The annual survey, part of the Center's Digital Future Project, involved contacts with 2,000 American households. In 2005, the survey found that the amount of time family members spent together averaged about 26 hours a month.
That shared time had dropped precipitously to just under 18 hours per month by 2008, slashing overall time spent together by 30 percent.
Women seem to be bearing the brunt of this Web-linked isolation, with more than 49 percent reporting feeling "sometimes" or "often" ignored by other family members, compared with only about 39 percent of men reporting the same.
Meanwhile, in 2000, 11 percent of people surveyed said younger people (under 18) were spending "too much time" online, vs. 28 percent in 2008.
This trend toward decreased family time dovetails with the emergence and rapid growth of online social communities, the researchers noted.
"Social networks such as Twitter and Facebook exploded in 2007. At that time, more than half of people online said this online community was as important as their offline community," Gilbert said. "Many technology issues are pulling on the family which, in the modern world, has enough pressures."
Where might all this lead?
"Certainly a lack of collective experience and face-to-face time will lead to a breakdown in communication, decreased opportunities to experience the world together, increased alienation of children," Gilbert said. "Family breakdown leads to destructive behavior."
In response, some families are beginning to budget time for Internet use, setting curfews or proclaiming no Internet on weekends.
"There are ways we can put little fences around our involvement with the Internet," Gilbert said. "We need to remember how valuable it is to spend time together and experience the world together. Nothing can substitute for face-to-face time."
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