And so device makers in a post-iPhone world are focused on fingertips, with touch at the core of the newest wave of computer design, known as natural user interface. Unlike past interfaces centered on the keyboard and mouse, natural user interface uses ingrained human movements that do not have to be learned.
“It’s part of the general trajectory we’re on in the computing industry — this whole notion of making computers more open to natural human gestures and intentions,” said Eric Horvitz, distinguished scientist at Microsoft Research.
The latest is a new line of Sony e-readers that the company will introduce Wednesday. For the first time, all have touch screens; Sony decided on the technology after watching person after person in focus groups automatically swipe the screen of its older, nontouch e-readers.
Research In Motion now makes touch-screen BlackBerrys, Amazon.com is expected to make a Kindle with a nonglare touch screen, and Garmin has introduced touch-screen GPS devices for biking, hiking and driving. New Canon and Panasonic digital cameras have touch screens and Diebold, which makes A.T.M.’s, says that more than half the machines that banks order today have touch screens.
Brides-to-be can scroll through bridesmaid dresses on a Hewlett-Packard touch-screen computer at Priscilla of Boston bridal boutiques, and a liquor store in Houston uses the H.P. screen as a virtual bartender, giving customers instructions for mixing drinks. The screens also show up on exercise machines, in hospitals, at airport check-in terminals and on Virgin America airplanes.
“Everyone who touches or takes a reader in their hand, they touch the screen,” said Steve Haber, president of Sony’s digital reading division. “It’s what we do.”
Some people even try to use touch screens when their devices have none.
“I had to use my sister’s BlackBerry to make a call, and I just kept swiping and touching,” said Susannah Wijsen, 40, who works in advertising in San Francisco and had grown used to tapping out phone numbers on her iPhone screen. “It didn’t even occur to me to use the keyboard.”
Though scientists have been working on natural user interface, Apple made touching, swiping and flicking at screens mainstream, said Harsha Prahlad, a research engineer who works with robots and sensors at SRI International, the research institute. “All of the technologies existed, but by bringing it together in a seamless fashion, the iPhone had a lot to do with it,” he said.
Virginia Campbell, 99, learned to type on a typewriter and had never used an A.T.M. or other touch screen. But when her children gave her an iPad two days after it came out, she found touching the screen to be instinctual.
“It was no problem,” said Ms. Campbell, who lives in Lake Oswego, Ore., and uses her iPad daily to write limericks and reread classic novels. “It was a light tap and I have had no trouble at all.”
Shumin Zhai, a research scientist who studies human-computer interaction at the I.B.M. Almaden Research Center in San Jose, Calif., noticed the phenomenon among participants in a study he performed.
“People inevitably point at the screen, thinking something would happen — it’s such a natural behavior,” he said. “My own 2-year-old daughter amazingly could use the iPad and somehow it was intuitive.”
For readers used to turning paper pages, e-books invite touch perhaps more than anything else. Many a Kindle screen has been sullied by errant fingers before their frustrated owners realized that readers turn the pages of an e-book using buttons on the side of the device.
Amazon bought a touch-screen start-up, Touchco, but the current touch-screen technology added too much glare, Jeffrey P. Bezos, Amazon’s chief executive, said in an interview when Amazon introduced the newest Kindle. “It has to be done in a different way,” he said. “It can’t be a me-too touch screen.”
Two of Sony’s previous readers, the Touch and Daily Editions, had touch screens, but they produced a glare and required a hard, forceful touch. In the new versions, Sony removed the top layer of glass from the screen to reduce the glare and effort.
Sony’s new e-readers, ranging from $179 to $299, are not the cheapest out there, but Mr. Haber said people were willing to pay for the features they wanted and touch was at the top of the list. He noted that when Sony’s last line of e-readers was introduced, many people paid $100 more for the touch-screen version.
The next generation of screens might not even need a touch. Instead, they will understand the gestures of people standing in front of them and pick up on eye movement and speech.
“The future’s going to be in fusing together several different natural human behaviors — how people point, gesture and coordinate with each other,” Mr. Horvitz of Microsoft said. “Touch is a beautiful tip of the iceberg for talking about where things are really headed.”