Mitt Romney’s mistake in speaking bluntly at a May fundraiser was not only in the words he spoke but also in failing to anticipate the ears they might reach. An audience that looked like an exclusive group of Republican donors this week multiplied — thanks to the pervasiveness of video technology — to the entire world.

Rapidly changing technology is shrinking traditional zones of privacy faster than most people can adjust, and the future looks no easier to navigate. Some technology companies are creating “wearable devices” that put video cameras in eyewear and watches. Others promote “frictionless sharing” of user locations, reading lists and music choices.

Campaigns desperate to prevent embarrassing video and audio snippets already are confiscating smartphones at closed-door events. But they have largely been overmatched, as time and again moments intended to be kept secret have turned up on the Internet.

“There is a total collapse of the notion of private space,” said Republican strategist Steve Schmidt, a top adviser to Sen. John McCain’s presidential campaign in 2008. “Increasingly, politicians who say one thing behind closed doors and another to the public get caught doing it.”

Researchers studying human interactions with computers find that nearly everybody has accidentally conveyed a message intended for a narrow audience to an uncomfortably broad one — sometimes by doing something as simple as hitting “reply all” on a company-wide e-mail.

Such issues are particularly explosive in the political arena. Campaign operatives seek to warn candidates that they are all but public nearly every second of every day. But experts say humans — no matter how smart, polished or famous — need private space and the more relaxed interactions that allows.

“We all think it’s important that we can say things in private that we’d be mortified if they were said in public,” said David Weinberger of Harvard’s Berkman Center for Internet and Society. “The problem is for politicians, it’s very hard to give up on that sort of privacy. It’s essential to us.”

Psychologist Kelly E. Caine of Clemson University calls the problem “misclosure,” a play on the word “disclosure”: The utterance is intended, but the audience it reaches isn’t. Her research suggests that, in the modern technological era, most everyone commits acts of misclosure — even if the consequences are rarely as severe as they are for politicians.

The pitfalls have been borne out repeatedly on the campaign trail despite aggressive efforts to prevent them.

Romney’s apparent dismissiveness toward the nearly half of Americans who don’t pay federal income taxes was reminiscent of President Obama’s disparaging remarks in 2008 — also taped at a private fundraiser — about some voters fearfully clinging to “guns or religion.”

In May, Obama aides placed the phones of 60 wealthy donors into small plastic bags at the New York City townhouse of Blackstone executive Hamilton “Tony” James for Obama’s $35,800-per-person reception.

Such tactics have not always worked. In early June, the president, in Beverly Hills on a fundraising trip, met privately with two dozen young Hollywood stars — including Jessica Alba, Dianna Agron of “Glee” and “Avengers” star Jeremy Renner — when Obama was under attack from Republicans who accused him of being more interested in rubbing elbows with Hollywood’s glitterati than in tackling the unemployment rate. News of the event broke after the stars began posting photos on their Twitter and Instagram accounts.

In late June, the campaign was burned again when Obama’s phone call to top donors from Air Force One was secretly recorded by a participant and leaked to a reporter from the Daily Beast. Although Obama’s comments generally matched what he said in public, the story cast the president as “weary and maybe a tad worried” as he “repeatedly begged” for money.

“It takes nothing to set an iPhone or Android on record and put it in your shirt pocket during an event,” said Andrew Rasiej, the founder of Personal Democracy Media, which examines the nexus between politics and technology.

Romney also has been burned before. In April, reporters who were not allowed into a fundraiser for the GOP candidate in Palm Beach, Fla., overheard him and his wife, Ann, speaking frankly to donors in the back yard of a private residence.

Romney provided policy details that had gone beyond his public statements, including saying he would eliminate the Department of Housing and Urban Development. Ann Romney, who had been engaged in a debate over the role of women in the workplace, was quoted as calling criticism of her as a stay-at-home mom “an early birthday gift,” almost gloating about the dust-up.

Humans evolved as fundamentally social creatures who easily distinguished between public communications — at a village meeting, for example — and private ones between friends and family members. Intimate communication was key to forming and maintaining relationships that were the building blocks of society.

Betrayal of that intimacy, either accidentally or through intentional penetration of private space, is not new. But improving technology has made it easy for unintended audiences to gain access to damaging or embarrassing words and images, as Britain’s royal family have been reminded in recent weeks as compromising pictures of Prince Harry and Princess Kate spread on the Internet.

What’s striking about the political scandals caused by loose words is how often the wounds are self-inflicted.

Then-Sen. George Allen (R-Va.) famously damaged his reelection campaign in 2006 by calling a Democratic campaign activist wielding a video camera “macaca.” Though Allen knew the camera was rolling, he was taken off guard by the furious reaction after the clip reached a broader audience, many of whom concluded that “macaca” was a slur aimed at the activist, who was Indian American.

Author Katherine Losse, who recounted her experiences as an insider at Facebook in “The Boy Kings,” said the future of private conversation may depend on each member of discussions agreeing to keep confidence with each other. Public figures, meanwhile, must be perpetually on guard.

“Maybe one of the reasons these things keep happening is people can’t do it,” Losse said. “It’s like our brains can’t conceive of a day in which all things are broadcast.”