Correction Appended

WHAT does it take to get Americans riled about invasions of privacy?

Every week seems to bring reports of a new breach of the computer networks that contain our most intimate personal information. Scores of companies -- including Bank of America, MasterCard, ChoicePoint and Marriott International -- have admitted to security lapses that exposed millions of people's financial information to potential abuse by identity thieves. For the most part, however, Americans have reacted with a collective shrug, many privacy experts said.

"They feel they can't do anything about it, anyway," said Lawrence Ponemon, the founder of a privacy consulting company, the Ponemon Institute. "They move on with their lives."

Has something fundamental changed in Americans' attitude toward privacy? Conditioned by the convenience of the Internet and the fear of terrorism, has the public incrementally redefined what belongs exclusively to the individual, and now feels less urgency about privacy?

Mr. Ponemon says this may be the case with young people, who post the most personal information about their lives and loves on blogs that can be read by millions.