The findings, released Sunday at the annual meeting of the American Psychological Association, appear likely to bolster the expanding acceptance of compulsive Internet use as a real psychological disorder.
"Marriages are being disrupted, kids are getting into trouble, people are committing illegal acts, people are spending too much money. As someone who treats patients, I see it," said David Greenfield, a therapist and researcher who conducted the study.
Alcohol and drug addictions have wrecked families for generations, reports CBS News Correspondent Lou Miliano, but John's dad is neither hooked on alcohol nor drugs, yet the problems are similar. John blames the Internet.
"My father comes home from work and goes downstairs, and talks on that all night until he goes to bed," complained the Boston-area youngster. "In fact, my parents are getting a divorce over it."
Kimberly Young, a pioneer in the new field of research, said the study is so broad that it "adds a layer of legitimacy to the concern that Internet addiction is real."
However, the 6 percent figure is lower that some earlier estimates of 10 percent or more that stemmed largely from research on college students.
Greenfield, a psychologist in West Hartford, Conn., carried out the study jointly with ABC News. He collected 17,251 responses to an Internet use questionnaire distributed and returned through the Internet.
He adapted his questions from a widely used set of criteria for gambling addiction. For example, the questionnaires asked if participants had used the Internet to escape from their problems, tried unsuccessfully to cut back, or found themselves preoccupied with the Internet when they were no longer at the computer.
If participants answered "yes" to at least five of 10 such criteria, they were viewed as addicted, just as in gambling. A total of 990 participants, or 5.7 percent, answered "yes" to five or more questions. With an estimated 200 million Internet users worldwide, that would mean that 11.4 million are addicts.
The question about using the Internet as an escape yielded more "yes" answers than any other: 30 percent.
Greenfield's analysis of the data suggests that Internet users' feelings of intimacy, timelessness and lack of inhibition all contribute to the addictive force of the Internet.
"There's a power here that's different than anything we've dealt with before," said Greenfield.
Researchers did caution that, while one of the best estimates yet, the 6 percent figure is based on a group of people who use only one Web site, however broadly aimed.
Greenfield, though, argued that his estimate is conservative. He added that, just as a drug is most addictive when absorbed diectly into the bloodstream, the Internet's potential for abuse will grow with modem speeds and ease of access.
Researchers said Internet addiction will ultimately be broken down into several categories, perhaps revolving around sex and relations, consumerism, gambling, stock trading, and obsessive Internet surfing for its own sake.
Therapists at the psychology meeting said they have successfully treated some Internet addicts, often with a mix of talking sessions and programs aimed more narrowly at reducing a sharply defined set of behaviors.