Comparing acquisition, preference, maintenance, and social validity of manual sign, picture exchange, and speech-generating devices as AAC options for children with developmental disabilities

Abstract

Background: Communication deficit is a defining characteristic of children with autism spectrum disorder (ASD) and other developmental delays/disabilities (DD). In many cases the degree of communication impairment is severe. For example, approximately 25% of children diagnosed with ASD fail to develop sufficient speech to meet their everyday communication needs. In the absence of speech, these children are often taught to use augmentative and alternative communication (AAC). Three main AAC options have been taught to children with DD. These are (a) manual sign (MS), (b) picture exchange systems (PE), in which the child exchanges a picture card to communicate, and (c) speech-generating device (SGD). Debate persists in the literature as to which of these three options is best suited to address the communication intervention needs of children with DD. With the rapid developments in technology, subsequently, more high-tech devices are being introduced to the field of AAC. Studies have compared these three AAC options, but the literature has not yet compared these three options in terms of long-term maintenance of communication skills and social validity of the AAC systems.

Objective: The studies in this thesis focused on (a) comparing acquisition and maintenance of a requesting skill that was taught with each of the three AAC options (MS, PE, and SGD), (b) assessing the participant’s preference of using each of the three AAC options, and (c) assessing stakeholders’ perceptions of each AAC option in terms of perceived (a) intelligibility, (b) ease of acquisition, (c) effectiveness/acceptability, and d) preference.

Method: In Study 1, four children with DD were taught to use MS, PE, and SGD to request continuation of toy play (i.e., to request more). This experimental study was implemented using a single-subject alternating-treatment design which was divided into four phases (i.e., baseline, intervention, post-intervention, and follow-up). The effects of intervention on acquisition of the requesting response with each option were evaluated using an alternating-treatments design across participants design. Acquisition and maintenance at 12 to 18 months was compared across the three AAC options in an alternating treatments design. The participants’ preference for using each of the three AAC options was also assessed at regular intervals during the study using a choice-making paradigm. For Study 2, a non-experimental quantitative design was applied. Data were collected using an anonymous five-point Likert-scaled survey that consisted of 11 questions. 104 undergraduate students were shown a video of a person communicating with each AAC option (MS, PE, and SGD in different video clips) then asked to rate each AAC option in terms of perceived (a) intelligibility, (b) ease of acquisition, (c) effectiveness/acceptability, and (d) their preference.

Results: Study 1. With intervention, three of the four participants learned to use each of the three AAC options, but one child only learned to use the PE option. Trials to criterion across children ranged from 22 to 28 trials for the SGD, from 12 to 60 trials for PE option, and from 21 to 64 trials for MS option. For the three participants who reached criterion with all three AAC options, maintenance results were best for PE and the SGD. Preference assessments showed that participants most often chose the SGD, suggesting a preference for using that option. For Study 2, the undergraduate students, mean ratings for perceived intelligibility and effectiveness/acceptability were significantly higher for the SGD. The SGD and MS options were rated as being more preferred over PE. PE was rated significantly higher on perceived ease of acquisition.

Conclusion: The children’s high level of proficiency in using the most frequently selected AAC system (i.e., the SGD) suggest that incorporating the child’s preference for AAC system might be valuable to avoid the risk of device abandonment. Additionally, data from the social validation assessment suggests that the SGD was perceived to have greater social validity than MS and PE. The combination of these findings adds to the existing literature in supporting the use of the SGD as a promising AAC option for children with DD. Findings on acquisition rates, long-term follow-up, and preference for AAC systems extend previous research with respect to incorporating longer-term follow-up data on the child’s proficiency of and preference across AAC options. Additionally, the social validation results provide a contribution to the field of AAC intervention in relation to how the wider community perceives these three AAC options. Future research might compare several AAC systems when teaching more elaborate communication skills (e.g., social interaction) and exploring factors that might impact one’s perception of a certain AAC systems.