NEW YORK — Americans say they don't like to give out personal information on the Internet. But, according to a new survey, they often do — inadvertently or not.
A survey by the Pew Internet and American Life Project found that an overwhelming majority of Web surfers worry about strangers getting personal data about them, but few take basic precautions.
In fact, a majority of Internet users are willing to give Web sites the same information they claim they want to keep private, the study released Sunday said.
Much of the worry stems from a fear of the unknown, rather than a sweeping mistrust of Internet businesses, said Lee Rainie, the Pew project's director. The study found new users more concerned about privacy than online veterans.
"It's a new technology," he said. Newcomers "are just a little bit more leery than veterans are."
Many Web sites create user profiles containing such data as e-mail addresses, favorite books or clothing sizes. Some sites also track users' surfing habits, often without their knowledge, to better target ads and products.
Internet companies argue that such tracking is often performed anonymously and helps them customize sites and content to match users' interest.
But only 27 percent of Internet users accept the industry's claim that tracking is helpful. Fifty-four percent consider it harmful, and 11 percent believe it both helps and hurts.
The random telephone survey of 2,117 adult Americans, including 1,017 Internet users, was taken May 19 to June 21. The margin of error was plus or minus 3 percentage points for the questions asked only of Internet users.
According to the survey, 86 percent of online users are "very concerned" or "somewhat concerned" about others getting their personal information.
Sixty-two percent of users with less than six months of experience are "very concerned," compared with half the users online for three or more years.
But only 10 percent of all users set their Web browsers to reject cookies, the basic tools that sites use to track surfing habits. Fifty-six percent do not even know what cookies are. Only 5 percent use special software designed to permit anonymous surfing.
And 54 percent of users have chosen to give personal information such as a name or e-mail address, with another 10 percent willing to do so. That's nearly two-thirds of Internet users agreeable to giving up their privacy.
Does this mean fears of privacy breaches are overstated?
Jason Catlett, a privacy advocate familiar with the study, compared the privacy concerns to attitudes toward crime.
"People say they want to be secure, but they still go out late at night in the entertainment areas of cities," Catlett said. "Does this mean we should send the police force home at 5? I don't think so."
He agreed with the 86 percent of Internet users who believe sites should ask permission before collecting personal information.
Such an "opt in" requirement lets users set the terms for when they give personal information. But sites now generally assume such consent unless users specifically "opt out" of such surveillance.