How much can your tweets reveal about you? Judging by the last nine hundred and seventy-two words that I used on Twitter, I'm about average when it comes to feeling upbeat and being personable, and I'm less likely than most people to be depressed or angry. That, at least, is the snapshot provided by AnalyzeWords, one of the latest creations from James Pennebaker, a psychologist at the University of Texas who studies how language relates to well-being and personality. One of Pennebaker's most famous projects is a computer program called Linguistic Inquiry and Word Count (L.I.W.C.), which looks at the words we use, and in what frequency and context, and uses this information to gauge our psychological states and various aspects of our personality.