Comparing communication systems for individuals with developmental disabilities: a review of single-case research studies.
No single AAC system wins—test two or three with the client and let performance and preference decide.
01Research in Context
What this study did
Gevarter et al. (2013) looked at every single-case study that compared AAC systems for people with developmental disabilities. They wanted to know if one system beats the rest.
They pulled papers that tested PECS, sign, SGDs, or mixed tools head-to-head. All studies used single-case designs so each participant served as their own control.
What they found
No system came out on top. PECS, sign, tablets, and hybrids all worked for some learners and not others.
The team says the best plan is to test two or three options with the client, then pick the one that matches their motor skills, goals, and likes.
How this fits with other research
Leaf et al. (2012) ran a meta-analysis on the same pool of aided-AAC studies and found large gains, especially with PECS and SGDs. Their positive numbers seem to clash with the "no winner" verdict, but the difference is in the question: B asked "does aided AAC work?" while Cindy asked "which aided AAC works best?"
Cox et al. (2015) zoomed in on tablet SGDs for autism and reported faster word learning than PECS or sign. Cindy’s broader view keeps this tablet edge in mind yet still urges individual trials before you lock in.
Johnson et al. (2021) added a new angle: AAC can boost speech for kids with ASD, but speech rarely overtakes AAC use. Cindy’s takeaway—match the tool to the learner—still holds; speech growth is a bonus, not a switch.
Why it matters
You can stop hunting for the "best" AAC. Run brief comparisons in your next session: three tools, three ten-minute trials, simple data sheet. Let the client’s responses, not the catalog, guide the final choice.
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02At a glance
03Original abstract
Studies that have compared different communication systems for individuals with developmental disabilities were systematically reviewed in an effort to provide information useful for clinical decision making and directions for future research. Specifically, 28 studies that compared (a) non-electronic picture systems to speech generating devices, (b) aided AAC (e.g. picture exchange systems and SGDs) to unaided AAC systems (manual sign), or (c) AAC to speech-language interventions were included in this review. Dependent variables forming the basis for comparison included: (a) effectiveness (e.g. acquisition of systems and/or rate of use), (b) efficiency or rate of skill acquisition (c) participants' preference for systems, (d) occurrence of vocalizations and problem behavior, and (e) generalization across communication partners, settings, and time (i.e. maintenance). Results suggest that clear and consistent differences between communication systems are rare, precluding definitive statements regarding a universal best approach for all people with developmental disabilities. Instead, findings of this review support the consideration of an individual's existing skills, goals and preferences as part of the process of selecting an approach to communication.
Research in developmental disabilities, 2013 · doi:10.1016/j.ridd.2013.09.017