the efficacy of different language intervention approaches. The purpose of this preliminary study was to investigate the efficacy of two language intervention techniques, focused stimulation and augmented input, in increasing the expressive vocabulary of toddlers who are beginning users of AAC. Specifically, the study explored the following major questions:

Would the intervention techniques result in improved expressive vocabulary in comparison with a no treatment condition?

Would differences with respect to rate of acquisition be observed between the two intervention techniques? and

Would differences with respect to acquisition, generalization, and maintenance be observed between the two intervention techniques?

Method

Participants

Three children from Northern California who were learning to use AAC served as participants. Parents provided informed consent before the investigation began. All participants met the following selection criteria: (a) They were between 2 and 3 years of age; (b) they presented with severe communication difficulties and speech that was less than 10% intelligible as reported by their speech-language pathologist; (c) they communicated via multi-modal AAC consisting of a combination of unaided means such as facial expressions, gesturing and pointing, manual signs, word approximations, limited word production; and/or low tech aids such as visual grids, communication boards, and flip charts; (d) they had an expressive vocabulary of 50 or fewer words; (e) they demonstrated moderate, mild, or no cognitive delays as reported by their speech-language pathologist and special education teacher; (f) they demonstrated hearing and vision within normal limits, with or without correction; and (g) they were from monolingual English speaking families. Two participants were Caucasian and one participant was Asian American. All were from middle class or upper middle class socio-economic backgrounds. All participants attended center based early intervention programs and received individual speech and occupational therapy. Appendix A describes participant demographics.

Karl

Karl was diagnosed with extreme prematurity resulting in multi-system dysfunction and was hospitalized for 6 months following birth. He had a history of several strokes, relied on a nasal oxygen tube for respiration, was dependent on a gastrostomy tube for nutrition, and demonstrated left vocal fold paralysis. He had a limited sound repertoire consisting of the vowels /ah/ and /ih/, and /oo/ and the consonants /b/ and /m/. Volume was soft and vocal quality was strident and hoarse. Karl demonstrated age appropriate receptive language skills whereas his expressive language skills were mildly delayed. He used unaided facial expressions, pointing and gesturing, 50 manual signs, word approximations, and less than 5 intelligible words to communicate. Karl’s aided communication system consisted of photos and line drawings on a visual grid containing 10 symbols. He primarily communicated through a combination of manual signs and pointing to graphic symbols. Prompting was required for production of speech.

Carol

Carol was diagnosed with developmental delays in speech and language and associated ataxic gross motor characteristics of unknown etiology. Speech production consisted of the consonants /w/, /h/, /m/, /p/, /b/, /d/, /n/, and /y/ with omission of final consonants, and a variety of vowels that were often distorted. Her receptive language skills were age appropriate whereas her expressive language skills were mildly delayed. Expressively, she used facial expressions, pointing and gesturing, manually signed 50 words, and produced approximately 40 word approximations and words to communicate. Her aided communication consisted of photos and line drawings on a visual grid of 10 items. Carol primarily communicated through a combination of pointing and gesturing, manual signs, and natural speech.

Mick

Mick was diagnosed with developmental delays across all domains of unknown etiology. Minor dysmorphic features were present at birth including webbing between two toes and microcephaly. Mick wore corrective lenses and was more verbal than Karl or Carol with speech production consisting of the consonants /h/, /w/, /p/, /b/, /m/, and /g/ and a variety of vowels. His receptive language and cognitive skills were moderately delayed whereas his expressive language skills were severely delayed in all modalities. Mick communicated through a combination of facial expressions, pointing and gesturing, manually signed the word “more,” pointing to graphic symbols and word approximations. He had a communication book containing multiple pages of 18 photos and line drawings per page organized by semantic categories but only used it under heavy prompting conditions. Mick’s aided AAC system was simplified during the intervention phase of the study to a single page communication board consisting of 12 line drawings. Although he initially vocalized more than Karl or Carol, he demonstrated more difficulty imitating vocalizations and signs in comparison to Karl and Carol and did not produce two- or three-word combinations.

Interventionists

Four adults also participated in the study. Two speech-language pathologists (SLPs) served as interventionists and completed baseline, intervention, and maintenance probes with the participants. Both SLPs met the following inclusion criteria: (a) They were state licensed and American Speech-Language-Hearing Association certified SLPs, (b) they had a minimum of 5 years experience working with toddlers with severe communication difficulties who received AAC services, and (c) they provided individual speech and language therapy to the toddlers participating in the study. One SLP worked with Karl and Carol and the other worked with Mick. Two additional adults, a special education teacher and an SLP, completed generalization probes with the participants. The special education teacher provided home services to Karl and taught a group program with Carol. She was a state credentialed early childhood special education teacher and had 2 years experience working with toddlers with severe communication difficulties who received AAC services. She completed generalization probes with both toddlers. The other SLP taught Mick in a group program but did not work with him individually. She met the same inclusion criteria as the treating SLPs above and completed generalization probes with Mick.

Settings

The same settings were used for baseline, intervention, generalization, and maintenance sessions at an early intervention center and home for Karl, the same early intervention center for Carol, and a different private speech agency for Mick. Sessions were completed once to twice weekly; Karl was hospitalized for several weeks during the intervention sessions, necessitating a brief break from the study.

Activities and Materials

Three to eight play activities were used as context for baseline, intervention, generalization, and maintenance depending on the attention span and interest of each child. These types of activities have been used successfully in past research (Binger et al., 2008; Binger & Light, 2007; Cleave & Fey, 1997; Dada & Alant, 2009; Fey et al., 1997; Fey et al., 1993; Girolametto, 1988; Girolametto et al., 1996a, 1996b; Girolametto et al., 1998; Kent-Walsh et al., 2010; Pennington et al., 2009; Robertson & Ellis Weismer, 1999; Romski & Sevcik, 1996; Romski et al., 2010; Rosa-Lugo & Kent-Walsh, 2008; Tannock et al., 1992). For example, Karl enjoyed storybooks, bubbles, and pretend play with people, action figures, and animals at a park setting. Carol enjoyed storybooks and pretend play with baby dolls participating in various household activities such as eating and bathing. Mick enjoyed storybooks, bubbles, Mr. Potato Head, and stacking blocks.

The interventionists used materials available at their work settings for the activities during each session. Materials were chosen based on the developmental level and interests of the participant, as well as usefulness in encouraging production of the target vocabulary during the session. For example, if the target vocabulary consisted of the words “big” and “little,” a storybook might be chosen that described big and little animals. If the target vocabulary consisted of the words “dirty” and “clean,” the activity with a baby doll might include changing the baby’s dirty diaper. If the target vocabulary consisted of the words “hungry” and “eat,” play with Mr. Potato Head might include feeding him something to eat because he was hungry. If the target vocabulary was “hot” and “cold,” the activity with kitchen items might include preparing hot and cold pretend foods.

Research Design

This investigation utilized a within subject, adapted alternating treatments design (AATD) replicated across three participants. The AATD is a variant of the alternating treatments design (ATD) and was chosen to eliminate the two limitations of the ATD: confounding and order effects. The basic feature of the ATD is the alternation of two different interventions or treatment conditions and the observation of the effects on the same target behavior (Tawney & Gast, 1984). To minimize order effects, the treatment conditions in our study were randomly determined session by session (Sindelar, Rosenberg, & Wilson, 1985). In addition, two equivalent and functionally independent sets of words were created for the two treatment conditions to facilitate stimulus discrimination.

Procedures

Two vocabulary assessment procedures were completed prior to the baseline phase. Caregivers completed the MacArthur-Bates Communicative Development Inventories Words and Gestures (MacArthur CDI) to ensure that participants met the expressive vocabulary inclusion criterion, that is, that they were producing 50 or fewer words either verbally or via manual signs (Fenson et al., 2007). Shortly thereafter, an assessment was completed with each participant to determine the two sets of vocabulary words to be used with each intervention approach. Two sets of 25 words each, which the participants understood but did not produce, were chosen from the MacArthur-Bates CDI. One set of 25 Picture Communication Symbols™, or a photo of the child for personal names, was placed in front of the participant to determine whether the participant could name the item using natural speech, using manual sign, or by pointing directly to the line drawings. The participant needed to obtain a production score of 0% across natural speech, manual sign, and line drawings for that word to be included in the two sets of 10 targeted vocabulary words. Objective methods were used to determine that the two sets of 10 targeted vocabulary words from these original sets of 25 vocabulary words each were unique, equivalent, and functionally independent (Schlosser, 1999, 2003).

Three baseline sessions were completed by the interventionist for each vocabulary set, for a total of six baseline sessions, to establish the initial percentages of target vocabulary production (Kazdin, 1982; Kennedy, 2005). The interventionist played with the participant for a 20-min period choosing activities that were developmentally appropriate and materials that were interesting to the participant. The SLP, who was given the target vocabulary set, encouraged the production of the target vocabulary set using procedures consistent with responsivity education (Manolson, 1992). In comparison to the intervention sessions, the treating SLP produced the target vocabulary exactly 3 times rather than 10 times during the session and did not model use of the participant’s AAC system during the session. Appendix B compares the procedures that the interventionists were trained to implement, by the investigator, during each phase of the study.

Following participant completion of the six baseline sessions, language intervention sessions with the interventionist began. The purpose of the intervention sessions was to teach participants to use the target vocabulary using two intervention approaches: focused stimulation and augmented input. The order of the intervention was randomly determined. As in baseline sessions, the interventionist played with the participant during a 20-min period using developmentally appropriate materials that were interesting to the participant and targeted the specific vocabulary set. During focused stimulation sessions, the procedures were the same as in baseline except that each targeted word was produced 10 times during the session. During augmented input sessions, the procedures were the same as in baseline except that the interventionist modeled each targeted word 10 times while simultaneously using the participant’s AAC system. A teaching criterion of 12 intervention sessions per language intervention condition and a total of 24 language intervention sessions were set to permit termination of training even if the learning criterion was not attained for a language intervention approach (Schlosser, 1999, 2003).

Maintenance probes were completed by the interventionist to determine whether the production of the target vocabulary for both vocabulary sets was sustained after the learning criterion had been reached. The learning criterion was defined at 80% autonomous production of targeted vocabulary across two consecutive sessions (Schlosser, 2003). When the learning criterion was reached for one condition, training in that condition was discontinued while training in the other condition continued until either the learning or teaching criterion was reached (Schlosser, 2003). Three maintenance probes were conducted at 2 weeks, 4 weeks, and 8 weeks after reaching learning criterion (Binger et al., 2008; Kent-Walsh et al., 2010; Rosa-Lugo & Kent-Walsh, 2008). Maintenance probes, which were identical to baseline procedures, were only completed with Karl and Carol because learning criterion was not reached for either vocabulary set with Mick.

Every three sessions, generalization probes were completed during baseline, intervention, and maintenance phases of the investigation (Schlosser, 1999, 2003). Generalization probes were completed by the special education teacher and the additional SLP. The investigator trained both in the generalizations procedures; both were masked to the intervention procedures, using different activities and materials. Procedures were identical to baseline and are described in Appendix B.

Treatment integrity inter-rater reliability checks were completed for 33% of sessions across each phase of the study (Schlosser, 2003). A checklist stated the procedures to be followed for successful implementation of each phase of the study. The interventionist and the investigator, who was videotaping the session, completed the checklist independently directly following each session, to determine whether the adult consistently, variably, or did not implement each procedure. An agreement was scored when the investigator and the adult both recorded the same response. Inter-observer agreement was calculated by taking the number of agreements divided by the number of agreements plus disagreements and multiplying by 100%. Mean reliability across raters was 98%, with a range of 97% to 100%, indicating a strong agreement across raters. Regarding treatment integrity for procedures, the procedures were consistently implemented 87% of the time, variably implemented 13% of the time, and not implemented 0% of the time for Karl and Carol. For Mick, the procedures were consistently implemented 89% of the time, variably implemented 11% of the time, and not implemented 0% of the time. Treatment integrity results indicated that, across participants, most procedures were followed consistently and a few procedures were followed variably.

The outcome measure was the percent of target vocabulary autonomously produced by the child during each 20-min play session. Autonomous productions were defined as vocabulary produced by any modality, be it unaided means such as word approximations, intelligible word production, and manual sign, as well as vocabulary produced by aided means using line drawings and photos on the participant’s aided AAC systems. Word approximations were counted as autonomous productions only if both the adult and the first author/research assistant agreed the production was a close approximation of the target vocabulary. Autonomous productions could be produced in a variety of ways, including (a) spontaneously, (b) while imitating an adult production, (c) with or without adult prompting (e.g., “Tell me what you want”), (d) with or without the adult providing a choice that includes the target vocabulary (e.g., “Do you want __ or __”), or (e) in response to an adult question (e.g., “Which do you want?”; Kaiser & Hester, 1994).

Inter-rater agreement checks were completed to assure data reliability across assessment, baseline, intervention, generalization, and maintenance sessions (Kazdin, 1982; Kennedy, 2005; Schlosser, 1999, 2003). A trained research assistant masked to the procedures of the study independently viewed and recorded each child’s vocabulary productions during 33 % of the sessions for each study phase. An agreement was scored when the investigator and the independent observer both recorded the same response. Inter-observer agreement was calculated by taking the number of agreements divided by the number of agreements plus disagreements and multiplying by 100% (Schlosser, 2003). The mean inter-rater reliability across the four participants was 94%. Inter-rater reliability for Karl ranged from 80% to 100% with a mean of 89%. Inter-rater reliability for Carol ranged from 90% to 100% with a mean of 96%. Inter-rater reliability for Mick ranged from 80% to 100% with a mean of 97%.

The social validity of the study was assessed to determine whether key participants valued the intervention (Schlosser, Blischak, Belfiore, Bartley, & Barnett, 1998). All adults participating in the study completed a questionnaire to determine whether the goals of the study, the language intervention approaches, and the outcomes of the study were appropriate and reasonable for the participants. The questionnaire was provided prior to the study to allow for modification of the procedures if indicated, as well as after completion of the study. The ecological validity of the study was also assessed to determine whether key aspects of the study could be easily implemented in typical daily practice (Schlosser, 2003). On completion of the study, another questionnaire was given to the participating adults to determine whether the settings, materials, and adult participation in the study were considered reasonable and appropriate for daily implementation.

Results

Percent of Target Words Autonomously Produced

Figures 1, 2, and 3 show the percentage of target words autonomously produced by our participants during baseline, intervention, generalization, and maintenance conditions. Results are organized to show the percent of target words during focused stimulation and augmented input conditions. All three children showed an increased percentage of autonomous word production across intervention sessions during both conditions.

Figure 1.

Karl’s vocabulary production.

Figure 2.

Carol’s vocabulary production.

Figure 3.

Mick’s vocabulary production.

Karl’s performance stabilized at 90% to 100% of target vocabulary words produced after only four intervention sessions in both conditions, and he demonstrated maintenance of the newly learned vocabulary words 2, 4, and 8 weeks following completion of intervention. In addition, he was able to generalize production of the target vocabulary words across partners, activities, and materials. Carol performed at 100% of target vocabulary words after five intervention sessions for focused stimulation and six intervention sessions for augmented input; she was also able to demonstrate maintenance of learned vocabulary 2, 4, and 8 weeks following completion of intervention. In addition, Carol demonstrated generalized production of target vocabulary across communication partners, activities, and materials during all phases of the study. Mick showed a slight increase in percentage of target vocabulary words across intervention sessions in both conditions, but he failed to reach the learning criterion. His percentage of target vocabulary ranged from 0% to 80% despite the use of reduced vocabulary lists of 5 words per condition rather than 10-word lists as the other two participants due to cognitive impairment.

Comparative Treatment Effectiveness

Comparatively, both treatment approaches resulted in more rapid vocabulary production for two of the three participants when comparing number of sessions to reach learning criterion. Both treatments were equally rapid for Karl, who required only four sessions in each condition to reach learning criterion. Carol reached criterion slightly more quickly under the focused stimulation condition (five sessions) than under the augmented input condition (six sessions). Mick did not meet learning criterion with either condition, suggesting that neither treatment approach resulted in rapid and sustained learning. However, he did produce a higher percentage of target words in the augmented input condition (ranging from 0% to 80%) than in the focused stimulation (range = 0%–40%).

Social and Ecological Validation

The participating adults completed a social validity questionnaire before and after completion of the study. The results of the first questionnaire revealed that 100% of the adults believed the goals, intervention approaches, and outcomes of the study were reasonable for the specific toddler they would be working with during the study. The results of the post-study questionnaire revealed that 100% of the adults continued to believe that the goals, intervention approaches, and outcomes of the study were reasonable for the specific toddler they worked with. The same adults completed an ecological validity questionnaire at the completion of the study. The results indicated that 100% of the adults reported the settings, materials, and adult participation could be easily implemented in typical daily practice. One of the treating SLPs praised the ecological validity of the study, stating the design was straightforward and easy to understand and that any SLP could learn the intervention approach with minimal training.

Discussion

The results of this preliminary study suggest that direct intervention was effective in teaching the production of words to participants who demonstrated comprehension but not production of those words. Overall treatment effects were demonstrated for two participants, but the third experienced difficulty reaching learning criterion. The purpose of this study was to compare the effectiveness of two treatment conditions designed to increase the expressive vocabulary of toddlers who are beginning users of AAC. Comparison of our participants’ performance for both conditions failed to indicate that one condition was a more effective treatment than the other. In our study, both focused stimulation and augmented input resulted in generalized and sustained improvement of our participants’ expressive vocabulary. In addition, the results provide preliminary evidence that both approaches can result in rapid vocabulary learning, as two of the three participants learned to produce the target vocabulary after six intervention sessions or less.

A number of possible factors might help explain the results. First, qualitatively, the investigator observed that the interventionists produced the target words with increased emphasis/stress and a slower speech rate during treatment sessions for both interventions. The use of augmented input changes the nature of language production during intervention in several ways. When a communication partner uses augmented input, the interaction is slowed down and greater emphasis is placed on the vocabulary communicated via the AAC system (Binger & Light, 2007; Hustad & Beukelman, 2000). The slower rate allows the listener greater processing time, and the additional emphasis/stress provided by augmented input might also assist the AAC user. What might be surprising is that during the focused stimulation condition, the treating SLPs also used a slower speech rate and increased stress and emphasis when modeling target vocabulary, although greater emphasis and stress was reported and observed using the other approach. Nonetheless, it is possible both approaches increased target vocabulary salience and production.

Second, target vocabulary was repeatedly modeled 10 times across treatment sessions in both conditions. During baseline, the interventionist modeled each target word three times which did not result in marked increases in vocabulary production. Yet, when the interventionist modeled the target word 10 times, increases were observed across all children. Prior studies reported increases in vocabulary using either augmented input alone (Binger & Light, 2007; Bruno & Trembath, 2006; Dada & Alant, 2009; Harris & Reichle, 2004) or responsivity education with the addition of augmented input (Binger et al., 2008; Kent-Walsh et al., 2010; Romski et al., 2010; Rosa-Lugo & Kent-Walsh, 2008). No studies incorporated repeated modeling in the form of focused stimulation without augmented input. The present study indicates that focused stimulation also facilitates vocabulary production with toddlers using a range of AAC methods. This study also indicates that, despite repeated vocabulary modeling, the toddler with a moderate cognitive impairment did not learn to produce vocabulary at the same rate as the other two. Mick did not reach learning criterion following 12 treatment sessions with either treatment while the two other participants easily reached learning criterion within the first 4 to 6 sessions.

Third, the present study used a facilitative language environment, which included play routines and a child-centered approach. All sessions incorporated responsivity (Manolson, 1992), which has been found to be an effective framework for facilitating language production in young children with language delays when used alone (Girolametto, 1988; Gladfelter, Wendt, & Subramanian, 2011; Pennington et al., 2009; Tannock et al., 1992); in combination with focused stimulation (Girolametto et al., 1996a, 1996b; Girolametto et al., 1998; Gladfelter et al., 2011); and in combination with augmented input (Binger et al., 2008; Binger et al., 2011; Binger & Light, 2007; Kent-Walsh et al., 2010; Romski et al., 2010; Rosa-Lugo & Kent-Walsh, 2008). In our study, the treating SLPs provided numerous communicative opportunities for the toddlers to produce the target vocabulary as a result of high rates of interventionist input, which has been found to be an important element for facilitating communication output in preschool classrooms with children learning to communicate with AAC (Brady, Herynk, & Fleming, 2010). In addition, age appropriate play scenarios, as chosen by each toddler, were used as contexts for intervention. Such play routines have been widely used as successful contexts in intervention studies with preschoolers demonstrating language disorders for teaching vocabulary and various grammatical structures (Cleave & Fey, 1997; Fey et al., 1997; Fey et al., 1993; Girolametto, 1988; Robertson & Ellis Weismer, 1999; Tannock et al., 1992), and have also been used with children demonstrating severe communication disorders who use AAC (Binger & Light, 2007; Romski et al., 2010). Intervention was primarily child-centered, in contrast to adult-directed approaches in which the adult chooses and imposes the intervention activities and materials on the child to meet the specified intervention goals (McCauley & Fey, 2006).

Fourth, target vocabulary for each treatment was systematically selected. Vocabulary was chosen for the purpose of communicating essential messages, as the participants understood the vocabulary receptively, but did not yet produce it. Target vocabulary included both core vocabulary, with combinatorial power (Banajee, Dicarlo, & Stricklin, 2003), and fringe vocabulary specific to play activities (Beukelman & Mirenda, 2013). All vocabulary was chosen from words frequently produced by typically developing and late-talking toddlers (Rescorla & Alley, 2001). In addition, each participant’s caregiver completed the second edition of the MacArthur-Bates CDI (Fenson et al., 2007) prior to assessment, to identify vocabulary for the assessment that participants understood but did not produce in any communication modality. This careful, systematic selection of vocabulary may have facilitated vocabulary production across two of the three participants.

Fifth, the two toddlers who reached learning criterion engaged in a more consistent and authentic participation with their adult communication partners. Authentic participation is a social, pragmatic perspective in which children use their emerging skills, including motor skills, categorical skills, verbal skills, imitative skills, gestural skills, play skills, and memory skills, to advance their experience and to find and share its meaning with others. Authentic participation encourages selective and sustained attention, active engagement, a desire to participate, and an understanding of the goal of the activity (Nelson, 2007). Nelson (2007) states that children seek to match their understanding of a situation with the words used by others in that situation, resulting in word production. The process of vocabulary production cannot effectively occur if the child is not authentically engaged in social interactions with the communication partner. Karl and Carol were observed to participate with adult communication partners throughout all phases of the study more consistently and authentically. However, Mick demonstrated varying levels of participation when completing intervention sessions, which might have negatively impacted his ability to produce target vocabulary, despite decreasing the complexity of the AAC system and allowing more time for processing and responding.

Sixth, individual toddler characteristics might have contributed to the production of target vocabulary, including age appropriate cognitive and receptive language skills, better attention spans, and learning styles that were supported by the intervention approach. Mick was the only participant to demonstrate a moderate cognitive impairment, a receptive language delay, and a short attention span. Several studies have demonstrated that toddlers with intellectual disabilities may benefit from more intense and prolonged treatment when learning to communicate and produce early vocabulary (Fey et al., 2006; Warren et al., 2008; Yoder & Warren, 2002). While these studies did not focus on toddlers who used AAC, and the interventions were not the same as the present study, the participants were similar to Mick in age, level of cognitive impairment, and communicative status, receptively and expressively. The present study provides further evidence that for toddlers with moderate cognitive impairment, intervention might need to be more intense and of longer duration than the present study to facilitate production of target vocabulary, even with the introduction of focused stimulation or augmented input.

Limitations

Several limitations of the study must be considered when interpreting the results. First, relatively few toddlers participated in this study, and replication of the study is required to strengthen the external validity and generality of the results (Kazdin, 1982). Only two of the three participants successfully completed the investigations. Another limitation of the study was the research design. We did not conduct a component analysis of both conditions at different intensity levels (i.e., augmented input at a different rate), so we cannot separate out the effects of a focused stimulation with those of augmented input. A multiple baseline with ATD across participants would add experimental controls and make possible relative comparisons in treatment effectiveness and efficiency. A third limitation of the study was the AAC systems that the participants used to facilitate communication. All of the participants used either unaided AAC or aided non-electronic AAC systems. None of the toddlers used voice output communication aids. Further research is needed to determine whether the use of voice output communication aids would impact ability to learn to produce vocabulary with the two language intervention approaches in the study. Another limitation of the study was the lack of success of the interventions with the toddler demonstrating a moderate cognitive impairment, delayed receptive language skills, and a shorter attention span. Further research is needed to determine whether a toddler with these difficulties might benefit from more intense weekly sessions and longer duration.

Conclusion

The current preliminary investigation indicated that the two language intervention approaches facilitated production of novel vocabulary with toddlers who receive and use AAC. Specifically, the investigation demonstrated that training with both focused stimulation and augmented input can result in improved vocabulary production with toddlers who are actively engaged in activities with selective and sustained attention. However, these intervention approaches might not be as facilitative with toddlers who experience more significant disabilities. For toddlers with cognitive impairment, delayed receptive language skills, and/or shorter attention spans, it is possible that additional supports might be needed to increase authentic participation, such as increased prompting, more intensive sessions, and a longer duration of treatment.

Footnotes

Appendix

Appendix B

Comparison of Baseline, Probe, and Intervention Procedures

		Intervention
Procedures	Baseline generalization probe maintenance probe	Focused stimulation	Augmented input
Wait to respond and listen to what the participant says.	X	X	X
Allow the child to lead.	X	X	X
After allowing the participant to lead, actively join in play.	X	X	X
Play at a face-to-face level.	X	X	X
Ask many types of questions such as what, where, and how.	X	X	X
Wait expectantly for the participant to respond and tell the participant, “It’s your turn.”	X	X	X
Respond by taking a turn in a similar way to the participant.	X	X	X
Imitate the participant’s verbalization by repeating exactly what he or she said.	X	X	X
Use a variety of labels by naming many items during play.	X	X	X
Expand what is said by imitating the participant and adding one to two additional words.	X	X	X
Extend what is said by expanding and then adding a comment or two about the topic.	X	X	X
Produce the target vocabulary three times during play.	X
Produce the target vocabulary 10 times during play		X	X
Do not model use of the participant’s AAC system during play.	X	X
Model each target vocabulary on the participant’s AAC system after saying the vocabulary orally.			X

Note. AAC = augmentative and alternative communication.

Acknowledgements

The authors would like to thank Susan Holloway and Carla Hudson Kam, both of whom served as members of the first author’s dissertation committee, in addition to Katie Krabbenshmidt, Betsy Fletcher, and Brenna Gall for their assistance with the project. The authors would also like to thank the center administrators, staff, parents, and children who made this study possible

Authors’ Note

This study was based on a doctoral dissertation completed in partial fulfillment of the first author’s PhD program through the Joint Doctoral Program in Special Education at San Francisco State University and the University of California at Berkeley.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

References

Anderson

(2001). Augmentative communication and autism: A comparison of sign language and the Picture Exchange System (Doctoral dissertation). Available from http://www.lib.berkeley.edu/

Banajee

Dicarlo

Stricklin

(2003). Core vocabulary determination for toddlers. Augmentative and Alternative Communication, 19, 67–73.

Beukelman

D. R.

Mirenda

(2013). Augmentative and alternative communication: Supporting children and adults with complex communication needs (4th ed.). Baltimore, MD: Paul H. Brookes.

Binger

Kent-Walsh

Berens

Del Campo

Rivery

(2008). Teaching Latino parents to support the multi-symbol message productions of their children who require AAC. Augmentative and Alternative Communication, 24, 323–338.

Binger

Light

(2007). The effect of aided AAC modeling on the expression of multi-symbol messages by preschoolers who use AAC. Augmentative and Alternative Communication, 23, 30–43.

Binger

Maguire-Marshall

Kent-Walsh

(2011). Using aided AAC models, recasts, and contrastive targets to teach grammatical morphemes to children who use AAC. Journal of Speech, Language and Hearing Research, 54, 160–176.

Brady

N. C.

Herynk

J. W.

Fleming

(2010). Communication input matters: Lessons from prelinguistic children learning to use AAC in preschool environments. Early Childhood Services, 4, 141–154.

Branson

Demchak

(2009). The use of augmentative and alternative communication methods with infants and toddlers with disabilities: A research review. Augmentative and Alternative Communication, 25, 274–286.

Bruno

Trembath

(2006). Use of aided language stimulation to improve syntactic performance during a weeklong intervention program. Augmentative and Alternative Communication, 22, 300–313.

10.

Cleave

P. L.

Fey

M. E.

(1997). Two approaches to the facilitation of grammar in children with language impairments: Rationale and description. American Journal of Speech-Language Pathology, 6, 22–32.

11.

Dada

Alant

(2009). The effect of aided language stimulation on vocabulary acquisition in children with little or no functional speech. American Journal of Speech-Language Pathology, 18, 50–64.

12.

DiCarlo

C. F.

Stricklin

Banajee

(2001). Effects of manual signing on communicative verbalizations by toddlers with and without disabilities in inclusive classrooms. Journal of the Association for the Severely Handicapped, 26, 120–126.

13.

Fenson

Marchman

V. A.

Thal

D. J.

Dale

P. S.

Reznick

J. S.

Bates

(2007). MacArthur-Bates communicative development inventories (2nd ed.). Baltimore, MD: Paul H. Brookes.

14.

Fey

M. E.

Cleave

P. L.

Long

S. H.

(1997). Two models of grammar facilitation in children with language impairments: Phase 2. Journal of Speech, Language, and Hearing Research, 40, 5–19.

15.

Fey

M. E.

Cleave

P. L.

Long

S. H.

Hughes

D. L.

(1993). Two approaches to the facilitation of grammar in children with language impairment: An experimental evaluation. Journal of Speech and Hearing Research, 36, 141–157.

16.

Fey

M. E.

Warren

S. F.

Brady

N. C.

Finestack

Brendin-Oja

Fairchild

. . . Yoder

P. J.

(2006). Early effects responsivity education/prelinguistic milieu teaching for children with developmental delays and their parents. Journal of Speech, Language, and Hearing Research, 49, 526–547.

17.

Girolametto

(1988). Improving the social-conversational skills of developmentally delayed children: An intervention study. Journal of Speech and Hearing Disorders, 53, 156–167.

18.

Girolametto

Pearce

Weitzman

(1996a). The effects of focused stimulation for promoting vocabulary in children with delays: A pilot study. Journal of Childhood Communication Development, 17, 39–49.

19.

Girolametto

Pearce

Weitzman

(1996b). Interactive focused stimulation for toddlers with expressive vocabulary delays. Journal of Speech and Hearing Research, 39, 1274–1283.

20.

Girolametto

Weitzman

Clements-Baartman

(1998). Vocabulary intervention for children with Down syndrome: Parent training using focused stimulation. Infant-Toddler Intervention: A Transdisciplinary Journal, 8, 109–126.

21.

Gladfelter

Wendt

Subramanian

(2011). Evidence-based speech and language intervention techniques for the birth-to-3 population. Evidence-Based Practice Briefs, 5, 41–50.

22.

Goossens’

(1989). Aided communication intervention before assessment: A case study of a child with cerebral palsy. Augmentative and Alternative Communication, 5, 14–26.

23.

Harris

M. D.

Reichle

(2004). The impact of aided language stimulation on symbol comprehension and production in children with moderate cognitive disabilities. American Journal of Speech-Language Pathology, 13, 155–167.

24.

Hustad

K. C.

Beukelman

(2000). Integrating AAC strategies with natural speech in adults. In Beukelman

Yorkston

K. M.

Reichle

(Eds.), Augmentative and alternative communication for adults with acquired neurological disorders (pp. 86-106). Baltimore, MD: Paul H. Brookes.

25.

Iacono

T. A.

Duncum

J. E.

(1995). Comparison of sign alone and in combination with an electronic communication device in early language intervention: A case study. Augmentative and Alternative Communication, 11, 249–259.

26.

Iacono

Mirenda

Beukelman

(1993). Comparison of unimodal and multimodal AAC techniques for children with intellectual disabilities. Augmentative and Alternative Communication, 9, 83–94.

27.

Kaiser

A. P.

Hester

P. P.

(1994). Generalized effects of enhanced milieu teaching. Journal of Speech and Hearing Research, 37, 1320–1340.

28.

Kazdin

A. E.

(1982). Single-case research designs: Methods for clinical and applied settings. New York, NY: Oxford University Press.

29.

Kennedy

C. H.

(2005). Single case designs for educational research. Boston, MA: Allyn & Bacon.

30.

Kent-Walsh

Binger

Hasham

(2010). Effects of parent instruction on the symbolic communication of children using AAC during storybook reading. American Journal of Speech-Language Pathology, 19, 97–107.

31.

Manolson

(1992). It takes two to talk: A parent’s guide to helping children communicate. Toronto, Ontario, Canada: The Hanen Centre.

32.

McCauley

R. J.

Fey

M. E.

(2006). Treatment of language disorders in children. Baltimore, MD: Paul H. Brookes.

33.

Nelson

(2007). Young minds in societal worlds: Experience, meaning, and memory. Cambridge, MA: Harvard University Press.

34.

Pennington

Thomson

James

Martin

McNally

(2009). Effect of it takes two to talk—The Hanen program for parents of preschool children with cerebral palsy: Findings from an exploratory study. Journal of Speech, Language and Hearing Research, 52, 1121–1138.

35.

Remington

Clark

(1983). Acquisition of expressive signing by autistic children: An evaluation of the relative effects of simultaneous communication and sign-alone training. Journal of Applied Behavior Analysis, 16, 315–328.

36.

Rescorla

Alley

(2001). Validation of the Language Development Survey (LDS): A parent report tool for identifying language delay in toddlers. Journal of Speech, Language, and Hearing Research, 44, 434–445.

37.

Robertson

S. B.

Ellis Weismer

(1999). Effects of treatment on linguistic and social skills in toddlers with delayed language development. Journal of Speech, Language and Hearing Research, 44, 1234–1248.

38.

Romski

M.A.

Sevcik

R.A.

(1996). Breaking the sound barrier: Language development through augmented means. Baltimore, MD: Paul H. Brookes Publishing.

39.

Romski

M. A.

Sevcik

R. A.

Adamson

L. B.

Cheslock

Smith

Barker

R. M.

Bakeman

(2010). Randomized comparison of augmented and nonaugmented language interventions for toddlers with developmental delays and their parents. Journal of Speech, Language and Hearing Research, 53, 350–364.

40.

Rosa-Lugo

L. J.

Kent-Walsh

(2008). Effects of parent instruction on communicative turns of Latino children using augmentative and alternative communication. Communication Disorders Quarterly, 30, 49–61.

41.

Schlosser

R. W.

(1999). Comparative efficacy of intervention in augmentative and alternative communication. Augmentative and Alternative Communication, 15, 56–68.

42.

Schlosser

R. W.

(2003). The efficacy of augmentative and alternative communication: Towards evidence-based practice. New York, NY: Academic Press.

43.

Schlosser

R. W.

Blischak

D. M.

Belfiore

P. J.

Bartley

Barnett

(1998). Effects of synthetic speech output and orthographic feedback on spelling in a student with autism: A preliminary study. Journal of Autism and Developmental Disorders, 28, 309–320.

44.

Schlosser

R.W.

Sigafoos

(2006). Augmentative and alternative communication interventions for persons with developmental disabilities: narrative review of comparative single-subject experimental studies. Research in Developmental Disabilities, 27, 1-29.

45.

Sindelar

P. T.

Rosenberg

M. S.

Wilson

R. J.

(1985). An adapted alternating treatments design for instructional research. Education & Treatment of Children, 8, 67–76.

46.

Tannock

Girolametto

Siegal

(1992). Language intervention with children who have developmental delays: Effects of an interactive approach. American Journal of Mental Retardation, 97, 145–160.

47.

Tawney

J. W.

Gast

D. L.

(1984). Single subject research in special education. Columbus, OH: Charles E. Merrill.

48.

Warren

S. F.

Fey

M. E.

Finestack

L. H.

Brady

N. C.

Bredin-Oja

S. L.

Fleming

K. K.

(2008). A randomized trial of longitudinal effects of low-intensity responsivity education/prelinguistic milieu teaching. Journal of Speech, Language and Hearing Research, 51, 451–470.

49.

Yoder

P. J.

Warren

S. F.

(2002). Effects of prelinguistic milieu teaching and parent responsivity education on dyads involving children with intellectual disabilities. Journal of Speech-Language-Hearing Research, 45, 1158–1174.