The internet is full of useful information, time-wasting social networks, and cat videos. Alongside all of that are the ads, many of which look a lot less like ads these days. As ad blockers have become increasingly popular, websites have made the ads more integral to the content. Computer scientist Arvind Narayanan, along with his colleagues from Princeton and Stanford have developed a new proof-of-concept ad blocker that spots ads more like a human. They call it the “Perceptual Ad Blocker.”

It was Facebook’s changes to ads, making them look like other posts, that spurred Narayanan and his team to action. While the ads are now part of the stream to evade ad blockers, Facebook is required to include certain elements for its human users, like privacy controls and text that makes it clear you’re looking at an ad. That’s too subtle for your average ad blocker, which looks at the code in search of ads.

When you look at a webpage, you can probably pick out things that are ads even if they’re styled to look like the rest of the content on the page. You might notice the tiny “sponsored” text some sites use, or the logo of a sponsored link aggregator. For example, many of Facebook’s ads are designed to look and behave just like a regular post from your friends. That makes it difficult, if not impossible, for a traditional ad blocker to spot. Perceptual Ad Blocker looks for the same things you would, and uses them to identify ads.

Perceptual Ad Blocker scans a page, looking for container sizes, specific icon graphics, and text like “sponsored” in order to find the ads on a page. It doesn’t bother looking at HTML tags when looking for ads, because those can be obscured by sites attempting to thwart ad-blocking.

If you want to take Perceptual Ad Blocker for a spin, you can do so with a Chrome extension. However, this is only a proof-of-concept. It’s not really an ad blocker so much as an ad identifier. It simply overlays ads with text that reads “This is an ad.” The team tested Perceptual Ad Blocker on 50 of the top sites known to engage in anti-blocking, and it successfully found the ads on all of them.

Narayanan stops short of calling Perceptual Ad Blocker “undefeatable,” but acknowledges this could be the end of the ad blocker arms race. There are laws that require companies to label ads as such so they do not mislead consumers. An ad blocker that can identify ads like a human would be nearly impossible to circumvent. The code is available for anyone who wants to check it out.

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