“It’s not the technology. It’s user acceptance that’s holding us up right now,” Professor Miller said.

This is not to say experts and consumers don’t see potential benefits.

Scott Fischer, 55, the chief executive of a privately held recruiting firm in Chicago, foresees a variety of situations in which autonomous vehicles would be a major advantage. “I’m not skeptical at all,” Mr. Fischer said.

Mr. Fischer, who took part in a study of older drivers conducted by the Massachusetts Institute of Technology’s AgeLab and the Hartford Center for Mature Market Excellence, part of the insurance company The Hartford, said autonomous cars could give him more peace of mind about his two daughters, who are in their 20s and have limited driving experience. “They don’t drive as much they take Uber,” he said, “so I see the safety aspects.”

For his father, who is in his early 80s and facing driving challenges because of vision issues, an autonomous vehicle would be a way to get around on his own, Mr. Fischer said. And for his own part, Mr. Fischer would let the car take over when he was tired on a long drive or needed to read email.

“But I want to see proof of concept that the technology actually works,” he added.

Joseph Coughlin, director of the M.I.T. AgeLab, said that for the study’s participants, who ranged in age from 50 to 69, there was no reflexive aversion to technology-assisted driving. “If they see it as useful or enhancing safety,” he said, “they’re willing to pay for it.”