Abstract
There has been an increased interest in research evaluating the use of handheld computing technology as speech-generating devices (SGD) for children with autism. However, given the reliance on single-subject research methodology, replications of these investigations are necessary. This study presents a replication with variation, of a method for the acquisition of picture-symbol discrimination during mand training, while using the iPad® and application Proloquo2Go™ as an SGD in young children with autism. In a four-phased training procedure, three children with a diagnosis of autism acquired the ability to mand and discriminate between four picture-symbols on the screen of the device, while using the iPad Mini® as an SGD. In addition, for all three participants, the acquired repertoires maintained following the discontinuation of training. These results provide continued support for the use of handheld computing devices as SGD for children with autism.
Introduction
It is estimated that 30% of individuals with a diagnosis of autism fail to develop vocal output capabilities (Wodka, Mathy, & Kalb, 2013). As such, the use of an Augmentative and Alternative Communication (AAC) system is often incorporated into verbal behavior (or communication) training for autism intervention (Mirenda, 2003). AAC are generally divided into two broad categories: unaided and aided. Unaided AAC include gestures and manual signs and are categorized as such since they do not require any equipment. Conversely, aided AAC do require the use of equipment and included in this category are the Picture Exchange Communication System (PECS), picture-based communication systems, and speech-generating devices (SGD) or voice output communication aids (VOCA; Mirenda, 2003).
SGD or VOCA are electronic devices that use pictures, words, or other symbols that represent parts of speech such as nouns (items/activities), verbs, adjectives, and adverbs. When the symbols are selected, on the screen of the device, an audible output is produced, which is used to communicate the message. While SGD are generally effective in the acquisition of verbal behavior for individuals with autism or a related disability, it has largely been criticized for being costly and lacking durability (Shepherd, Campbell, Renzoni, & Sloan, 2009). Recent developments in technology such as handheld computing devices (i.e., the iPad®) and portable multimedia players (i.e., the iPod®), which can be adapted to function as an SGD, have led to a resurgence of the literature evaluating SGD for communication training in young children with autism. The use of such devices as an SGD allows teachers, practitioners, and other stakeholders to select a less expensive and more durable alternative to costly and non-durable traditional SGDs.
In a review of the literature, 17 studies investigating the use of handheld computing technology as an SGD were identified as published between 2007 and 2014. The collective results of the studies were generally favorable, indicating that of the 57 participants involved in such research, 53 (or 93%) acquired the targeted communication skill, while using the iPad® or iPod® as an SGD. In addition, several studies included in this review evaluated participant device preference across AAC modalities. Collectively, the results of such investigations indicated that for 92% of participants, the use of an iPad® or iPod®-based SGD was preferred to a picture-based system and/or manual sign language (Lorah, Parnell, Whitby, & Hantula, 2014). Given the heterogeneous nature of individuals with autism, these data are compelling.
For example, Lorah, Crouser, Gilroy, Tincani, and Hantula (2014) compared acquisition rates and participant device preference between a picture-based communication strategy and the iPad® as an SGD. The study involved five preschool-aged children with autism and used an alternating treatment design. The results of this investigation indicated that the SGD produced higher rates of independent manding for four of the five participants, or 80% of the participants. In addition, four of the five participants (or 80%) demonstrated a preference for the handheld SGD when offered the opportunity to communicate with either device. Two limitations of this research are clearly evident. First is the lack of a generalization data within the research design. While the participants acquired the ability to mand for items within the artificial learning environment, which the study employed, it is unclear as to whether the skill would generalize to the natural environment. Second is that the acquired mand repertoire did not include discrimination training between picture-symbols.
Achmadi et al. (2012) evaluated the acquisition of a mand repertoire in two males, aged 13 and 17 years, with a diagnosis of autism using an iPod® Touch-based SGD. In this investigation, the participants were taught using least-to-most prompting, differential reinforcement, and backward training to (a) turn on the device, (b) unlock the screen of the device, (c) navigate to the Proloquo2Go™ application, (d) locate the appropriate category folder within the application, and (e) mand for an item in a field of three picture-symbols. Results of this evaluation indicted that within the multiple baseline design, both participants acquired the ability to mand in a field of three picture-symbols and demonstrate the necessary prerequisite skills to using the device. While this investigation included more advanced operations in terms of the use of the device for communication purposes, limitations such as small sample sizes are still apparent, and the results should be considered as preliminary and interpreted with caution. Replications of these research endeavors are necessary before the use of these new technologies, as an SGD will be considered an evidence-based practice.
Only one study published to date has specifically addressed the acquisition of a discrimination repertoire in combination with the acquisition of a mand repertoire. In a five-phased discrimination training procedure, Lorah, Crouser, et al. (2014) taught four preschool-aged children with autism to discriminate between four picture-symbols while using the iPad® as an SGD for mand training. The phases involved the use of within stimulus prompting and fading, progressing from a field of one picture-symbol to a field of four picture-symbols. The first phase entailed a field of one picture-symbol with the primary function of shaping the response topography necessary for manding with the SGD. The second phase involved a field of one picture-symbol and three blank or non-referent spaces, with the primary function of refining that topography. The third phase used a field of one preferred, one neutral, and two non-referent or blank spaces and was intended to teach initial discrimination. Phase 4 presented a field of two picture-symbols of preferred stimuli, one of neutral stimuli, and one non-referent blank space. The function of Phase 4 was to continue to refine discrimination skills. The final phase was identical to baseline and contained a field of four picture-symbols (Lorah, Crouser, et al., 2014).
Results of this investigation demonstrated that the five-phased training procedure was effective in the acquisition of both a mand and a discrimination between picture-symbols repertoire. In fact, the majority of the participants progressed through the phases quickly, requiring anywhere from two (the minimum sessions necessary) to seven sessions to master a respective phase. For one participant, each phase of the five-phased training procedure only required two training sessions prior to mastery (Lorah, Crouser, et al., 2014). The results of this study indicate that the acquisition of a discrimination repertoire can be acquired in tandem with a mand repertoire using the iPad® as an SGD. However, given that the research design only entailed four participants within a single-subject research design, replications of this experimental effect are necessary.
In terms of the larger body of research, evaluating handheld computing technology as an SGD, clear limitations have emerged. First is the specific communication skills assessed. To date, the bulk of such research has solely evaluated the acquisition of a mand (i.e., request) repertoire. This leaves the effectiveness of the use of handheld computing devices as SGD for acquisition beyond the mand repertoire questionable. Second is the lack of discrimination training included in those studies evaluating these new SGDs for mand acquisition (i.e., Lorah, Parnell, et al., 2014). Finally, a large number of the research available has focused on mand acquisition using instructional procedures presented in an artificial learning environment (i.e., Kagohara et al., 2013; Lorah et al., 2013). Thus, the question of the effectiveness of naturalistic teaching methods remains largely unanswered by the current literature base.
The focus of the current study is a replication of the effects demonstrated in Lorah, Crouser, et al. (2014) with several variations. First, the current study was conducted within the natural environment, not the discrete-trial format as in the original research design. Second, the use of both within stimulus and response prompts, specifically a 5-s time delay with full-physical prompts, was used within the current investigation. This is a departure from the original research that relied on only the use of within stimulus prompting procedures. The current research modified the training procedures slightly by not incorporating the use of neutral stimuli within the discrimination training phases. This decision to not include neutral stimuli was based on the procedural difficulties in identifying truly neutral stimuli for preschool-aged children with autism. In other words, given the age of the participants, it was difficult to identify items or activates with which they would not engage with or take when offered. Finally, rather than using an iPad® Version 2 as the primary material for the SGD, the current investigation used an iPad Mini®.
Therefore, the current study evaluated (a) the use of a discrimination training procedure and (b) the use of natural environment teaching (NET) in the acquisition of a mand repertoire for three preschool-aged children with autism using the iPad Mini® and application Proloquo2Go™ as an SGD.
Method
Participants
Three preschool-aged children, one male and two females, participated in the study. Prior to the onset of the study, each of the participants had received a diagnosis of autism from a developmental pediatrician, not affiliated with the study. As shown in Table 1, the participants had a mean age of 3 years and 6 months. All three participants attended a university clinic that provided instruction based on the methodology of Applied Behavior Analysis, where they received 2 hr of instruction per day, 4 days per week. All participants had Verbal Behavior-Milestones Assessment and Placement Program (VB-MAPP; Sundberg, 2008) Barriers Assessment scores ranging from absent to limited for both manding and echoic repertoires, indicating that use of an AAC was appropriate for all three participants. In addition, all three participants scored within Level 1 for all domains of the VB-MAPP Milestones Assessment. Parent reports indicated that though the participants had exposure to the iPad® for leisure purposes, none of the participants had any training history using an SGD at the onset of the study, nor had any participant had any training history with picture-based communication and/or sign language. All three participants were recruited for this study based on attendance in the university clinic and his or her appropriateness for the project based on VB-MAPP Barriers Assessment (Sundberg, 2008) scores. Informed parental consent was obtained for all three participants prior to the onset of the study.
Participant Information.
Note. VB-MAPP = Verbal Behavior-Milestones Assessment and Placement Program.
Materials and Setting
During training, the iPad Mini® and the application Proloquo2Go™ were used as the SGD. Training sessions were conducted in the play area of the preschool classroom contained within the university center, which had a 4′ × 5.7′ oval carpet, on which sessions took place. In addition, the classroom contained two bookshelves on which a variety of toys were contained within clear plastic bins. Preferred stimuli, determined through a multiple stimulus without replacement (MSWO) preference assessment, were used during training sessions.
Dependent Measures and Definitions
Consistent with Lorah, Crouser, et al. (2014), percent of independent (i.e., manding within 5 s) and accurate (i.e., the picture-symbol selected on the screen of the device matched the item used for the training trial) manding were used as the primary dependent measures throughout all phases of the study; however, depending on the respective phase, the method used to access accuracy varied. A mand was scored as independent if the participant pressed the picture-symbol that depicted the targeted item on the screen of the iPad Mini® with enough force to evoke the synthesized output. In terms of accurate manding, during Phases 1 and 2, if the item selected (pre-trial) and the picture-symbol selected on the screen of the iPad Mini® had 1:1 correspondence, the response was scored as an independent and accurate mand. During baseline and Phases 3 and 4, correspondence checks were used to access the accuracy of independent mands and followed every independent mand. During the correspondence checks, the participant was presented with two preferred items represented on the screen of the iPad Mini®. If the picture-symbol selected on the screen of the iPad Mini® had correspondence with the preferred item selected, the independent mand was scored as accurate. Finally, percentages of independent and accurate mands were calculated across all phases. This was calculated by dividing the number of independent and accurate mands by the total opportunities to mand, with a mastery criterion of 80% independent and accurate mands across two consecutive sessions, to move to the next training phase.
General Procedures
All sessions were conducted during a scheduled 30-min “natural environment teaching” session within the classroom routine. This routine remained consistent on each instructional day, and while mand training was incorporated into each NET session, it was not the only skill targeted using this instructional session. Other skills taught in NET included matching-to-sample, imitation, and listener responding. It remained up to the instructor’s digression which skills were targeted within each respective session. Thus, the exact time during which training took place may have varied slightly from day-to-day. NET sessions occurred twice per instructional day, within the play area of the preschool classroom, described previously. A doctorate student (see “Experimenters” section), who was assigned to the participant as an instructor, conducted all of the baseline, training, and maintenance sessions. This instructor remained consistent across all phases of the research.
Stimulus preference assessment
One free operant (Roane, Vollmer, Ringdahl, & Marcus, 1998) and one-to-two MSWO preference assessments (DeLeon & Iwata, 1996) were conducted for each participant prior to baseline to determine the preferred stimuli used for training. First, a free operant preference assessment was conducted to determine which items would be tested within the MSWO. During the free operant preference assessment, the participant was presented with an array of 15 toys and activities and was able to engage with any of the items or activities while researchers collected duration data on the mean length of engagement with a particular activity. The free operant preference assessment lasted 1 hr in duration. Those activities that the participant engaged with the longest were used within the MSWO. The results of the MSWO preference assessment provided a rank of the participants’ preferences, and the four top-ranked items were used during the baseline and training procedures. For one participant, a second preference assessment was conducted midway through the study. This was done after the participant demonstrated low motivation for the initial items selected. That is, this participant no longer demonstrated engagement with, or reached for, any of the original items determined to be preferred.
Baseline
Baseline data were collected for five to 10 trials with an average of six trials per session occurring, until stable responding was determined. Consistent with Lorah, Crouser, et al. (2014), during each baseline session, an in vivo-preference assessment was conducted where the top four items from the MSWO were placed within the participant’s view, and the participant was instructed to “pick one.” The item that the participant reached for was used as the target item for the trial. Next, the iPad Mini® with picture-symbols of the four items presented on the screen was placed within three inches of the participant. If the participant independently manded, a correspondence check was used to determine the accuracy of the independent mand. If the correspondence check was accurate, the mand was scored as correct, and the participant was granted access to that item for 30 s. If the correspondence check was inaccurate, the mand was scored as inaccurate, and the participant was granted access to a randomly selected item for 30 s. A randomly selected item was used as to not inadvertently reinforce the independent, yet inaccurate response as a mand (i.e., provide 1:1 correspondence), but to provide reinforcement for independent responding. If the participant did not mand independently within 5 s, the trial was scored as incorrect/no response, and the participant was granted access to a randomly selected preferred item for 30 s. This was done to decrease the likelihood of problem behaviors associated with prolonged lack of reinforcement. The experimenter did not interact with the participant during the baseline phase other than to deliver items or activities contingent upon responding; no prompting occurred during baseline.
Discrimination training
The discrimination training procedures used were similar to those of Lorah, Crouser, et al. (2014); however, several variations from the original study were included in the current research design. First, training sessions were conducted in the natural environment, during play, rather than at a table in a discrete-trial format. In addition, the target items used for manding trials were toys and activities and did not include any edible stimuli. In terms of the discrimination training, the current investigation used only a four-phased procedure, modifying Phase 3 and not including Phase 4 within the research design. Finally, a 5-s time delay with full-physical prompts procedure was used for training purposes, rather than relying only on within stimulus prompting and fading for instructional purposes.
All training trials began with an in-vivo preference assessment, during which the participant was presented with the top four items from the MSWO and he or she was instructed to “pick one.” The item that the participant reached for was used as the target item for the trial. That item was kept in view and out of reach during the trial until either the participant independently manded for the item or a 5-s latency for responding passed. The iPad Mini®, with the screen arranged for the specific trial (described below), was then presented immediately within 3″ of the participant. If no mand occurred after a 5-s time delay, or if the participant made an error in the accuracy of the mand, a full-physical prompt was used to evoke correct responding, and the participant was granted 30 s of access to the item for which he or she was prompted to mand for. Finally, if the participant manded independently and accurately for the item, the trial was scored as correct, and he or she was granted 30 s of access to that item. Trials proceeded in this manner until five to 10 trials were complete, which comprised one training session.
Phase 1
During Phase 1, the screen of the iPad Mini® was arranged to contain one picture-symbol, which was the item selected during the in-vivo preference assessment. This picture-symbol filled the entire screen of the device. An independent mand was scored if the participant pressed the picture-symbol on the screen of the device with enough force to evoke the audible output. If the participant did not respond within 5 s, the response was scored as incorrect, and the experimenter used a full-physical prompt to evoke correct responding. When the participant reached a criterion of 80% independent and accurate responding across two consecutive sessions, he or she proceeded to Phase 2.
Phase 2
During Phase 2, the screen of the iPad Mini® was arranged to contain one picture-symbol, which was the item selected during the in-vivo preference assessment, and three non-referent or blank symbols. Collectively, these four symbols filled the entire screen of the device. If the participant selected the picture-symbol on the screen with enough force to evoke the audible output, the trial was scored as independent and accurate, and the participant was granted access to the item requested for 30 s. If the participant selected a non-referent/blank space or if the participant did not respond within 5 s, no digitized output was evoked, the trial was scored as inaccurate, and the experimenter used a full-physical prompt to evoke correct responding. Following each trial, the location of the picture-symbols on the screen was changed so that no symbol appeared in the same location for two trials in a row. When the participant reached a criterion of 80% independent and accurate responding across two consecutive sessions, he or she proceeded to Phase 3.
Phase 3
During Phase 3, the screen of the iPad Mini® was arranged to contain two picture-symbols of preferred items/activities and two non-referent/blank symbols. Collectively, these four symbols filled the entire screen of the device. The target item was the item selected during the in-vivo preference assessment, and correspondence checks were used to assess accuracy of mands. If the participant selected a picture-symbol with enough force to evoke the digitized output and there was correspondence with that item during the correspondence check, the trial was scored as independent and accurate. If the participant selected a non-referent/blank space, did not respond, or did not demonstrate correspondence, the trial was scored as inaccurate, and the experimenter used a full-physical prompt to evoke correct responding. Following each trial, the location of the picture-symbols, on the screen, were changed so that no symbol appeared in the same location two trials in a row. When the participant reached a criterion of 80% independent and accurate responding across two consecutive sessions, he or she proceeded to Phase 4.
Phase 4
Phase 4 was identical to baseline, and was used to assess mastery of basic picture-symbol discrimination in a field containing four picture-symbols representing four preferred stimuli. Trials began with an in-vivo preference assessment, with the items selected being either the target item or the distractor item for correspondence checks. The screen of the iPad Mini® was arranged to contain the top four items selected during the MSWO. Correspondence checks were used to assess the accuracy of responding during this phase and were conducted after every independent mand. If the participant selected a picture-symbol with enough force to evoke the digitized output and there was correspondence with that item during the correspondence check, the trial was scored as independent and accurate. If the participant selected a picture-symbol with enough force to evoke the digitized output, but there was no correspondence during the correspondence check, the trial was scored as independent and inaccurate. If the participant did not respond within the 5-s latency, the trial was scored as incorrect. For all trials scored as inaccurate and/or incorrect, the experimenter used a full-physical prompt to evoke correct responding. Following each trial, the location of the picture-symbols on the screen was changed so that no symbol appeared in the same location two trials in a row. Once the participant met a mastery criterion for this phase, training was considered complete. Once all four participants reached mastery criterion, maintenance probes were collected.
Maintenance
A minimum of two maintenance probes were collected for each participant following the completion of training by all four participants. Maintenance sessions were identical to those used for baseline.
Interobserver Agreement (IOA) and Procedural Fidelity
IOA was assessed during 36% of all sessions including baseline, training, and maintenance and across all three participants. All IOA sessions occurred within the natural setting and were conducted by the primary investigator. IOA data were calculated by taking the number of agreements and dividing that by the number of agreements and disagreements and multiplying by 100. The overall agreement across all sessions and participants was 99%. In addition, procedural fidelity checklists were used to ensure that the training procedures were followed to the specifications of the primary investigator. Procedural fidelity checklists were completed by the experimenter following every training session and indicated 100% fidelity.
Experimental Design
A multiple baseline across participants, within a changing criterion design, was used (Gast, 2010). Following baseline data collection, participants were exposed to the five-phased discrimination training procedure, in a staggered format. This design choice was consistent with the Lorah, Crouser, et al. (2014) investigation.
Experimenters
The experimenters were three doctorate students in Applied Behavior Analysis at the university where the center was located. Each had extensive experience in behavior analytic treatment for autism. Prior to the start of the study, the primary investigator, an assistant professor at the same university, reviewed the procedures with the experimenters and each experimenter was required to demonstrate fidelity with the experimental procedures. In addition, the primary investigator was present during 70% of training trials for each of the participants.
Results
As depicted in Figure 1, visual analysis of all three participants’ data indicates a degree of experimental effect. It is clear from the stable baseline responding across all three participants and relative change in responding following the introduction of the training procedure that the implementation of the training procedure was responsible for the changes in responding. For all three participants, there was relatively immediate acquisition of the discrimination and manding repertoire following the implementation of the four-phased training procedure. Regarding the magnitude and trend of the data, there are clear and consistent demonstrations of experimental effect. In terms of percentage of non-overlapping data, when comparing responding from baseline with Phase 4, there is 100% non-overlapping data for all three participants, indicating a high degree of experimental effect. Finally, for all three participants, the acquired discriminative manding repertoire maintained following the discontinuation of training.
Percentage of independent and accurate manding.
Ellen
As depicted in Figure 1, Ellen never independently manded across the three baseline data collection points. Ellen progressed through each of the four phases with the minimum necessary training sessions of two. She averaged 100% responding during all four phases. Seven maintenance sessions were conducted with Ellen, during which she averaged 99% (range = 90%–100%) independent and accurate manding.
Tyler
As depicted in Figure 1, Tyler never independently manded across the five baseline data collection points. He required five training sessions for Phase 1 and averaged 58% (range = 10%–100%) accurate manding. He required three training sessions for Phase 2 and averaged 90% (range = 70%–100%) accurate manding. For Phase 3, Tyler required four training sessions and averaged 70% (range = 50%–100%) accurate manding. He required three training sessions for Phase 4 and averaged 70% (range = 20%–100%) accurate manding. With the exception of one variable (Session 15) data point, there are clear upward trends indicted across all four phases. Three maintenance sessions were conducted with Tyler, where he averaged 100% accurate manding.
Emma
As depicted in Figure 1, Emma averaged 2% accurate manding (range = 0%–20%) during baseline. She required four training sessions to reach criteria for Phase 1, averaging 58% (range = 20%–90%) accurate manding. For Phase 2, Emma required five training sessions and averaged 64% (range = 20%–100%) accurate manding. Two training sessions were required for mastery of Phases 3 and 4, where Emma demonstrated 90% and 80% accurate manding, respectively. With the exception of one variable (Session 16) data point, there are clear upward trends indicted across all four phases. Two maintenance sessions were conducted with Emma where she averaged 90% (range = 80%–100% accurate manding).
Discussion
The focus of this study was to replicate the results of the Lorah, Crouser, et al. (2014) investigation into a discrimination training procedure. Although this study contained several variations from the original research, the results were consistent, demonstrating that a discrimination repertoire can be acquired in tandem with a mand repertoire using the iPad® or in this case, the iPad Mini®, as an SGD in young children with autism. In addition, this study demonstrated that the training conducted within the natural environment or play environment is effective for the acquisition of such repertoires, providing an important extension to the literature on this topic.
As was the case in the Lorah, Crouser, et al. (2014) investigation, one interesting finding was the speed at which participants acquired the ability to discriminate between picture-symbols. In the current study, one participant (Ellen) progressed through each phase after only two training sessions, which is the minimum number required for mastery. Taken together, an average of four sessions were required to master Phases 1 and 2 of the training procedures; an average of three sessions were required to master Phase 2; and an average of only two training sessions (the minimum required number) were necessary to master Phase 4. Interestingly, the final phase, the phase that required the most sophisticated discrimination repertoire, was acquired more immediately for all three participants. This could potentially indicate that additional picture-symbols included in larger field sizes could be mastered with increased immediacy.
An average of 12 sessions was required for each participant to progress through the four-phased training procedure, again with eight sessions being the minimum requirement. In the original research, an average of 14.5 sessions was required for a participant to progress through a five-phased training procedure. It is not surprising that the participants mastered the current protocol more quickly, given that it was one-phase shorter. This suggests that perhaps the use of neutral stimuli as distractor picture-symbols, as was included in the original Lorah, Crouser, et al. (2014) investigation, is not a necessary phase in the acquisition of a discrimination repertoire. Furthermore, not including this phase allowed participants to progress through the training more quickly.
Finally, the current research used both a within stimulus prompting strategy (i.e., the progressively more complex field) and the use of a 5-s time delay full-physical prompting strategy. This is a departure from Lorah, Crouser, et al. (2014), which relied only on the use of within stimulus prompting. The decision to use a time delay with full-physical prompts within the current research design was done so to evaluate its use in terms of the immediacy of acquisition. That is, it was expected that by combining stimulus and response prompting, acquisition would occur at a faster rate. However, given that there was no significant change in the immediacy at which this skill was acquired from the Lorah, Crouser, et al. (2014) investigation, it is evident that both methods are effective in the acquisition of a discriminative mand repertoire using the iPad Mini® as an SGD.
Limitations of the current investigation include the lack of the inclusion of a generalization phase of the research design. This study did not evaluate whether the acquired repertoire would be demonstrated outside of the environment where training took place. Future studies should evaluate the generative effects of the acquired repertoire. In addition, the current investigation did not include a measure of social validity, which is another limitation of the current research and consideration for future research endeavors. An additional limitation of the current investigation and an important consideration for future investigations would be to evaluate training in larger field sizes. The current investigation remained consistent with Lorah, Crouser, et al. (2014) in that only a field of four picture-symbols was used. Given how quickly participants acquired a field of four picture-symbols, including larger field sizes could be included in future inquiries into this topic.
A final limitation is the mastery criterion that was used for progression through the four phases of the discrimination training procedure. Although it is acknowledged that three-to-five data points are necessary for the detection of trend and stability, this study used a criteria of two sessions at or above 80% accurate and independent manding, as that is the criterion used within the Lorah, Crouser, et al. (2014) investigation. Thus, future investigations should seek to evaluate training across a minimum of three data points as it provides a better indication of experimental effect.
Despite these limitations, the current investigation was successful at replicating the work of Lorah, Crouser, et al. (2014). The current investigation took several variations from the original research; however, the current investigation was still successful at demonstrating a mand repertoire can be acquired in tandem with a discrimination repertoire, using the iPad Mini® as an SGD, in young children with autism.
Footnotes
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.