Many areas of language-related research - language processing, linguistic semantics/pragmatics, speech understanding and synthesis, and psychological theories of attention - have shown an increasing need to describe and understand aspects of discourse anaphora in relation to both processing complexity and the global structure of discourse. A major problem in this area is the large gap between existing theories and accounts of actual phenomena in naturally occurring discourse. This work is an account of one aspect of discourse, local discourse structure, that makes specific claims about both processing complexity and discourse anaphora. The book focuses on Centering Theory's ability to account for data from naturally occurring discourse in several languages. The contributors test empirically several claims of Centering Theory, propose extensions to and refinements of Centering, and show how Centering can be integrated with other aspects of discourse structure and processing.

This book constitutes the refereed proceedings of the 12th International Conference on Intelligent Virtual Agents, IVA 2012, held in Santa Cruz, CA, USA, in September 2012. The 17 revised full papers presented together with 31 short papers and 18 poster papers were carefully reviewed and selected from numerous submissions. The papers are organized in topical sections on IVAs on learning environments; emotion and personality; evaluation and empirical studies; multimodal perception and expression; narrative and interactive applications; social interaction; authoring and tools; conceptual frameworks.