I have seen deaf children develop increased cognitive skills, improved communication, and better social interactions.
Deaf children who sign typically outperform their hearing peers in intelligence tests. This is because learning a visual language helps to develop their spatial reasoning skills. In fact, research has shown that using sign language to communicate stimulates the same parts of the brain as spoken languages do.
Sign language can also help improve communication between deaf and hearing people. By learning to communicate using signs, deaf people can share information with others in a way that is direct and easily understood. Signing also allows deaf people to participate more fully in conversations and social activities.