CHAPTER 1 INTRODUCTION

This book attempts to contribute to second language acquisition by focusing on incidental vocabulary learning and retention through exposure to TED-talks in second language（L2）settings.It also examines the effectiveness of two pedagogical treatments（L2 captions and repeated viewing），and the role of both learner-related factors and item-related factors in L2 incidental vocabulary learning and retention through viewing.This introductory chapter intends to present a whole picture of the study by first providing the reasons that stimulated the researcher to conduct the present study.It then presents the aims of the study.This chapter further proceeds by sharing the research questions and hypotheses of the study.Finally，it outlines the structure of the study.Overall，this chapter intends to provide an overview of the book prior to moving forward to the next chapters.