Introduction

The Introduction
No matter what heading you choose for the introductory section of your proposal, it should, in the most general sense, do two things for the reader:

It should provide a "map" of what is ahead
It should make the reader want to find out more about your research.
More specifically the introductory section to a thesis proposal should tell the reader something about the following:
What is the study about?
Why is it important? What is the problem, question, hypothesis, theory to be tested, etc.?
What is some of the most important relevant work done in this area? What further research is needed in this area?
What can be the usefulness of your study?
In terms of sequencing this information, a move from the general to the specific would be appropriate in many cases. The following questions can serve as a guideline:

QUESTION PURPOSE OF INFORMATION
What is the topic? Orientate the reader by giving some general background to the topic
Why is the topic important? Justify your research by explaining to the reader why this is an important area of research What do we know about the topic in Provide the reader with a context for your general?* research by giving a brief summary of past research
What are some gaps or weaknesses in Justify your research by showing gaps, our knowledge about the topic?* weaknesses, etc
What are you going to do about these Give the reader a general statement about the gaps?** purpose of your research

The questions marked * can be developed in more detail in a literature review. The question marked ** can be developed in more detail in a section that states your research questions, aims, objective, hypotheses etc.

Aims And Objectives
Example 1
The purpose of this study is to investigate the relationship between foreign/second language learners' knowledge of vocabulary and their comprehension in reading formal prose such as that exemplified by