jamie tips a story about MIT cognitive scientist Deb Roy, who started a project five years ago, upon bringing his newborn son home from the hospital, to record his family's movement and speech inside their house. Since then, Roy has used various techniques to analyze and distill the 200 terabytes of raw data into useful and interesting visualizations. "For example, Roy was able to track the length of every sentence spoken to the child in which a particular word — like 'water' — was included. Right around the time the child started to say the word, what Roy calls the 'word birth,' something remarkable happened. 'Caregiver speech dipped to a minimum and slowly ascended back out in complexity.' In other words, when mom and dad and nanny first hear a child speaking a word, they unconsciously stress it by repeating it back to him all by itself or in very short sentences. Then as he gets the word, the sentences lengthen again. The infant shapes the caregivers’ behavior, the better to learn." Roy also compiled videos showing each time his son used certain words over a period of many months, clearly illustrating how those parts of the child's linguistic capabilities evolved over time.