It has become quite popular to teach babies to speak in American sign before they can speak orally. I’ve looked at several website promoting this activity, and none of them explain one thing. The process of teaching sign language to children is to repeat the word while showing the baby how to shape the sign with their hands.
The question naturally arises, if babies do not know a word, how can they recognize it and associate it with a sign?
Early in his distinguished career, Noam Chomsky wrote that comprehension is just the reverse of speaking. He never went into detail, probably because he soon discovered it isn’t true.
Comprehension far outpaces speech production. Even in adults, we recognize far more words than we can use in speech. Babies learn to comprehend far sooner than they can train the musculature of their speech tracts. The problem with tot speak is that they are unable to pronounce the large store of vocabulary that they can recognize.
I’m reminded of a funny story told by a famous semanticist. Her husband was sitting in the living room reading the paper when their 2-year-old daughter came in and said, “I want tootie”. Her father replied, “When I finish reading the paper, I will get you a ‘tootie’”. The child angrily retorted, “No! No want ‘tootie’. Want tootie!” She got her father’s attention, for he asked, “Do you want a cookie or not?” To which the child replied, “Yes. Tootie. I want tootie.”
The point of this story is that the little girl could perfectly well understand the word cookie and thought she was pronouncing it correctly. She could even tell her father was mispronouncing . But her vocal organs lagged behind her ears in development and she didn’t realize that she was mispronouncing it.