Increasing the vocal responses of children with autism and developmental disabilities using manual sign mand training and prompt delay.

The team worked with children who had autism or developmental delays and did not speak.

They taught each child to ask for toys using sign language.

While the child signed, the adult waited three to five seconds and also said the word out loud.

The study used a multiple-baseline design across children to show the effect.

Every child began to say the word after they signed.

Vocal sounds showed up only after the sign-plus-delay routine started.

No child spoke before the training began.

Chambers et al. (2003) saw the opposite result with adults: P.E.C.S. beat sign language for speed and generalization.

The difference makes sense—adults with severe ID may have weaker fine-motor memory, while young kids with autism often echo what they see and hear.

Valentino et al. (2019) give a quick rule: if the child can already copy two-syllable sounds, vocal mand training is worth it; if not, start with pictures.

Drasgow et al. (2016) add a safety tip—teach at least two ways to ask so the child can switch if the first way fails.

You can use sign language as a bridge to speech instead of waiting for vocals to appear.

Pair every sign with a spoken word and a short pause; the pause gives the child room to try the word.

Check the child’s vocal imitation first—if two-syllable copying is missing, picture exchange may be faster.

Either way, teach two mand forms early so the learner always has a working voice.