本书是作者在新西兰奥克兰理工大学文学院完成的英语应用语言学博士学位论文。本书的主要研究内容是：对英语作为第二外语教学课堂中的师生之间和学生之间在自由交际活动过程中出现的偶发性聚焦形式进行了对比性的研究，从聚焦形式、反馈形式、语法项目和即时理解四个方面进行了详细对比和分析。
　　本书可以为从事第二语言习得领域研究的学生和教师、科研工作者、从事英语教学的教师和科研工作者，从理论和教学实践的角度提供该领域一些新的发现，并对今后该领域的研究提供了研究方向。

CHAPTER 1 INTRODUCTION
1.1 Overview
1.2 Background
1.3 Research questions
1.4 Thesis outline
CHAPTER 2 THE COGNITIVE APPROACH TO SECOND LANGUAGE ACQUISITION
2.1 Introduction
2.2 Input
　　2.2.1 Positive evidence
　　2.2.2 Negative evidence
　2.3 Apperceived input (noticed-input)
2.4 Comperhended input
2.5 Intake
　　2.5.1 Attention
　　2.5.2 Linguistic knowledge
2.6 Integration
2.7 Output
2.8 The relationship between cognitive processes and focus on form
2.9 Summary
CHAPTER 3 THE INTERACTIONIST APPROACH TO SECOND LANGUAGE ACQUISITION
3.1 Introduction
3.2 The interaction hypothesis
3.3 Negotiation in SLA
　　3.3.1 Contribution of negotiation to comprehensible input
　　3.3.2 Contribution of negotiation to modified output
　　3.3.3 Contribution of negotiation to awareness of linguistic features
3.4 The relationship between the interactionist approach and focus on form
3.5 Summary
CHAPTER 4 FOCUS ON FORM
4.1 Introduction
4.2 Focus on form
　　4.2.1 Planned focus on form and incidental focus on form
　　4.2.2 Reactive versus preemptive focus on form
4.3 General characteristics of focus on form episodes
　　4.3.1 Approach
　　4.3.2 Instigator
　　4.3.3 Linguistic focus
　　4.3.4 timing
　　4.3.5 Source
4.4 Categories in Reactive FFEs
　　4.4.1 Trigger
　　4.4.2 Response
　　4.4.3 Uptake
4.5 Categories in Student-initiated FFEs
4.6 Categories in Teacher-initiated FFEs
4.7 The framework of identifying FFEs for the present study
4.8 Summary
CHAPTER 5 RESEARCH CARIABLES IN THE STUDY
CHAPTER 6 METHODLLOGY
CHAPTER 7 RESULTS
CHAPTER 8 DISCUSSION
CHAPTER 9 CONCLUSION