WASHINGTON — A flood of highly graphic Internet pornography — much of it illegally targeting children — will keep eroding "an already vulnerable culture of marriage" unless social norms change drastically, a Brigham Young University researcher and family therapist said here Tuesday.

Jill C. Manning was in the nation's capital to muster support for more research and spent the day sharing her findings with congressional aides in the absence of senators and representatives, most of whom spend the August recess of Congress in their home districts.

"While much remains unknown about the impact of Internet pornography on marriages and families, the available social science data reveal many negative trends and provides a foundation from which social policy and research agendas may be explored," she said. "As the first Internet generations reach adulthood, it is anticipated that the full magnitude of online pornography's effects will become more evident and alter the pornography debate accordingly."

With access now literally at the fingertips via the Internet, virtual hard-core images have never been easier to get or hide from other family members, she said, noting that the unprecedented growth of sex-oriented online businesses will continue unabated without more education, revised parenting approaches, more law enforcement attention and altering the Internet itself.

Manning, who has reviewed myriad studies of pornography's influence on marriage, family and children, concludes that Internet-distributed pornography is more devastating than its print and video predecessors. Lawyers in one recent nonscientific study reported that an obsessive interest in Internet porn was a factor in more than half of the divorce cases they were handling.

Most who seek help to break a porn addiction are white, married men in their 30s who were exposed to it via the Internet, Manning said. Particularly worrisome, she said, is that children, some as young as 2, are being exposed to graphic images they aren't mature enough to handle.

With few exceptions, the pornography industry "gives only lip service" to keeping minors out of adult sites, she said, noting that many specifically target children.

Marriage becomes the "logical point of impact," she said, adding that her research shows that between 20 percent and 33 percent of the 172 million Internet users in the United States go online with a sexual purpose. Most are married men, but women make up 30 percent of the Internet porn market, she said.

Manning was careful to say that more research needs to be done into the effects of pornography on social relationships, and that cause-and-effect correlations often don't meet scientific review standards. However, she added, ongoing studies are finding a reappearing scientific link — people who have just viewed pornographic images and people who have just been given a powerful narcotic have similar brain chemistry profiles.