Here’s a depressing thought: America’s productivity is rising on the backs of scared office workers. That’s essentially the explanation offered by Michael Feroli, chief U.S. economist at JPMorgan (JPM), for the 1.6 percent second-quarter gain reported Aug. 8 by the Labor Department. The productivity number is calculated by dividing output by hours worked. If the denominator isn’t rising to fully reflect those fear-induced work hours, voila — productivity rises. “Workers are still scared, and so probably could be induced to work harder or longer than usual out of fear of losing their jobs,” Feroli says.