Take time to think about what you would like to know and how you could best come to that knowledge. If you are a graduate student writing a thesis, you will not receive a topic assignment from a professor; you must make that assignment to yourself.
Select one of the patterns as the next smaller increment you will search.
Using either process, you might decide to narrow the nonverbal topic to eye contact.
Discuss the assignment with class members and with the professor. If you have been assigned to critique, you will want to select a topic you find intriguing so your critique will engage the reader.
If the assignment is made orally in class, take notes. If you are intending to review--such as review literature for a specific area--you will need to identify some areas of interest and go on an expedition to the library to discover which of those areas provides you with available material to review.
To accomplish that goal, you must select a narrow topic rather than a broad and sweeping one.
That narrow topic becomes the starting point for your paper, so select a topic that interests you in some important way.
If you looked for articles about nonverbal communication in academic journals, you would learn that your search generated hundreds of articles. Once you discover this problem, narrow your topic by increments.
You can decide the increments for yourself or you can use the articles you generated to help you.
You may feel as though you are leaving out something important if you narrow your topic to such a small slice of the information. Part of the challenge of reading, writing, and conducting research is learning to limit your topic so you can thoroughly and exhaustively examine it.
Your goal is to examine this topic in minute detail.