Language evolution from a simulation perspective: On the coevolution of compositionality and regularity.

摘要

The thesis presents a multi-agent computational model to explore a key question in language emergence, i.e., whether syntactic abilities result from innate, species-specific competences, or they evolve from domain-general abilities through gradual adaptations. The model simulates a process of coevolutionary emergence of two linguistic universals (compositionality, in the form of lexical items; and regularity, in the form of constitute word orders) in human language, i.e., the acquisition and conventionalization of these features coevolve during the transition from a holistic signaling system to a compositional language. It also traces a "bottom-up" process of syntactic development, i.e., agents, by reiterating local orders between two lexical items, can gradually form global order(s) to regulate multiple lexical items in sentences. These results suggest that compositionality, regularity, and correlated linguistic abilities could have emerged as a result of some domain-general abilities, such as pattern extraction and sequential learning.; In addition to individual learning mechanisms, the thesis further explores the effects of cultural transmission, social and semantic structures on language evolution. First, it simulates some major forms of cultural transmission, and discusses the role of conventionalization during horizontal transmission in language evolution. Second, it traces the emergence and maintenance of language in some stable social structures, and explores the role of popular agents in language evolution, the relationship between mutual understanding and social hierarchy, and the effect of exoteric communications on the convergence of communal languages. Finally, it studies language maintenance given different semantic spaces, and illustrates that the semantic structure may cause bias in the constituent word order, which can help to predict the word order bias in human languages. These explorations examine the role of self-organization in language evolution, provide some reconsideration on the bottleneck effect during cultural transmission, and shed light on the study of the social structure effects on language evolution.