A quick experiment. Before proceeding to the next paragraph, let your mind wander wherever it wants to go. Close your eyes for a few seconds, starting ... now.

And now, welcome back for the hypothesis of our experiment: Wherever your mind went — the South Seas, your job, your lunch, your unpaid bills — that daydreaming is not likely to make you as happy as focusing intensely on the rest of this column will.

I’m not sure I believe this prediction, but I can assure you it is based on an enormous amount of daydreaming cataloged in the current issue of Science. Using an iPhone app called trackyourhappiness, psychologists at Harvard contacted people around the world at random intervals to ask how they were feeling, what they were doing and what they were thinking.

The least surprising finding, based on a quarter-million responses from more than 2,200 people, was that the happiest people in the world were the ones in the midst of enjoying sex. Or at least they were enjoying it until the iPhone interrupted.