Parental control apps — already known to be a less-than-effective way of helping teens navigate the Internet — have now been shown ineffective at keeping kids away from pornography and other explicit content.

The research, conducted by Oxford Internet Institute (OII) at the University of Oxford, found no evidence that Internet filtering tools are successful in monitoring a child’s exposure to sexual content. “Internet filtering tools are expensive to develop and maintain, and can easily ‘underblock’ due to the constant development of new ways of sharing content,” says Victoria Nash, PhD, co-author of the study and deputy director of OII. “Additionally, there are concerns about human rights violations — filtering can lead to ‘overblocking,’ where young people are not able to access legitimate health and relationship information.”

Nash’s team collected data from a large-scale study that included pairs of children and caregivers in Europe, followed by a secondary study that involved teens from the UK. Self reports revealed children had viewed sexual content on the Internet irrespective of filtering controls put in place by parents. In fact, in more than 99.5% of the cases, the likelihood of young participants being exposed to sexual content was affected by factors other than parental control filters.

“We were also interested to find out how many households would need to use filtering technologies in order to stop one adolescent from seeing online pornography,” says co-author Andrew Przybylski, director of research at OII. “The findings from our preliminary study indicated that somewhere between 17 and 77 households would need to use Internet filtering tools in order to prevent a single young person from accessing sexual content. Results from our follow-up study showed no statistically or practically significant protective effects for filtering.”

The research calls for a re-analysis of present parental control filtering, to find methods that actually balance what content is available to kids online.

“We hope this leads to a re-think in effectiveness targets for new technologies, before they are rolled out to the population,” says Nash. “From a policy perspective, we need to focus on evidence-based interventions to protect children. While Internet filtering may seem to be an intuitively good solution, it’s disappointing that the evidence does not back that up.”

Until parental control technology gets more effective, the best way to protect kids online remains building their digital literacy skills, so they can learn to identify and avoid or deal with negative digital content themselves.