A functional analysis of non-vocal verbal behavior of a young child with autism.
You can run a four-condition FA on sign language and read the mand, tact, and imitation curves just like with spoken words.
01Research in Context
What this study did
The team ran a four-condition functional analysis on a preschooler with autism. The child used American Sign Language instead of speech.
Each five-minute session tested a different purpose: mand (sign to get items), tact (sign to name items), imitation (copy adult sign), or control (no consequence). The order switched fast so results stayed clean.
What they found
The child signed most when the sign produced toys or snacks. Signing dropped when the adult only named the item and vanished when nothing happened.
The pattern proved the sign worked like a spoken word. It had the same three verbal operants: mand, tact, and imitation.
How this fits with other research
Bonvillian et al. (1981) first showed that many nonspeaking children with autism learn sign. Jarmolowicz et al. (2008) move that idea forward by testing why the child signs, not just whether he can.
Van der Molen et al. (2010) extend the finding. After they taught sign mands with a short wait and a spoken prompt, the same kids began to vocalize. The 2008 FA explains why the mand condition is the best place to start.
Strohmeier et al. (2023) use the same FA logic on repetitive speech. Both papers confirm that any topography—signs or odd chatter—can be pinned to its operant function.
Why it matters
If a client uses sign, picture, or device, you can still run a classic FA. Map the mand, tact, and imitation curves in one brief session. Then build treatment on the strongest function, usually mand. This saves hours of guesswork and keeps early therapy focused on requests—the response most likely to bring speech or sign growth.
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02At a glance
03Original abstract
The functions of an American Sign Language response were experimentally evaluated with a young boy diagnosed with autism. A functional analysis procedure based on that reported by Lerman et al. (2005) was used to evaluate whether the target sign response would occur under mand, tact, mimetic, or control conditions. The target sign was observed most often in the mand and mimetic test conditions, very seldom in the tact test condition, and never in the control condition. These results support those reported by Lerman et al. and extend previous research by evaluating a non-vocal verbal response using a brief multi-element arrangement with a single control condition. The implications for language assessment and suggestions for future research are discussed.
The Analysis of verbal behavior, 2008 · doi:10.1007/BF03393057