State of the Art in AAC: A Systematic Review and Taxonomy
Humphrey Curtis, Timothy Neate, Carlota Vazquez Gonzalez · 2022 · Proceedings of the 24th International ACM SIGACCESS Conference on Computers and Accessibility (ASSETS '22) · doi:10.1145/3517428.3544810
Summary
This paper presents the first systematic review and taxonomy of high-tech augmentative and alternative communication (AAC) devices and interventions within the ACM literature. The authors analyzed 562 articles from the ACM Digital Library and SCOPUS databases spanning 43 years of research (1978-2021), following PRISMA 2021 guidelines. The review addresses three research questions: what are the current taxonomy and dominant characteristics of high-tech AAC, what research methods are used to study these devices, and who do AAC devices and interventions focus on. The authors developed a codebook with 16 categories and 85 subcodes through iterative qualitative coding, with inter-rater reliability calculated using Fleiss's Kappa. The taxonomy covers interaction inputs and outputs, scalar attributes, interface layouts, communication scenarios and partners, communication models and types, and device characteristics. The paper also cross-analyzes its findings against the Mack et al. survey of accessibility research to contextualize AAC within the broader accessibility field. The motivation stems from the persistent problem of high AAC device abandonment — devices are often unreliable, slow, culturally inappropriate, stigmatizing, expensive, and difficult to program, making them challenging for users, caregivers, and specialists alike.
Key findings
The review reveals several significant patterns in AAC research. Mechanical input (38.4%) and tactile input (32.7%) dominate, while camera, gestural, verbal, and contextual inputs remain underexplored despite holding promise for future innovation. Audio output (62.8%) is the most common, with visual output at 27.9%. High-tech AAC overwhelmingly focuses on verbal communication (92.3%) using a linear communication model (87.4%), meaning most devices support only one-way message construction with limited feedback — only 1.4% of research explores non-verbal communication and just 1.4% supports transactional communication. Devices are primarily designed for use with professionals (56%) and family/friends (39.3%), with group communication (6.9%) and virtual settings (6.6%) largely neglected. Text (57.3%) and symbols (39.7%) dominate interface layouts, while visual scene displays and animation remain underexplored. Customizability (55.2%) and automation (46.6%) are the most common scalar attributes. Methodologically, 73% of contributions are empirical with controlled experiments (45.3%) favored, but zero randomized controlled trials were found. Participatory design adoption is low (4.8%). Research communities of focus are dominated by the broad "Other" category (39%) and motor impairments (32.4%), while blind/low vision (2%), deaf/hard of hearing (2.5%), and older adults (0.7%) are severely underrepresented. Median participant counts are low (N=5) with high standard deviations, and proxies are used in 20.7% of studies.
Relevance
This comprehensive taxonomy is an essential reference for anyone working in AAC design and research. The finding that AAC overwhelmingly supports only linear, verbal communication reveals a fundamental limitation — real human communication is multimodal, interactive, and contextual, yet most AAC devices constrain users to slow, one-directional text or symbol selection. The absence of randomized controlled trials and the low adoption of participatory design methods are concerning, particularly given that AAC users with complex communication needs are precisely the population whose perspectives are most critical to include in the design process. For practitioners, the inventory of 19 key devices and technologies provides a practical landscape of available tools. The paper's call to move beyond customization and automation toward expressivity, adaptiveness, and non-verbal communication support charts important future directions. Organizations selecting AAC solutions should be aware that most research has been conducted in lab or clinical settings rather than the real-world environments where devices will actually be used.
Tags: augmentative and alternative communication · AAC · systematic review · taxonomy · complex communication needs · speech generating devices · assistive technology · participatory design