(Reuters Health) – Parents often rely on filtering software to block children’s online contact with bullies, predators, pornography and other inappropriate material, but a new study casts doubt on the effectiveness of these tools.

Researchers conducted 1,030 in-home interviews with 515 British parents and their adolescent children. Overall, children with filtering software on their home computers were less likely to report negative online experiences, the analysis found.

They report in the Journal of Pediatrics March 14 that 17 percent of youngsters with filters and 22 percent of those without reported negative online experiences.

“Internet filtering, on its own, does not appear effective for shielding adolescents from things that they find aversive online,” lead author Andrew Przybylski said in an email. A psychologist, Przybylski is a senior research fellow at the Oxford Internet Institute at the University of Oxford in England.

“Parents may feel reassured in knowing they have internet filters in their home, but our results suggest that such filters do not safeguard against young people seeing things that may frighten or upset them,” he said.

“As young people grow into adults, there has to be a degree of risk tolerance as they build their own resilience. Keeping open lines of communication is key,” he said.

Michele Ybarra, president and research director for the Center for Innovative Public Health Research in San Clemente, California, said the study underscores the need for parents to discuss their concerns about the web with their children.

“Network-level filtering doesn’t necessarily keep our children safe from unwanted exposures online,” Ybarra, who was not involved in the study, said in a phone interview.

“It’s really important to talk to your kids about how to keep their information safe online,” she said. “If you would prefer your child not look at pornography, talk to them about what that means to you.”

From , the researchers interviewed randomly selected parents and roughly an equal number of boys and girls ages 12 to 15 in households across the UK.

On top of their price tags, filters also carry other costs, the authors write

Nearly one in six youths reported having at least one negative experience online in the past year, and 8 percent reported being contacted by a stranger seeking to befriend them.

Schools and libraries have long used software filters to shield adolescents from potentially troublesome online interactions, the authors write. Major British service providers now filter new household connections by default, presuming that the filters safeguard children.

But the difference was so small that researchers dismissed it as random

The researchers were surprised to find what they described as “equivocal to strong evidence” that filters failed to reduce adolescents’ risk of aversive online experiences. Moreover, they expressed concern that filtering technology provides false assurance to parents and other caregivers.

“It is thus hard to visita el sitio web justify the assumption that the benefits of household-level Internet filtering outweigh (the) costs,” they write.

“Not all exposure to sexual material is bad, particularly for LGBTs (lesbian, gay, bisexual and transgender) who are lacking education in the schools,” Ybarra said.

“It is possible to have a healthy positive online experience, and we as adults can help adolescents experience it as such,” she said.

“Students must develop skills to evaluate information from all types of sources in multiple formats, including the Internet,” it says. “Relying solely on filters does not teach young citizens how to be savvy searchers or how to evaluate the accuracy of information.”

The authors cite the ubiquitousness of internet access outside the home, including on mobile phones, as well as adolescents’ possible resistance to admitting negative online experiences as limitations of their study.

Moreover, nearly a quarter of the parents who participated in the study were unaware of whether their internet connections were filtered.