Last spring, however, Gloria Mark at UC Irvine and collaborating U.S. Army scientists produced another intriguing study involving e-mail.

FORBES: Are Smartphones Making Us Dumber?

In one seminal study in 2005, the University of California at Irvine informatics professor Gloria Mark found that information workers on average switch tasks every three minutes.

FORBES: Are Smartphones Making Us Dumber?

The Journal talked to Gloria Mark, a professor at the University of California, Irvine, who says it can take 23 minutes for a worker to get back to the task at hand after a distraction.

FORBES: How To Overcome Workplace Distraction