Filtering Filth

Web filters: Which ones work?

Artificial intelligence expert Keith Devlin wrote that a computer will never be able to tell the difference between “time flies like an arrow” and “fruit flies like honey.” Add to this mix “she unzipped their flies like there was no tomorrow,” and you get some idea of the challenge faced by software manufacturers hawking filters to protect children from the nastiness on the Web. The filters are supposed to block access to sites parents wouldn’t want their children to see.

The Web community has insisted that government regulation of pornographic Web content–as in last year’s Communications Decency Act–is unnecessary because software filters can do the job. Now that the Supreme Court has ruled the CDA unconstitutional, that bluff has been called. Do filters work? And which ones work best?

In essence, all filter programs work like search engines in reverse, keeping out anything with certain words or combinations of letters. The Sussex County Fair Web page has been blocked by filters because it contains the three letters s-e-x. The breast-cancer survivors group found its discussion blocked by America Online (which quickly apologized). Even the Web page for Microsoft’s Encarta encyclopedia has been blocked, presumably because somewhere there was a mention of s-e-x or even b-r-e-a-s-t-s.

Software companies have two different approaches to marketing the filter programs. One evokes law enforcement. This category includes SurfWatch as well as Cyber Patrol (motto: “To Surf and Protect”), which operates from a screen that looks like the command center of Rescue 911. Other filters evoke Mary Poppins, with names like CYBERsitter and Net Nanny. Despite its cozy name, CYBERsitter is in one way the strictest of the programs: It’s a tattletale. The software keeps a log of the sites the child has attempted to access, “including attempts to access blocked material.” Net Nanny’s more liberal approach is indicated by its two-pronged motto: “The Best Way To Protect Your Children And Free Speech On The Net.” It provides parents with a suggested list of sites to exclude, but nothing is excluded without being specifically designated by the parents. As a spokesperson told me in an e-mail, “We do not automatically block, as that would be infringing on your rights.” Think Mary Poppins in a Lilith Fair T-shirt.

A ll the filters are designed to block sites with explicitly sexual text or pictures, and most also screen out sites dealing with drugs, alcohol, hate speech, and gambling. Filters fail in two ways: over-inclusiveness–blocking sites that shouldn’t be blocked–and under-inclusiveness–letting bad stuff through. All the filter products claim to have sophisticated algorithms to avoid these pitfalls. The challenge is in applying a formulaic approach to a heavily context-sensitive sorting problem. Cyber Patrol says that it excludes sites that advocate drug use or bigotry, but that it does not exclude “opinion or educational material, such as the historical use of marijuana or the circumstances surrounding 1940’s anti-Semitic Germany.” As Devlin’s example shows, this is easier in theory than in practice. CYBERsitter, which touts its sophisticated content-based filters, blocks all sites with the word “anarchy.”

But over-inclusiveness is less troubling to parents than under-inclusiveness. In testing each of the filters I was able to pull up X-rated material without much effort. Filters may prevent access to certain sites, but blocked sites can show up when kids use search engines, and there is nothing to prevent kids from reading the raunchy descriptions of the sites or writing down the Web addresses and going off to a friend’s house–or to the local public library, which, in keeping with cherished anti-censorship policies, probably doesn’t use filter software.

Filters can protect kids from accidentally (or intentionally) visiting a Web site that includes material deemed inappropriate by their parents, but they are limited to what we might term the “pull” side. The bigger problem is on the “push” side, and there the filters are helpless. One of the boys in my Cub Scout troop received, via AOL e-mail, a photograph of two men having sex. It was sent as a joke by an older boy he knew. My son, then 11, participated in a sports discussion group on Prodigy. The group was exceptionally kind and protective, except for one participant, who was cut off by the discussion leader for general obnoxiousness. He retaliated by using a free AOL account to send 5,000 copies of an obscene e-mail to everyone who had ever participated in the Prodigy discussion, including my son.

Coming soon are filters based on criteria developed by particular groups. Parents will be able to select from filters endorsed by anyone from the Christian Coalition to the National Education Association. Ultimately, the W3C plan, developed by the international World Wide Web Consortium, will provide standard ratings, to be assigned to each page by its developer. Parents will be able to set their browsers to deny access to pages without ratings. And so they can breathe easier, knowing that their children will only be able to see pages certified as suitable by their own operators.

Meanwhile, you can download trial versions of filter software to find the one you like best. That decision will be based more on your technical facility than on your notions of what material you want your kids to see, because the programs vary much more in their dependence on parental tweaking than on their approaches to excluding material. Parents who are less adept than their kids at using the Internet will probably prefer CYBERsitter. It errs on the side of exclusion, and was especially thorough at preventing even the results of Web searches that included inappropriate URLs. Parents who are willing to devote the time to setting their own parameters will be better off with Cyber Patrol. It allows separate settings for separate users, important for families with older children or children of different ages. It also makes it possible for parents to block outgoing information, to prevent kids from revealing their last names, phone numbers, addresses, and passwords in an online chat. Ultimately, though, even the best filters are a limited and temporary solution. None are as effective as good communication and (maybe even more important) keeping the family computer in a central location so that all surfing is done within earshot.

But filters aren’t just for concerned parents. The cover story in the last issue of the business magazine Across the Board identifies nonbusiness-related use of the Web as a serious problem at the office. Among the most frequent visitors to Penthouse magazine’s Web site are employees at AT&T, Hewlett-Packard Co., IBM, and NASA. One statistic floating around is that workers spend about 90 minutes a day on nonwork-related computer games and Web surfing, with an estimated productivity cost of $50 billion. And, as SurfWatch’s promotional literature is happy to point out, filters can help protect management from liability for permitting sexually explicit material in the workplace. The real market for filters isn’t Mom and Dad–it’s Dilbert’s boss.