I’ve studied body language for a large part of my life. It’s what attracted me to baby sign language since it too is a form of silent communication. Signing babies present some interesting cues that parents can tune into to help read their children without needing to communicate directly with them.
A signing baby will often subtly sign when they want something without doing it overtly. I would even hazard to say that signing babies don’t do it consciously either. I’ve notice my son do his sign for WATER in which he brings his index finger to his mouth without looking at me to anchor it or doing it repeatedly as he does when he’s actively seeking water (out of his consciousness). The real sign for water, by the way, is the hand in the “W” handshape tapped against the mouth several times. If I notice him doing this, I can preemptively provide him with water and he’ll gladly accept it.
I’ve noticed that he will also subtly do his sign for HELP which is hands patting against the chest (a sign not of ASL – but made easier for baby signing purposes). Usually, he only uses one hand against his chest when he’s considering asking for help, but hasn’t yet fully committed to asking.
I talk more about signing and sign enthusiasm in the online Definitive Baby Signing course and something you can use to tell if your baby is actually willing to cooperate with your requests based on how they sign. If you are interested in learning more about this strategy, you’ll find more details inside.