Find an experimental research study on the topic chosen in Week One for your Final Research Proposal. You may choose to include an experimental study which was included in the literature review you us
ORIGINAL ARTICLE Comparing Three Augmentative and Alternative Communication Modes for Children with Developmental Disabilities Larah van der Meer &Robert Didden & Dean Sutherland &Mark F. O’Reilly & Giulio E. Lancioni &Jeff Sigafoos Published online: 8 May 2012 # Springer Science+Business Media, LLC 2012 AbstractWe compared acquisition, maintenance, and preference for three AAC modes in four children with developmental disabilities (DD). Children were taught to make general requests for preferred items (snacks or play) using a speech- generating device (SGD), picture-exchange (PE), and manual signs (MS). The effects of intervention were evaluated in a multiple-probe across participants and alternating- treatments design. Preference probes were also conducted to determine if children would choose one AAC mode more frequently than the others. During intervention, all four children learned to request using PE and the SGD, but only two also reached criteria with MS. For the AAC preference assessments, three participants chose the SGD most frequently, while the other participant chose PE most frequently. The results suggest that children’s preference for different AAC modes can be assessed J Dev Phys Disabil (2012) 24:451–468 DOI 10.1007/s10882-012-9283-3 L. van der Meer :J. Sigafoos Victoria University of Wellington, Wellington, New Zealand R. Didden Radboud University Nijmegen, Nijmegen, The Netherlands D. Sutherland University of Canterbury, Christchurch, New Zealand M. F. O’Reilly The Meadows Center for the Prevention of Educational Risk, University of Texas at Austin, Austin, TX, USA G. E. Lancioni University of Bari, Bari, Italy L. van der Meer (*) School of Educational Psychology and Pedagogy, Victoria University of Wellington, PO Box 17-310, Karori, 6147 Wellington, New Zealand e-mail: [email protected] during the early stages of intervention and that their preferences may influence acquisition and maintenance of AAC-based requesting responses.
KeywordsAugmentative and alternative communication.
Developmental disabilities.
Manual sign.
Picture-exchange.
Speech-generating devices Children with developmental disabilities (DD) often present with significant deficits in speech and language development. To enable these children to communicate, intervention typically involves teaching the use of augmentative and alternative communication (AAC; Beukelman and Mirenda2005;Schlosser2003a). Three common AAC modes are speech-generating devices (SGDs; Lancioni et al.2007), picture exchange (PE) or more specifically the Picture Exchange Communication System (PECS; Bondy and Frost1994; Bondy and Frost2001), and manual signing (MS; Lloyd, Fuller, & Arvidson,1997). Data indicate that all three of these AAC modes can be successfully taught to children with DD (Flippin et al.2010; Goldstein 2002; Hart and Banda2010; Lancioni et al.2007; Preston and Carter2009; Rispoli et al.2010; Schlosser and Wendt2008a; Schlosser and Wendt2008b; Sulzer-Azaroff et al.2009; Tien2008; van der Meer and Rispoli2010; Wendt2009).
While there is evidence to support the use of each of these three AAC modes, debate continues regarding the relative efficacy of these three options for individuals with DD (Mirenda2003; Schlosser and Sigafoos2006). To shed some empirical light on this debate, one can turn to the results of several studies that have compared acquisition of PE versus MS (Adkins and Axelrod2001; Gregory et al.2009; Rotholz et al.1989; Tincani2004), as well as SGDs versus PE (Beck et al.2008; Bock et al.
2005). Few studies have compared SGD and MS (Iacono and Duncum1995; Iacono et al.1993; van der Meer et al.2012). One consistent finding from these comparison studies is that there seems to be no large or consistent differences in terms how effectively and efficiently the compared AAC modes can be taught to participants with DD.
In light of such evidence, Sigafoos et al. (2003) proposed that clinicians might profitably examine the extent to which individuals show a preference for using one AAC mode over another. Along these lines, a number of studies have assessed preferences for different AAC modes (Cannella-Malone et al.2009; Sigafoos et al.
2009; Sigafoos et al.2005; Son et al.2006; Soto et al.1993; Winborn-Kemmerer et al. 2009). In these studies, the participant’s preference for using one mode of communication over another was assessed using a structured choice-making arrange- ment (Sigafoos1998). Specifically, participants were taught to use two different AAC options (e.g., SGD and PE) for functional communication (e.g., requesting a snack) and were then given the opportunity to choose which AAC mode to use during subsequent requesting opportunities. A communication system was considered pre- ferred when it was consistently chosen more often than the other option.
A systematic review of this AAC-preference literature (van der Meer et al.2011b) indicated that individuals with DD do in fact often demonstrate a preference for using (choosing) one AAC mode over another. However, this existing group of studies is limited in a number of ways. First, preference assessments were only undertaken after participants already learned to use each communication option. This post-hoc 452 J Dev Phys Disabil (2012) 24:451–468 approach effectively prevented an evaluation of whether preference can be incorpo- rated into, and identified during, the initial stages of AAC intervention. Second, only one study (Soto et al.1993) collected maintenance data. It is therefore unclear whether employing preferred AAC systems improves intervention outcomes in terms of long-term maintenance of newly acquired communication skills or if preferences remain stable over time. Third, the majority of studies reviewed only assessed preference between two (SGD and PE) AAC modes (van der Meer et al.2011b).
Although one study (Iacono and Duncum1995) compared the use of MS versus SGD and inferred a preference for one over the other based upon effectiveness of use, none of the studies assessed preferences among all three of these commonly used AAC modes (i.e., SGD, PE, and MS).
Along those lines, van der Meer et al. (2012) addressed each of these limitations.
They compared acquisition of augmented requesting responses using an iPod®-based SGD versus MS. Preference assessments were implemented throughout the interven- tion in order to determine whether four participants (with DD, aged 5 to 10 years) made relatively greater progress with the SGD or MS. Results showed that all four participants learned to request preferred objects. Three participants exhibited a preference for using the SGD, while one participant demonstrated a preference for using MS. Additionally, participants were more proficient at using their preferred AAC option and maintenance of communication skills was better with their preferred option.
The present study was designed to systematically replicate and extend the work of van der Meer et al. (2012) by including more participants and comparing acquisition of, and preference for, SGD, MS, and PE. Based on the results of the van der Meer et al. (2012) study, we hypothesized that the four children participating in the current study would show a preference for using one AAC mode over the other two, that these preferences would vary across children, and that the children would learn to request preferred stimuli more quickly with their most preferred AAC mode.
Method Participants Four children were recruited due to their severely limited speech from a child- care center for children with DD. All four participants met the following criteria:
(a) diagnosis of intellectual/developmental disability or autism spectrum disorder (ASD), (b) less than 18 years of age, (c) very limited or no communication skills as determined by an age equivalency of 2 years or less on the Communication Domain of the Vineland–Z, Dutch edition (Sparrow et al.2003), (d) no auditory or visual impairments that would interfere with the use of AAC, and (e) sufficient motor skills to operate/perform the motor actions required to use each of the three AAC modes.
Joe was a 12-year-old male diagnosed with ASD. On the Vineland–Z (Sparrow et al.2003), Joe received age equivalencies of 1:2 (years:months) for communication, 1:4 for daily living skills, and 1:1 for socialization. Joe did not have any spoken language, but made sounds that were presumed to be his way of expressing how he J Dev Phys Disabil (2012) 24:451–468 453 was feeling (e.g., happy versus sad). He also appeared to communicate his wants and needs by taking a person’s hand and leading them to an object. Joe’s teachers used a picture communication board to explain routine activities for the day (toilet, food and drink, gym, bus, free choice, and outside play). Teachers had also introduced him to MS for receptive language. He did not have any prior experience with SGDs, PE, or MS as a communication mode for requesting access to preferred objects. Joe’s fine and gross motor skills appeared to be adequate for his chronological age. He demonstrated frequent stereotypical and repetitive behaviors, such as flapping small toys and pieces of paper in front of his eyes.
Sam was a 6-year-old male diagnosed with childhood disintegrative disorder and intellectual disability. He received age equivalencies on the Vineland–Z (Sparrow et al.2003) of 1:2, 1:8, and 0:11 (years:months) for the communication, daily living skills, and socialization domains, respectively. Sam did not have any spoken lan- guage. He would take a person’s hand and lead them to objects to seemingly express his wants and needs. He also made sounds that were thought to be indications of disapproval. His teachers tried to use MS when communicating with Sam, but he did not appear to show any interest in using MS to make requests. As was the case for Joe, Sam did not have any prior experience with SGDs, PE, or MS as a communi- cation mode for requesting access to preferred objects.
Saskia was a 10-year-old female with Angelman syndrome. She received an age equivalency of 1:4 (years:months) for the communication domain and 1:0 for both the daily living skills and socialization domains of the Vineland–Z (Sparrow et al.
2003). Saskia was able to speak several single words, mostly in the form of echolalia.
She would often take people’s hands to seemingly direct them to what she wanted, to open things, or to clap for her. Saskia had some experience with MS and was able to produce the signs for FINISHED and OPEN. She had no further experience with other forms of AAC. She exhibited difficulty with social interaction and engaged in stereotypic and repetitive behaviors. For example, she seemed more interested in adults and, although she appeared to enjoy watching other children play, she would push them away if they approached her. She also flapped keys and other objects in front of her eyes.
Nicky was a 13-year-old female diagnosed with pervasive developmental disorder not otherwise specified (PDD-NOS). Nicky received age equivalencies on the Vine- land–Z (Sparrow et al.2003) of 1:3, 1:1, and 1:3 (years:months) for the commu- nication, daily living skills, and socialization domains respectively. She was able to verbalize several single words, but generally only made babbling sounds. She had previously received MS training and was able to produce several signs, including OPEN, EAT, and CIRCLE TIME. Nicky appeared to understand symbols from her daily picture communication book and from routine activities. She was able to match picture cards and had received 1 year of PECS training, but reportedly had made little progress. She had received no further training in the use of AAC for requesting preferred objects. Nicky was able to maintain good eye contact and seek social contact, but she was said to be very excitable and did not seem to understand social boundaries. She was not able to play cooperatively with other children. Nicky often cried in an apparent attempt to gain attention. Nicky’s fine motor skills were adequate for her developmental level. She was able to walk on her own, although she was hypotonic.
454 J Dev Phys Disabil (2012) 24:451–468 Setting and Intervention Context Participants were recruited from a Dutch childcare center for children with DD. The procedures related to this study were conducted in a small therapy room across the hall from the children’s main classrooms. Sessions occurred during morning and afternoon snack/leisure activities. The procedures were implemented in a one-to-one context consisting of the trainer (first author) and one participant at a time. All instructions/interactions with the participants and responses programmed on the AAC systems were in the Dutch language.
Preferred Stimuli Stimuli that the children seemed to prefer, and which would be appropriate for them to request during a snack or leisure activity, were identified by a systematic two-stage stimulus preference assessment (Green et al.2008). Stage 1 of the preference assessment involved an indirect assessment in which teachers were asked to list foods, sensory stimuli, and toys that the participants appeared to enjoy and would be appropriate for the intervention.
For Stage 2, three to six of the most preferred food or play stimuli were then selected for a direct stimulus assessment. The direct preference assessment for Joe focused on identifying preferred foods because his intervention occurred during a snack activity and his teachers reported that he seemed to be highly motivated by snack foods. The direct preference assessment for Sam, Saskia, and Nicky, in contrast, focused on identifying preferred toys because their intervention occurred during a play activity and their teachers had concerns about using food reinforcers.
Stage 2 involved the simultaneous presentation of multiple items, without replace- ment (DeLeon and Iwata1996; Duker et al.2004). Each participant was presented with an array of items from Stage 1 (random placement) and allowed to select one item. Items were not replaced once they had been selected, thereby eliminating the chance of the participant choosing only one or a few items, as well as allowing the trainer to develop a rank order of items in terms of preference. The top three food items for Joe and top three play items for Sam, Saskia, Nicky were identified by calculating a rank order of the percentage of times that the stimuli were selected.
Across two to three sessions, each item was offered a total of nine times. Rank orders were calculated using the formula: Number of Selections/Number of Offers x 100 %.
Preferred stimuli for Joe included‘skittles’lollies (75 %),‘tumtum’lollies (33 %), and potato chips (32 %). Preferred stimuli for Sam included a puzzle (60 %), venting ball (36 %), and windmill (33 %). Preferred stimuli for Saskia included a musical toy (82 %), keys and lanyard (39 %), and bubbles (31 %). Preferred items for Nicky included a tea set (69 %), dolls (56 %), and a mirror (32 %).
Speech-Generating Device (SGD) Participants were taught to request preferred toys or snacks using an Apple iPod Touch® with Proloquo2Go™software. The iPod was placed inside an iMainGo®2 speaker case to increase sound amplification. The iPod was configured to show a single page containing two graphic symbols (2.5 × 2.5 cm), representing requests for J Dev Phys Disabil (2012) 24:451–468 455 SNACKSandPLAY. The messages were programmed in Dutch. Touching each symbol activated corresponding synthetic speech-output (i.e.,“I want something to eat.”,and“I want to play.”).
Picture Exchange (PE) Participants were also taught to request their preferred toys or snacks using PE. Three (6 × 6 cm) symbols from the PECS 2009 Dictionary (Pyramid Educational Products 2009) were affixed with Velcro™to a 19 × 13 cm card. One symbol contained a colored line drawing showing two hands reaching out and the wordsI WANT.The second symbol consisted of a colored line drawing of various different toys and the wordsTO PLAY.The third symbol consisted of a colored line drawing of various snack items and the messageSOMETHING TO EAT.All words were written in Dutch. The symbols were randomly allocated to the six (6 × 6 cm) panels of the card.
Manual Signing (MS) Participants were taught to request their preferred toys or snacks using signs from the Dutch sign language system for children (Nederlands Gebarencentrum2006). Par- ticipants were taught the sign for SNACK or PLAY. The MS option was represented by a laminated photograph (15 × 8 cm) of the trainer making the hand formations for the signs for SNACK and PLAY.
Response Definitions and Measurement For SGD use, correct responding was defined as independently (without a gestural or verbal prompt) touching the symbol on the screen of the SGD to activate the corresponding speech output in exchange for a desired item from the trainer. MS was defined as independent (without a gestural or verbal prompt) hand gestures to produce correct signs in exchange for a desired item from the trainer. For PE, participants were required to independently (without gestural or verbal prompt) place theI WANTand corresponding (SNACKSorPLAY) symbols—depending on whether they were requesting snacks or play—onto the two panels (6 × 6 cm) provided on a separate (21 × 7 cm) card in exchange for the desired item from the trainer.
The percentage of correct responses (requests) was calculated for each session.
Each session consisted of 10 offers to request snack or play items. The SGD target response for Joe was touching theSNACKsymbol on the SGD to activate the message“I want a snack.”His target response for PE was placing theI WANTand SOMETHING TO EATsymbols on the separate card. ThePLAYsymbol (SGD and PE) was intended as a distracter. Joe’s target response for MS was to produce the manual sign for SNACK. The PLAY sign (on the laminated card) was intended as a distractor. The SGD target response for Sam, Saskia, and Nicky was touching the PLAYsymbol on the SGD to activate the message“I want to play.”Their target response for PE was placing theI WANTandTO PLAYsymbols on the separate card.
TheSNACKsymbol (SGD and PE) was intended as a distracter. The MS target response for Sam, Saskia, and Nicky was to produce the manual sign for PLAY. The SNACK sign (on the laminated card) was intended as a distractor.
456 J Dev Phys Disabil (2012) 24:451–468 Experimental Design The study included the following phases arranged in a multiple-probe across partic- ipants design (Kennedy2005): Baseline, Intervention, Preference Assessment (throughout Intervention, Post-Intervention, and Follow-Up), Post-Intervention, and Follow-Up. An alternating-treatments design was embedded within each phase of the multiple-probe to compare children’s performance with the SGD, PE, and MS options.
Session Schedule Two to four sessions were conducted 5 days per week. Each session lasted about 10 min and consisted of 10 discrete trials. The AAC option available (i.e., SGD, PE, or MS) was counterbalanced across sessions to prevent order effects (Kennedy2005).
For all sessions, the participant and trainer were seated next to each other at a table with one or two additional reliability and procedural integrity observers seated nearby.
Once a participant showed an increase in requesting behavior above the level established in baseline for three consecutive sessions with at least one of the AAC options, training commenced with the next participant. Training was first provided to Joe, then Sam, Saskia, and finally Nicky. Training was provided in this order in accordance with results from the baseline phase (i.e., the participant with the most stable baseline commenced intervention first). Once a participant reached criterion for one AAC condition (i.e., 80 % correct requesting across three consecutive sessions for each AAC option), maintenance probes were initiated with that system while the other communication systems continued to be taught using the intervention proce- dures. One maintenance session with the acquired AAC device was conducted after three sessions with each of the AAC options still being taught.
Procedures Because participants were considered to be at the beginning stages of AAC interven- tion, they were taught to make general requests for either snacks or toys from which they could select one highly preferred item after each request. However, to ensure some level of symbol discrimination, the distractor symbols/signs were included on the AAC options. If participants requested a snack when they were undertaking training to request a toy or vice versa, the trainer explained:We are learning to request toys (snack) at the moment, you can request a toy (snack) another time. It was considered natural to provide them with this feedback when they activated the non- target symbols/produced the non-target signs, but not to reinforce it with preferred tangibles. Similarly, producing MS to request snacks or toys during SGD or PE sessions was ignored in order to bring the use of each device under stimulus control.
BaselineDuring baseline, a tray containing three different snack (play) items was placed on the table in view, but out of the participants’reach. The SGD, PE, and MS option (represented by the photograph of the trainer making the two signs) were randomly placed on different sides of the table for each baseline session. Each session J Dev Phys Disabil (2012) 24:451–468 457 involved 10 discrete trials for snacks or toys. The session began with the trainer telling the participant:Here is a tray of snacks (toys), let me know if you want something. After 10 s, the trainer moved the tray within reach and allowed the participant to take one item. This 10-s fixed time schedule of reinforcement was provided to ensure continued motivation to participate in sessions. When offering snacks, participants were allowed to select one item from the tray, which was then replenished before the next offer. When offering the tray of toys, participants were allowed to select one toy and play with it for approximately 30 s before it was returned to the tray. SGD, PE, and MS responses were recorded, but had no programmed consequences.
InterventionThis phase was conducted in a discrete trial format until participants reached criterion (i.e., 80 % correct requesting across three consecutive sessions for each AAC option). The SGD, PE, or the MS option was placed on the table (counter- balanced across trials) within reach of the child in accordance with the alternating treatments design. Each trial consisted of the trainer pointing to a tray of snacks (toys) and saying:Here’s a tray of snacks (toys). Let me know if you want something.
Training involved a 10-s time delay between the verbal cue (i.e.,Let me know if you want something.) and the use of graduated guidance to prompt a correct request.
Graduated guidance involved use of the least amount of physical guidance necessary to ensure the child made a correct request, while simultaneously explaining the required response (e.g.,Press PLAY to ask to play with a toy.orMove your hand to your mouth to make the sign forEAT. orPut the I WANT and PLAY pictures on the velcro strips). Immediately after the child had used the SGD to produce the correct synthesized speech output, or had placed the appropriate symbols on the Velcro strips, or had made the correct manual sign, the trainer moved the tray containing the snacks (or toys) within reach of the participant. The participant was allowed to select one item from the tray and consume the chosen snack or play with the chosen toy for about 30 s. After this, the next trial was initiated.
Procedural ModificationsJoe did not reach criterion for each communication system during the initial intervention phase so he received a modified intervention. The modification was developed in response to what appeared to be a problem in teaching him to discriminate among the different symbols. Therefore, thePLAYsymbol was removed from the SGD and PE options (see the 1 Symbol phase of Fig.1). The only icon displayed on the SGD screen was therefore theSNACKicon, which was also enlarged to fit the entire screen. Joe was only required to press this icon to activate the voice-output in order to make a correct request for a preferred snack item. For the PE option, he no longer had to discriminate between theSNACKandPLAYsymbols. For a correct request he had to place theI WANTandSOMETHIG TO EATsymbols onto the two locations provided on the separate card in exchange for the desired item from the trainer.
Sam also failed to learn how to use the SGD and MS communication options during the initial intervention sessions. Therefore, for SGD and for MS (see the 20 s Time Delay & Differential Reinforcement phase of Fig.1), the procedures changed to using a longer (20 s) time delay followed by graduated guidance, as well as differ- ential reinforcement (where Sam was only given the opportunity to play if he 458 J Dev Phys Disabil (2012) 24:451–468 independently used the SGD or MS to request to play). Prompted trials were not reinforced. Because little progress was evident with these changes, a 0 s time delay was then implemented and immediate reinforcement was reintroduced (See the 0 s Time Delay and Differential Reinforcement phase of Fig.1). That is, Sam was Fig. 1Percentage of correct requests using the SGD, PE, and MS options across sessions for each participant J Dev Phys Disabil (2012) 24:451–468 459 immediately prompted to make a correct request and then given access to the tray.
However, for the MS option Sam appeared to become dependent on the trainer immediately prompting a correct response. He did not attempt to make the sign for PLAY and so for this reason, a 10 s time delay with reinforcement was reintroduced (10 s Time Delay and Differential Reinforcement phase of Fig.1).
AAC Preference AssessmentsThese assessments were undertaken to determine if participants would show a preference for using one of the three AAC options. They were undertaken after every sixth intervention session (i.e., after two sessions for each AAC option). During each preference assessment, the SGD, PE, and MS options were presented (randomly) at different positions on the table. While pointing to each option, the trainer asked the participant:Which communication option would you like to use? The SGD, PE, or MS?The child had 10 s in which to make a choice by touching one of the options. Once a choice was made, the trainer initiated one requesting opportunity with the chosen AAC option before reverting back to initiat- ing requesting opportunities with the AAC device that was scheduled to be used for the session. If the child did not choose an option within 10 s, the device preference assessment was terminated and training continued with the AAC option that was scheduled for use in that session.
Post-InterventionOnce the participant reached criterion for each AAC device, post- intervention preference assessments were introduced. These were identical to the previously described preference assessments, except that once an AAC option had been chosen, the participant continued to request preferred items using the chosen communication method for the entire 10-trial session.
Follow-upSix follow-up sessions were conducted 2 weeks following post- intervention for Joe (Session 88 of Fig.1) and Saskia (Session 85 of Fig.1).
Participants did not use either communication option during the break. Because Sam and Nicky did not complete all phases of the study due to time constraints, they did not receive any follow-up probes. Procedures for follow-up were identical to the intervention phase, except no prompting occurred and reinforcement was contingent upon a correct request. One AAC preference assessment was implemented before each follow-up session.
Inter-Observer Agreement The trainer collected data on the frequency of correct requesting, the level of prompting required during intervention for each trial, as well as which communication mode was selected during the AAC preference assessments. To assess the reliability of the trainer’s data collection, an independent observer also collected data on the frequency of requesting, level of prompting, and communication mode chosen. For each session, percentages of agreement between the independent observer and the trainer were calculated using the formula: Agreements=AgreementsþDisagreements ðÞ 100% .
Inter-observer agreement data were collected on 28 % of all sessions and ranged from 80 to 100 % with a mean of 99.2 %.
460 J Dev Phys Disabil (2012) 24:451–468 Procedural Integrity To assess procedural integrity, the independent observer used a checklist of the procedures and recorded whether or not the trainer had correctly implemented each procedural step in its proper sequence. Procedural integrity was assessed on 28 % of all sessions and ranged from 85 to 100 % correct implementation of the procedural steps with an overall mean of 99.8 %. A second independent observer collected inter- observer agreement data on 7 % of these integrity checks with 100 % agreement.
Results Figure1shows the percentage of correct requests during each session/phase of the study and for each of the three AAC modes. Figure2provides a summary of the results from the AAC preference assessments conducted during intervention and subsequent phases. In baseline (Fig.1), none of the participants ever used MS or PE to make the targeted requests. Saskia and Nicky made one and two correct SGD- based requests, respectively during baseline.
JoeWhen intervention was introduced, Joe reached the acquisition criterion for the MS option on his 15th MS training session. Similarly, when intervention was introduced, and then modified by removing the distractor symbols, Joe achieved acquisition with PE and SGD on his 16th and 17th intervention sessions, respectively.
During the post-acquisition phase, Joe chose to use the SGD (55 %) more often than PE (45 %). Once chosen, he then used the selected option (i.e., either SGD or PE) Fig. 2Results from the device preference assessment probes depicting the number of times each communication option (SGD, PE, and MS) was chosen and the number of time a device was not chosen (No Selection) across each phase of the study for each participant J Dev Phys Disabil (2012) 24:451–468 461 with 100 % proficiency. During follow-up, Joe maintained his level of correct SGD- and PE-based requests at 100 %, but his performance dropped to 20 and 50 % correct for MS. Overall, Joe received a total of 33 opportunities to choose between the SGD, PE and MS option (Fig.2) and he chose the SGD most frequently (61 %).
SamWhen intervention was introduced with Sam, he reached acquisition with PE on his 9th training session. When the intervention procedures were modified, he achieved acquisition of SGD on his 17th such session. However, even with additional procedural modifications, Sam did not achieve acquisition for MS within the time- frame of this study. Sam did not progress to the post-intervention or follow-up phases due to his failure to acquire use of the MS option. During intervention, Sam received nine AAC preference assessments (Fig.2) and he chose PE most frequently (56 %).
SaskiaSaskia achieved acquisition of PE-, MS- and SGD-based requests on her fifth, sixth, and eighth respective intervention sessions. During the post-intervention phase, Saskia always chose to use the SGD and then used it with 80 to 100 % proficiency.
During follow-up, her performance maintained at 100 % correct for the SGD, but decreased to 40 % and 0 % correct for the PE and MS modes, respectively. Overall, Saskia received 23 AAC preference assessments (Fig.2) during which she always chose the SGD.
NickyNicky achieved acquisition of SGD- and PE-based requests on her fifth and sixth respective intervention sessions. She showed an initial increase in the percent- age of correct requests using MS, but failed to achieve acquisition within the time- frame of the study and did not progress to the post-intervention or follow-up phases.
Across her four AAC preference assessments conducted during intervention (see Fig.2), she chose the SGD three times (75 %).
Discussion The present study extends previous research by van der Meer et al. (2012)by comparing acquisition of three common modes of AAC, namely SGD, PE, and MS. The findings suggest that the systematic instructional procedures used for each AAC option (Duker et al.2004) were largely effective in teaching each participant to use at least two of the three AAC options. Furthermore, a key aspect of the study was to assess preferences for one mode of communication over the others throughout the intervention process, allowing participants some degree of self-determination with respect to AAC modes (Sigafoos2006). Specifically, two participants (Joe and Saskia) reached criterion for use with each communication option and demonstrated a preference for using the SGD. The other two participants (Sam and Nicky) reached criterion for SGD and PE, but not MS. Nicky exhibited a preference for using the SGD, while Sam demonstrated a slight preference for using PE.
The findings support those of previous studies suggesting that students with DD can learn to use a SGD, PE, and MS for functional communication and that many will also indicate a preference for using a particular communication system (van der Meer 462 J Dev Phys Disabil (2012) 24:451–468 et al.2012,2011b). The findings also provide further evidence indicating that most of the children assessed to date appear to show a preference for using SGD over PE and MS (van der Meer et al.2012,2011b), although the present study appears to be the only one to date that has compared acquisition of, and preference for SGD, PE, and MS.
While all of the participants learned to use PE and SGD, Sam and Nicky failed to reach criterion for MS, even with modifications to the intervention process. This finding could suggest that MS communication is more difficult for some children to learn or that the instructional procedures used in the present study were better suited for teaching use of the SGD and PE options. With respect to the first possibility, Iacono and colleagues (Iacono and Duncum1995; Iacono et al.1993) suggested that graphic symbols, such as those used for the SGD and PE options in this study, are less demanding on children’s working memory because only recognition memory is needed, whereas MS requires the use of recall memory. This could be one reason why MS is sometimes learned at a slower rate than other AAC systems and this might also explain some of the patterns with respect to preferences for SGD and PE over MS.
Alternatively, MS might simply be a more difficult AAC system to teach because forming the signs requires more and varied physical movements than simply pointing to or handing a graphic to a partner (van der Meer et al.2012). Another possibility is that Sam and Nicky’s failure to reach criterion for MS reflected the fact that they did not prefer to use it and were therefore less motivated to participate in the MS intervention sessions, once they started to make progress with the other options. This possibility suggests that preference, or lack of preference, for an AAC option may influence motivation to learn to use that option. If this explanation has validity, it would highlight the value of assessing preferences for different AAC options during the early stages of intervention, as was attempted in the present study. However, it is unclear how early such assessments might be implemented. Pre-baseline assessments could be configured, for example, but it is unclear if participants would require some level of exposure to each option before their choices would represent valid indicators of preference.
For one participant (Joe), it appeared that discrimination of graphic symbols was difficult. Specifically, Joe did not learn to discriminate theSNACKsymbol from thePLAYsymbol, and only reached criterion for SGD and PE when the distracter (PLAY) symbol was removed. As with Sam and Nicky’s failure to reach criterion for MS, Joe’s difficulty could reflect either a problem in his discrimination learning abilities or ineffective instructional procedures. In any event, these problems in teaching Sam, Nicky, and Joe suggest there may be some value in implementing a pre-intervention assessment of children’s learning and behavioral characteristics (Light et al.1998), such as determining the level of iconicity appropriate for an individual to acquire graphic symbol and MS understanding (Koul et al.2001). From a research perspective it is important to ensure each AAC system is comparable in terms of cognitive demands so as to maintain functional equivalence in order to compare acquisition and preference between AAC systems (Schlosser2003b). It might also be important to ensure a match between the AAC system and skills being taught and the instructional strategies that are implemented to teach that system and those skills.
J Dev Phys Disabil (2012) 24:451–468 463 A limitation of the present study is that the PE system was not equivalent to the SGD and MS systems. While the SGD and MS options required only a one-step request, the former included two steps. That is, for the PE option, participants were required to not only place theI WANT,but also the correspondingSNACKorPLAY symbols, depending on whether they were requesting snacks or toys, onto the two locations provided on a separate card. This may have increased the response effort for the PE system, which in turn may have negatively influenced acquisition and preferences (Ringdahl et al.2009; Winborn-Kemmerer et al.2009). Although this did not appear to influence acquisition of the PE system in the present study, it may have diminished preference for that system. However, Sam did in fact demonstrate a preference for PE. Furthermore, due to the inherent differences in response top- ographies of SGD and PE versus MS, another potential limitation outlined by van der Meer et al. (2012) was that a MS response could be produced during SGD and PE sessions, but not vice versa, possibly influencing preferences and rapidity of acquisition.
Joe, Saskia, and Nicky appeared to show a preference for using the SGD. While this could suggest that it was easier to use than either the PE or MS option, it is also possible that the SGD required somewhat more refined motor control, which might in fact make this a more difficult option to learn. That is, activating the speech-output function of the iPod-based SGD required a level of finesse (i.e., lightly touching or tapping the icon), which has been documented to be difficult for some adolescents with DD to master (Kagohara et al.2010; van der Meer et al.2011a,2012). Despite what could be a slightly more difficult system to activate, Joe, Saskia, and Nicky showed a preference for using the SGD. While van der Meer et al. (2012) suggested that some participants may prefer AAC options that are easier to use, others may prefer SGD due to the dynamic display and speech-output features. Therefore, perhaps in addition to ease of use, it could be hypothesized that inherent features of some AAC options (e.g., speech-output) influence such preferences as suggested by Sigafoos et al. (2005). While our results suggest children showed idiosyncratic preferences for the AAC options, future research would be needed to determine variables that might influence such preferences.
Joe and Sam did not come to make any consistent choices for one communication device over the others until they had reached criteria with each system. Saskia and Nicky, in contrast, appeared to show a preference (for the SGD) before they had learned to use the communication options. These results suggest that preference for different AAC options may emerge at different times in the intervention process. In line with previous research (van der Meer et al.2012) Joe and Saskia showed better performance during follow-up with their preferred communication option. This finding suggests that preference may influence maintenance of newly acquired AAC-based requesting skills. Future research is needed to examine whether these findings might extend to interventions that focus on teaching more complex commu- nication skills, such as asking and answering questions and commenting on the environment.
It did not appear that differing reinforcement histories accounted for the children’s preferences for the different AAC options because they received the same number of sessions/reinforcements with each option during baseline and intervention. While Sam did later receive differential reinforcement schedules for the SGD and MS 464 J Dev Phys Disabil (2012) 24:451–468 options in an effort to increase his performance with these two options, he was already showing a preference for PE prior to this procedural manipulation. However, it could be that the children’s prior (pre-baseline) experiences may have influenced their preferences to some degree. Specifically, prior to this study, it appeared that while none of the children had any experience with SGDs, they reportedly had experience with one or more of the other AAC modes. Joe, Sam, and Saskia, for example, were reported to have had prior experience with manual signing and Joe and Nicky were reported to have had some experience with picture-based communication systems. Unfortunately, it is impossible to know if any of these prior experiences influenced their learning rates and choices during the AAC preference assessments that were conducted in this study. Future research could be improved by controlling for the potential bias that may arise when children enter a study with differing amounts and types of prior experiences with the to be compared AAC options. In practice, however, it may be difficult to determine the precise amount and nature of any such prior experiences given the often subjective and anecdotal nature of the information available to researchers about children’s prior AAC experiences. It is also perhaps inevitable that children with DD who have limited or no speech will be exposed to one or more AAC modes and that such exposure could influence acquisition of, and preference for, different AAC modes. We would argue that even with such difficulties and uncertainties with respect to children’s prior AAC experi- ences, it would still seem useful to assess their preference for different AAC options so as to promote greater self-determination.
In summary, the results of present study extend the findings of van der Meer et al.
(2012) by comparing acquisition of, and preference for, three commonly used AAC modes (SGD, PE, and MS) among four children with DD. The results showed that two children learned to use all three AAC modes, whereas the other two children learned to use SGD and PE, but not MS. Preference checks suggested that three of the four children appeared to prefer using the SGD, whereas the other child showed a preference for using PE. Preference appeared to influence acquisition and mainte- nance, but more research is needed to confirm any such effects.
AcknowledgmentsSupport for this research was provided from the New Zealand Government through the Marsden Fund Council, administered by the Royal Society of New Zealand; and by Victoria University of Wellington, The University of Canterbury, and The New Zealand Institute of Language, Brain & Behaviour.
Declaration of InterestsThe authors report no conflicts of interests. The authors alone are solely responsible for the content and writing of this paper.
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