One of the intriguing abilities that language users have is that of high-level reference, or the ability to refer to things or states of being that are not in the immediate realm of the speaker. This ability is often related to theory of mind, or an awareness of the other as a being like the self with individual wants and intentions. According to Chomsky, Hauser and Fitch (2002), there are six main aspects of this high-level reference system:
Theory of mind
Capacity to acquire nonlinguistic conceptual representations, such as the object/kind distinction
Referential vocal signals
Imitation as a rational, intentional system
Voluntary control over signal production as evidence of intentional communication
Number representation