The interactions of rational, pragmatic agents lead to efficient language structure and use

Despite their diversity, languages around the world share a consistent set of properties and distributional regularities. For example, the distribution of word frequencies, the distribution of syntactic dependency lengths, and the presence of ambigu- ity are all remarkably consistent across languages. We dis- cuss a framework for studying how these system-level proper- ties emerge from local, in-the-moment interactions of rational, pragmatic speakers and listeners. To do so, we derive a novel objective function for measuring the communicative efficiency of linguistic systems in terms of the interactions of speakers and listeners. We examine the behavior of this objective in a series of simulations focusing on the communicative func- tion of ambiguity in language. These simulations suggest that rational pragmatic agents will produce communicatively effi- cient systems and that interactions between such agents pro- vide a framework for examining efficient properties of lan- guage structure and use more broadly.