A Production System Model of First Language Acquisition

A PRODUCTION SYSTEM MODEL OF FIRST LANGUAGE ACQUISITION Pat Langley Department of Psychology Carnegie-Mellon University Pittsburgh, Pennsylvania USA 15213 Abstract AMBER is a model of first language acquisition that improves its performance through a process of error recovery. The model is implemented in ACTG, an adaptive production system language. AMBER starts with the ability to say only one word at a time, but adds rules for inserting additional words in the correct order, based on comparisons between predicted and observed sentences. These insertion rules may be overly general and lead to errors of commission; in turn, these lead to more conservative rules with additional conditions. AMBER's learning mechanisms account for many of the developments observed in children's speech. Introduction The acquisition of language has been a popular topic among researchers in Artificial Intelligence. Impressive language learning programs have been developed by Siklossy [i], Hedrick [2], Anderson [3], Selfridge [4], and Berwick [5]. The generality and power of these systems vary greatly, but they share one characteristic: none of the programs provide a psychologically plausible model of children's language learning. In this paper I describe the beginnings of a more realistic model of first language acquisition. This model is called AMBER, an acronym for Acquisition Model Based on Error Recovery. As its name implies, the model simulates the incremental nature of the child's language learning process. AMBER is concerned with the production component of children's speech, since most of the reliable data relate to production rather than the understanding process. Below I summarize the major developments found during this period. After this, I present an overview of ACTG, the production system language in which the model is stated. Next I consider some assumptions about the child's linguistic knowledge at various stages during the learning process. After considering the initial and final stages of AMBER, I discuss the learning mechanisms leading to the transition process. Finally, I consider the limitations of the model and propose directions for future research. The Mayor Phenomena Children do not learn language in an all-or-none fashion. They begin their linguistic careers uttering one word at a time, and slowly evolve through a number of stages, each co~taining speech more like that of the adult than the one before. In this section I discuss the features of the three stages which AMBER attempts to explain. I discuss these stages in their order of occurrence, dealing only with the major phenomena in each case. The One-Word Stage Around the age of one year, most children begin to produce words in isolation, and continue this strategy for some months. Presumably tile child spends much of this period connecting particular words to particular concepts; once this has been done, he can produce these words under the appropriate circumstances. AMBER does not attempt to explain the word-learning process. Like Anderson's LAS [3], it assumes that links between words and concepts have already been established. Bloom [6] has examined this period in detail, with an eye to understanding the relation between the one-word …

Content truncated to 500 words