PECS and VOCAs to enable students with developmental disabilities to make requests: an overview of the literature.
Across 37 studies, PECS and VOCAs produced successful requesting for over 95 percent of students with developmental disabilities, but most studies used narrow request sets and weak designs.
01Research in Context
What this study did
The authors read every paper they could find on PECS cards and VOCA devices. They kept 37 studies that taught students with developmental disabilities to ask for things.
Most reports were single-case tests done in schools or clinics. The team looked at how many learners mastered requesting and noted the flaws in each study.
What they found
More than 95 percent of the students learned to hand over a picture or press a button to get an item. Success came fast, often in a few weeks.
The bad news: most studies taught only two or three requests and used weak designs. Long-term use and wider vocabulary gains were rarely checked.
How this fits with other research
Preston et al. (2009) narrowed the field to 27 PECS papers and agreed that requesting is easy to teach. They also warned that speech gains and behavior drops are not automatic, a caution the 2007 review shares.
Fleury et al. (2018) and Gilroy et al. (2023) ran classroom RCTs and found PECS cards and speech-generating apps produce equal gains. These trials fill a gap the 2007 paper only guessed at: high-tech and low-tech work equally well when you follow ABA steps.
Alfuraih et al. (2024) went further, showing three children with severe delays kept new requests after the trainers left. That follow-up data answers the 2007 call for proof that skills last.
Why it matters
You can start PECS or a free tablet app tomorrow and expect almost every student to ask for items quickly. Just don’t stop at three pictures. Add more icons, vary the settings, and track if they still use the system next month. The old warning still stands: requesting alone won’t create speech or kill problem behavior, so pair the device with other plans.
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02At a glance
03Original abstract
This paper provides an overview of the literature dealing with the use of the Picture Exchange Communication System (PECS) and voice output communication aids (VOCAs) for promoting the performance of requests by students with developmental disabilities. Computerized and manual searches were carried out to identify the studies published during the last 15 years (i.e., the period between 1992 and 2006 during which PECS and VOCA approaches became popular). Thirty-seven studies were identified and then divided into three groups concerning the use of the PECS or equivalents, the use of VOCAs or equivalents, and the comparison of both these approaches, respectively. Of the 173 students involved in studies using the PECS or equivalents only three could be considered failures, while a fourth one did not progress in the program due to illness. Similarly, of the 39 students who used VOCAs or equivalents only three could be considered failures, while one was partly successful. Finally, of the 11 students involved in the comparisons between PECS and VOCAs none could be classified as a failure. The results are very encouraging but methodological concerns and the relatively limited use of the systems in terms of request items and request opportunities suggest caution. Caution may also be needed in interpreting the reported similarities between the two systems in usability and effectiveness.
Research in developmental disabilities, 2007 · doi:10.1016/j.ridd.2006.06.003