Apparently the need to post one's current status is a clear sign that one is too self-involved. And possibly that you've got too much time on your hands and need to get out more. According to the article:
Hundreds of students participated in the reattach, published in the journal Computers in Human Behaviour. It found that those who were vain tended to tweet more, but those who were middle-aged and fond of themselves preferred Facebook.
The researcher (I can't remember his name and it's not in the photograph I took of the article !) found that: "Facebook acted as a mirror to the user's perceived image."
So there you have it. If you constantly need the affirmation that others are reading your posts, or you are just too self-involved, then monitor your Facebook usage. It could be telling the world more about yourself than you thought it was.