After food and sleep, what a toddler wants most is to be understood. After centuries of believing that infants were born as blank slates, developmental psychologists have discovered, with the help of brain scans, that infant’s brains are actively seeking attention to communicate sophisticated thoughts to meaningful adults. They just need someone to give them the words. Months-old babies can say “more,” “gone,” “uh-oh,” and “what’s that?” Parents, who are listening for words l