Most Americans Are Wary of Being Tracked Online, Study Says BERKELEY, Calif. - As marketers, browser makers and government regulators spar over efforts to let consumers limit custom advertising online, a new study suggests that Americans are largely unaware of what that means and have a strong aversion to being tracked online. The majority of Americans surveyed by researchers at the Berkeley Center for Law and Technology, which is part of the law school at the University of California, Berkeley, do not want information collected at all about which Web sites they visit, according to the study, which is to be released at the Amsterdam Privacy Conference on Monday. Most of them said they did not find online advertisements useful. And nearly 90 percent said they had never heard of a proposal by the Federal Trade Commission, known as a "do not track" mechanism, that would let users opt out of having their personal data collected for the purposes of serving tailored advertisements. The digital advertising industry has resisted efforts to limit behavioral targeting, pointing out that the free content available on the Internet, including social networks, is powered precisely by that kind of advertising. Browser companies have introduced do-not-track icons for their users, and Microsoft has gone farthest by making it the default setting on its latest version of Internet Explorer. There is still no agreement on whether a do-not-track button on Web browsers would send a signal that information about a consumer's browsing history should not be used to tailor advertisements - or should not be collected at all. And it is up to each Web site to honor a consumer's request or ignore it altogether, because no law requires sites" compliance with users" wishes. The Berkeley survey, financed by a grant from Nokia, presented a series of multiple choice questions on the telephone to 1,230 Internet users in the United States. The survey asked respondents: "If a "do not track" option were available to you when browsing the Internet, which of the following things would you most want it to do?" Sixty percent said they prefer regulation to "prevent Web sites from collecting information" about them; 20 percent said such a tool should allow them to block Web sites from serving up ads; and 14 percent said they would like it to "prevent Web sites from tailoring advertisements" based on sites they had visited. The remaining 6 percent said they did not know or declined to answer. One in five told the researchers that they believed advertisers were not allowed to track people when they browsed medical sites. Four in 10 did not know or declined to answer, while a third correctly said that they could be tracked by marketers. The survey also asked how useful consumers found search and banner advertisements. Two-thirds said they found it "never" or "hardly ever" useful, while 30 percent said "often" or "sometimes." Eight-five percent said they "never" or "hardly ever" clicked on an advertisement. Data mining companies have grown increasingly sophisticated at analyzing consumer behavior both online and offline, through bits of computer code online or loyalty cards and nascent mobile payment options at brick-and-mortar stores. Such data is extremely valuable for advertisers, along with digital platforms like Facebook and Google that survive on advertising dollars. The authors of the study argued that the Federal Trade Commission's proposed mechanism was "a modest intervention." An industry-supported group, the Information Technology and Innovation Foundation, wrote a vigorous criticism of do-not-track proposals in a blog post last week, arguing that "nontargeted advertising" generated less revenue and that "less revenue means less free content and services for Internet users."