A faltering economy explains much of the job shortage in America, but advancing technology has sharply magnified the effect, more so than is generally understood, according to two researchers at the Massachusetts Institute of Technology.

The automation of more and more work once done by humans is the central theme of “Race Against the Machine,” an e-book to be published on Monday.

“Many workers, in short, are losing the race against the machine,” the authors write.

Erik Brynjolfsson, an economist and director of the M.I.T. Center for Digital Business, and Andrew P. McAfee, associate director and principal research scientist at the center, are two of the nation’s leading experts on technology and productivity. The tone of alarm in their book is a departure for the pair, whose previous research has focused mainly on the benefits of advancing technology.

Indeed, they were originally going to write a book titled, “The Digital Frontier,” about the “cornucopia of innovation that is going on,” Mr. McAfee said. Yet as the employment picture failed to brighten in the last two years, the two changed course to examine technology’s role in the jobless recovery.