“People wait for all sorts of things every day, sometimes more happily than others,” wrote the interface designer Bob Stahl in a 1986 article for Computerworld. “The problem is how the user feels about waiting.” At the time, machines were often slow and unreliable, and users didn’t always know when their programs crashed. A “progress bar” might mitigate frustration, Stahl suggested, by signaling that bits were flipping with a purpose somewhere deep inside the C.P.U.

The push to make computers more user-friendly gained momentum in the early 1980s. At a 1985 conference on the nascent field of computer-human interactions, a graduate student named Brad A. Myers presented a paper on the importance of what he called “percent-done progress indicators.” “I had the sense that they were useful and important, and not used as much as they should have been,” Myers says today. (He’s now on the faculty at Carnegie Mellon University.) He told his colleagues that progress bars made computer users less anxious and more efficient, and could even help them to “relax effectively” at work.

To prove his point, Myers asked 48 fellow students to run searches on a computer database, with and without a progress bar for guidance. (He used a capsule that filled from left to right — like a giant thermometer from a charity drive, tipped on its side.) Then he had them rate their experience. Eighty-six percent said they liked the bars. “People didn’t mind so much if it was inaccurate,” Myers says. “They still preferred the progress bar to not having anything at all.”