the processing of sound. it raised questions, how is it possible? why didn't that tissue in a deaf person become atrophied? and our conclusions were there was a mistake, that science had misunderstood the function of this tissue. >> the research also showed early exposure to a visual language, like american sign language did not undermine a baby's ability to learn spoken language. in fact, pettito says, it's just the opposite. >> early exposure to sign language is by far the most healthy thing we can do for the human brain. because the brain, the brain doesn't care about modality. it doesn't care if you give it the hands or the tongue. >> no matter how it's expressed, communication is really what language is all about.