AAC and Autism: What's the Evidence?

I have been using voice output devices (VOCA) - otherwise known as speech generating devices (SDG) - for as long as they’ve been around.  And most of my caseload over the years has been full of kids on the spectrum - autism spectrum, for the uninitiated. 

And as concerned as I’ve always been with Evidence Based Practice (EBP), AAC has not always been considered EBP; if only because there weren’t sufficient research studies to make it so.

(Whoo - what a lot of acronyms in that first paragraph!)

The National Professional Development Center on Autism Spectrum Disorders compiles what it considers to be EBP for persons with ASD. To quote them, “ To be considered an evidence-based practice for individuals with ASD, efficacy must be established through peer-reviewed research in scientific journals using: 

• randomized or quasi-experimental design studies. Two high quality experimental or quasi-experimental group design studies,

• single-subject design studies. Three different investigators or research groups must have conducted five high quality single subject design studies, or

• combination of evidence. One high quality randomized or quasi-experimental group design study and three high quality single subject design studies conducted by at least three different investigators or research groups (across the group and single subject design studies).”

They have now, however, found sufficient studies that meet their criterion using AAC.  They have created a checklist for implementation that is well worth a read if you practice in AAC.

Their checklist includes some things we might consider obvious, but I’m here to tell you that I often find these things NOT happening with kids who need or use AAC.

And some of the points for practice are in line with ABA strategies, but not necessarily best practices for AAC.

So, what is a clinician to do?  Read. Consider. Balance. Interpret. And consider again.

For example, after identifying an appropriate device (well, that’s a hurdle right there), they tell teachers and clinicians to introduce the device with only a few symbols and with many blank buttons.

While using a larger grid and hiding buttons is an appropriate tactic for introducing an AAC system, we don’t want to use too few symbols.  We know that our AAC learners need sufficient vocabulary to meet their needs, as well as needing sufficient vocabulary for partners to provide Aided Language Stimulation (modeling, for short).

I have often seen the practice by ABA practitioners of moving buttons around, in order to ‘ensure that the students are really discriminating and not just memorizing location.’  

However, AAC research and practice has specifically taught us that stability of location is important; that language acquisition through motor planning is a real phenomenon.  And that moving vocabulary around only serves to make learning more difficult and to make students frustrated.

They do instruct clinicians and teachers to provide opportunities for exploration with the device, and to provide “engineered” opportunities within the student’s day that are naturally occurring.  They also remind practitioners and other partners to provide minimal prompting.  Too often I have seen well-meaning communication partners reach out and take the individual’s hand and provided Hand Over Hand guidance.

There is no mention of Aided Language Stimulation or Aided Input, which I see as a major flaw to their checklist.  They address using the least prompting necessary to get a response from the user, but do not allow for a period of modeling without requiring a response.

So, while the evidence is there for use of  AAC with kids on the Spectrum, we want to be careful of what evidence we're following.  Research, learn, and educate yourself - for the good of your clients.