Linguistics
Deaf babies babble with their hands the way hearing babies babble with sound
Hearing infants babble in rhythmic syllables as their vocal systems mature; researchers found that deaf infants exposed to sign language do the same thing with their hands, producing patterned, syllable-like 'manual babbling' distinct from ordinary baby gesture. Because it emerges on the same schedule as vocal babbling, the finding suggests babbling is a built-in stage of language development, not just imitation of speech.