Second Language Vocabulary Acquisition: A Lexical Input Processing Approach

Abstract: This article discusses the importance of vocabulary in second language acquisition (SLA), presents an overview of major strands of research on vocabulary acquisition, and discusses five principles for effective second language (L2) vocabulary instruction based on research findings on lexical input processing. These principles emphasize presentation of new words as input, allocation of limited processing resources during vocabulary acquisition, distinct components of vocabulary knowledge (e.g., form, meaning, mapping), and appropriate types of instruction for different stages of development. Empirical support is included. Introduction The past two decades of research on second language acquisition (SLA) and second language (L2) methodology have been marked by increased interest in L2 vocabulary acquisition and greater acknowledgment of the importance of vocabulary acquisition as a central component of SLA. Research on L2 vocabulary has addressed a wide variety of issues, ranging from incidental vocabulary learning, the nature of the bilingual lexicon, and how L2 words are processed as input. Along with developments in L2 vocabulary research comes the need to synthesize and summarize pedagogical implications of this research so that they become more readily available to L2 instructors who are interested in effective L2 vocabulary instruction in the classroom. In this light, the primary purpose of this article is to present and discuss a series of basic principles regarding L2 vocabulary acquisition based on a synthesis of current research findings on L2 vocabulary acquisition and how learners process new L2 words as input. The principles are intended to serve as a guide for L2 instructors. In order to frame the discussion of the principles within a larger context, the first two sections of the article consider the importance of vocabulary acquisition in SLA and the wide range of different areas of research related to L2 vocabulary acquisition. The first section considers why vocabulary acquisition is central to SLA, touching upon the role of vocabulary knowledge in communication, student perceptions about vocabulary, and the connection between vocabulary and grammatical knowledge. The second section of the article presents an overview of major areas of research related to L2 vocabulary acquisition. These include incidental vocabulary learning, lexical requirements for comprehension, text manipulation and input enhancement, vocabulary learning strategies, combining indirect and direct instruction, methods of direct instruction, word-based determinants of vocabulary learning, the bilingual mental lexicon, receptive versus productive vocabulary knowledge, and lexical input processing. The overview of each of these areas includes examples of some research findings. Finally, the last section of the article discusses five principles for effective L2 vocabulary instruction. These principles highlight implications of research on L2 vocabulary acquisition with emphasis on lexical input processing. The Importance of Vocabulary Acquisition in SLA Successful SLA involves development of multiple linguistic subsystems-phonetics and phonology, morphology, vocabulary, grammar, and pragmatics. Nevertheless, in the history of SLA as a field and in L2 instruction, grammar has been a primary focus of attention (see Richards, 1976; Zimmerman, 1997). Without denying the importance of grammar, this section considers three points that underline the importance of vocabulary in SLA: (1) the relationship between vocabulary and the ability to communicate; (2) student perceptions about the relative importance of vocabulary; and (3) the critical role of vocabulary knowledge in the development of grammatical competence. To begin, with regard to vocabulary and communication, lack of grammatical knowledge sometimes impedes successful transmission of meaning, however, absence of vocabulary often impedes the transmission of meaning completely (Wilkins, 1972). …