A team of researchers from Princeton and Stanford Universities has developed an ad blocker that could mean bad news for online publications.

The Perceptual Ad Blocker was created by Grant Storey, Dillon Resiman, Johnathan Mayer and Arvind Narayanan as part of a study where ad blockers are used as a security precaution.

The team says that online advertising and the supporting infrastructure have the potential to introduce security threats to the user. There’s also the matter of publishers who run adverts that aren’t explicitly marked as such.

While having adverts that aren’t marked as such is misleading, it’s also illegal in countries such as the United States.

So what makes Perceptual Ad Blocker different from the many ad blockers out there?

Rather than scanning through a list of keywords that are used by publishers to block adverts, the Princeton-Stanford solution looks at a webpage to identify adverts.

When we say “look” we mean “look” because the ad blocker scans a webpage looking at the various containers scattered throughout it. From those containers it determines which containers might be running adverts.

Once those have been identified the blocker searches for markers such as the text “sponsored”. Given the results of the study, this ad blocker works and very well at that.

Tests on Facebook proved especially successful with 50 ads being correctly identified and blocked from a sample of 50 ads.

Outside of Facebook the blocker only turned up 3 false positives and 4 false negatives where 100 of the Alexa top 500 websites were tested.

The blocker itself is currently available as a Chrome extension that you can use but it doesn’t remove adverts but rather labels them as adverts.

This – the team says – is to avoid any legal or ethical problems that may arise from the use and testing of this ad blocker but it does hope the existence of Perceptual Ad Blocker launches a debate into the ethics of using extensions such as this.

We do urge you to remember that this is just a proof of concept and your experience won’t be the same as with other ad blockers, so use it at your own risk.