“We are exposing our brains to an environment and asking them to do things we weren’t necessarily evolved to do,” he said. “We know already there are consequences.”

Mr. Campbell, 43, came of age with the personal computer, and he is a heavier user of technology than most. But researchers say the habits and struggles of Mr. Campbell and his family typify what many experience — and what many more will, if trends continue.

For him, the tensions feel increasingly acute, and the effects harder to shake.

The Campbells recently moved to California from Oklahoma to start a software venture. Mr. Campbell’s life revolves around computers. (View a slide show on how the Campbells interact with technology.)

He goes to sleep with a laptop or iPhone on his chest, and when he wakes, he goes online. He and Mrs. Campbell, 39, head to the tidy kitchen in their four-bedroom hillside rental in Orinda, an affluent suburb of San Francisco, where she makes breakfast and watches a TV news feed in the corner of the computer screen while he uses the rest of the monitor to check his e-mail.

Major spats have arisen because Mr. Campbell escapes into video games during tough emotional stretches. On family vacations, he has trouble putting down his devices. When he rides the subway to San Francisco, he knows he will be offline 221 seconds as the train goes through a tunnel.

Their 16-year-old son, Connor, tall and polite like his father, recently received his first C’s, which his family blames on distraction from his gadgets. Their 8-year-old daughter, Lily, like her mother, playfully tells her father that he favors technology over family.

“I would love for him to totally unplug, to be totally engaged,” says Mrs. Campbell, who adds that he becomes “crotchety until he gets his fix.” But she would not try to force a change.