Co-Principal Investigator: Vannest, Kimberly; Pustejovsky, James

Purpose: The purpose of this project is to conduct a comprehensive meta-analysis to determine whether augmentative and alternative communication (AAC) is associated with improved outcomes (e.g., behavior and communication) for individuals with intellectual/developmental disabilities (IDD). Although AAC is widely used in educational settings, it is unclear for whom and under what conditions it is most effective. This project aims to address this gap by conducting a meta-analysis to explore relationships between AAC and education outcomes for individuals with IDD. The project will also examine whether relationships differ based on the type of instructional protocols implemented (e.g., Picture Exchange Communication System, functional communication training, and other behavioral techniques), implementers (e.g., educator, paraprofessional, parent/caregiver) and settings (e.g., home, classroom, clinic). Ultimately, the results will provide important information to researchers on the need for the development of AAC interventions and to practitioners and caregivers on how best to individualize AAC interventions.

Project Activities: The research team will start by identifying articles focused on the use of AAC for individuals with IDD. For articles that meet inclusion criteria (see below), the research team will evaluate the quality of research designs and evidence to determine whether AAC can be considered an evidence-based practice. Last, the research team will conduct several meta-analyses to determine the associations between AAC and social/communicative and behavioral outcomes for students with IDD and whether associations differ by type of instructional protocol, implementer, and educational setting.

Products:  The products of this study will include results from a meta-analysis describing relationships between AAC and education outcomes for individuals with IDD and potential differences in these relationships based on the instructional protocol, implementer, and educational setting. Products will also include peer-reviewed publications and presentations.

Structured Abstract

Setting: The research articles reviewed in this meta-analysis will include studies conducted in natural settings, including the home, classroom, community, place of employment, or clinic.

Sample: The research articles reviewed in the meta-analysis may include individuals ages 0-22 with IDD, including autism spectrum disorder (ASD), intellectual disability (ID), other developmental disabilities (DD), and complex communication needs (cannot communicate via age-expected speech).

Malleable Factors: The malleable factors under investigation are variables related to instruction in AAC (i.e., type of instructional protocols implemented, implementers, and settings). AAC includes any means of communication intended to replace or supplement communication, particularly speech, in individuals with complex communication needs.

Research Design and Methods: Researchers will use meta-analysis, a method of quantitative research synthesis that uses prior study results as the unit of observation. First they will conduct a literature search that focuses on the use of AAC among individuals with disabilities. To identify studies, researchers will: (1) search electronic databases (i.e., Academic Search Complete, ERIC, PsycINFO, Conference Proceedings Citation Index — Social Science & Humanities [Web of Science], and Proquest Dissertations & Theses Global); (2) search reference lists of identified articles and systematic reviews of AAC; and (3) contact first authors of identified articles and those who regularly publish single-case experimental design research related to ASD/IDD and AAC. Studies will be included if they (1) include at least one participant with an IDD, ASD, ID, or other DD; (2) use a single-case experimental design or between-groups design; (3) report the results of an AAC intervention and for group design studies, include a comparison to a no-treatment or business-as-usual control condition; (4) include social-communicative and/or behavior outcomes; (5) involve implementation of AAC in natural settings, including home, classroom, community, employment, or clinic; and (f) are in English. Published and unpublished manuscripts will be included in the review. Second, for studies that meet inclusion criteria, they will evaluate the quality of the designs and evidence based on the What Works Clearinghouse standards, the Council for Exceptional Children's standards, and other sources. Third, they will determine if the use of AAC among individuals with IDD can be considered an evidence-based practice. Fourth, they will conduct meta-analyses to examine associations between AAC and outcomes for individuals with IDD and whether associations differ by instructional protocol, implementers, and setting.

Control Condition:  Due to the nature of the research design, there is no control condition.

Key Measures: The outcomes in this meta-analysis are the effect sizes for each eligible study. For single-case experimental design studies, the following three effect sizes will be calculated using available data: response ratio, Tau-U index, and between-case standardized mean difference. For group design studies, standardized mean difference effect sizes and associated sampling variances will be calculated from reported summary statistics.

Data Analytic Strategy: The researchers will code eligible articles for methodological issues (related to population and sample, design quality, measurement quality, data quality and missing data, and statistical method) and malleable and moderating factors, including instructional protocol, implementer, context/setting, and participant characteristics (i.e., disability, age, and intellectual and communicative functioning levels). Effect sizes will be calculated for each eligible study. Mixed-effects meta-regression models with robust variance estimation will be used to investigate the magnitude of effects of AAC interventions and factors that moderate these effects. Separate analyses will be conducted for each of the three single-case design effect sizes and for any group design effect sizes. Researchers will use multilevel modeling for the response ratio and Tau-U effect sizes and typical mixed-effects meta-regression models for the other effect sizes.