Sign-language exposure impacts infants as young as 5 months old

While it isn't surprising that infants and children love to look at people's movements and faces, recent research studies exactly where they look when they see someone using sign language. The research uses eye-tracking technology that offers a non-invasive and powerful tool to study cognition and language learning in pre-verbal infants.

source https://www.sciencedaily.com/releases/2021/04/210408152244.htm