… In psychological terms, “mood” is a weather report for your personal emotions, a measure of balmy good cheer or dreary storms. But our emotions, naturally, are influenced by the same winds of change that blow on every other person’s. …
The idea of scientifically measuring such moods traces back at least as far as the 1930s, when George Gallup, the man who would one day be described by Time magazine as the “Babe Ruth of the polling profession,” founded the American Institute of Public Opinion and committed himself to collecting accurate data on the whole nation’s sensibilities, unskewed by the ulterior motives of political parties or interest groups. …
In the modern era, you no longer need to ask people how they feel. The collective mood is more pervasive and more obvious than ever. On Twitter and on Facebook, millions of us offer up-to-the-minute updates on our state of mind with essentially no prompting whatsoever. CONT.
Steven Hyden, New York Times Magazine