We all have an inborn and immediate need to communicate with the world outside ourselves. Of course, the nature and extent of that need differs depending on who we are, but for most people the ability to communicate — or at least the ability to learn how to communicate — is nearly effortless. Parents chatter and coo with their newborns, but we really do not teach them how to talk. We model the behavior and they infer the myriad rules of speech almost effortlessly. What are the distinct sounds used in producing speech? (Or symbols, for deaf children) What are the words? What is the syntax? How is that modified by the tone of one’s voice or the non-verbal cues of body language and facial expressions? How can nearly all of these things be modified depending on the social situation?