This chapter reviews the current research on children's awareness and theory of speech. Theory of speech, a relatively new construct largely introduced here, refers to one's beliefs and hypotheses about how speech can be used and what it can be used for. For example, speech can be used with different volumes (out loud, whisper, silent), for different purposes (communication, fantasy play, self-regulation, thought), or to different people (self, other, supernatural/spiritual figure). Several decades of research (see Berk, 1992; Winsler, Chapter 1 of this volume) support the notion that children use speech in new and different ways (from social, other-directed communication to inner, silent thought) as they progress through the early childhood years. The construct, theory of speech, has been postulated to represent one's ever-changing understanding of, or perspective on, the various types of speech used by individuals. As such, theory of speech represents one's mental understanding of how speech can be used, which might be the impetus for young children to use speech in more purposeful and regulatory ways.
Like other areas of mental understanding (e.g., theory of mind), children's understanding of what they can do with and how they can use speech (i.e., theory of speech) likely evolves through the early childhood years (Manfra & Winsler, 2006). It has been speculated (e.g., Manfra & Winsler, 2006; Winsler & Naglieri, 2003) that the developmental process of theory of speech is related to the developmental changes seen in children's actual speech use.