Augmentative and alternative communication interventions for persons with developmental disabilities: narrative review of comparative single-subject experimental studies.

The authors read 79 single-subject experiments that compared AAC systems.

They looked at aided (picture boards, tablets), unaided (sign language), and mixed systems.

All studies involved people with developmental disabilities who had little or no speech.

The review does not give one winner.

Instead it gives a big table that lists each study, the AAC type tested, and the outcome.

You can scan the table to see which systems worked for which learners.

Gentry et al. (1980) is one of the 79 studies in the table. It showed total communication beat sign-alone for one mute autistic child.

Hong et al. (2017) later pooled tablet AAC studies and found medium-to-large effects. This meta-analysis covers the same ground but gives stronger numbers.

Meuris et al. (2014) offers a quick narrative test you can use to check if sign plus speech is helping adults with ID.

These newer papers do not clash with the 2006 review; they simply update the evidence base.

Print the evidence table and keep it in your clipboard. When you pick an AAC system for a new nonverbal client, scan the rows that match that learner’s age and diagnosis. If the table shows three or more successful cases with the same system, start there.