Abstract Acknowledgements List of Tables List of Figures List of Abbreviations INTRODUCTION 1 Need for the study 2 Aims of the study 3 Overview of the dissertation Part Ⅰ LITERATURE REVIEW Chapter One Related Theoretical Studies 1.1 Definition of key terms 1. 1.1 Output 1.1.2 Task 1.1.3 Noticing 1.1.4 Lexical knowledge and acquisition 1.2 Theoretical issues 1.2.1 The Output Hypothesis 1.2.2 Noticing in SLA 1.2.3 Summary Chapter Two Empirical Studies on the Noticing Function of Output 2.1 The effects of output on the noticing of input 2.2 The effects of output on the acquisition of formal aspects of input 2.2.1 EarLier experimental studies 2.2.2 Recent work on mediating factors 2.3 The role of output in lexical acquisition 2.3.1 Controversial issues 2.3.2 The noticing function of output in lexical acquisition 2.4 Need for further research Part Ⅱ METHODOLOGY Chapter Three Research Design 3.1 Research questions 3.2 Study One 3.2.1 Participants 3.2.2 Instruments 3.2.3 Data collection 3.2.4 Data analysis 3.3 Study Two 3.3.1 Participants 3.3.2 Data collection 3.3.3 Data analysis Part Ⅲ RESULTS AND DISCUSSION Chapter Four Task-Type Effects on the Overall Lexical Acquisition 4.1 Immediate and delayed task-type effects 4.2 The role of L2 Proficiency in task-induced lexical acquisition -. 4.3 Summary Chapter Five Task-Type Effects on the Acquisition of Different Types of Lexical Items in Terms of Salience 5.1 The acquisition of single words 5.1.1 Overall word knowledge gain 5.1.2 Different types of word knowledge gain 5.2 The acquisition of formulaic sequences 5.3 Summary Chapter Six Task-Types Effects on Learner Noticing of Lexical Items across Different Stages of Tasks 6.1 Noticing during the first exposure to input (Stage 1) 6.2 Noticing during the input-related output process ( Stage 2) 6.2.1 Aspects of the noticed lexical problems in Stage 2 6.2.2 Handling of noticed lexical problems in Stage 2 6.3 Noticing during the second exposure to input ( Stage 3) 6.3.1 Amount and type of noticing in Stage 3 6.3.2 Level of noticing in Stage 3 6.3.3 Relationship between LLREs in Stage 2 and Stage 3 6.4 Effects of noticing on lexi~al incorporation 6.4.l Relation of noticing in Stage 2 to noticing in Stage 3 and incorporation 6.4.2 Relation of noticing in Stage 3 to incorporation 6.5 Summary Part Ⅳ CONCLUSION Chapter Seven Findings, Implications and Limitations 7.1 Major findings 7.1.1 Task-type effects on the acquisition of the overall lexical knowledge 7. l. 2 Task-type effects on the acquisition of different types of lexical items 7.1.3 Task-type effects on learners' noticing of lexical items 7.2 Implications 7.2.1 Theoretical implications 7.2.2 Methodological implications 7.2.3 Pedagogical implications 7.3 Limitations and suggestions for future research References Appendices Appendix A Input Passage Appendix B Task Administrator Worksheets Appendix C Vocabulary Pretests Appendix D Vocabulary Posttests Appendix E Wang's Think-Aloud Protocol in Stage 3 Appendix F Questionnaire Results