Yesterday Facebook rolled out a new ad system where people's updates get converted into "sponsored story" ads fed to their friends. But this is hardly the first time advertisers have tried to feed us ads stealth-style.

What happens when advertisers try to control your mindS

Let's get subliminal

Before we tackle this latest Facebook social media apocalypse, let's consider the history of stealthy high-tech advertising. In the 1950s, ad agencies started reading Freud and tried to create ads that appealed to our subconscious minds. Vance Packard's great book The Hidden Persuaders details the secret history of psy-ops advertising during that time. It's this era that gave us the famous "sex spelled out in ice cubes" gin ad, as well as commercials that supposedly flashed words at you so quickly that they'd zoom right into your unconscious mind.

Subliminal advertising never really caught on, though it became a touchstone in popular culture and conspiracy theories. There was little scientific proof that subliminal messages actually could control people's behavior, but nevertheless subliminal messages in ads were outlawed in the United States and a few other countries during the 1970s.

Skip ahead a few decades, and stealthy advertising mind control techniques hadn't progressed much beyond "write a catchy jingle that becomes an ear worm."

The Gmail problem

And then came the Web, with its promise of contextual advertising. Google's AdSense was greeted with some enthusiasm - after all, who doesn't want ads that are relevant? But then Google turned its algorithms on Gmail, creating ads whose relevance was based on the mail you were reading. This led to awful bloopers like people reading about the death of a loved one getting funeral home ads. And created a huge outcry among privacy advocates and Adbusters types who thought there was just something generally creepy about Google's algorithms riffling through everybody's private mail to deliver "relevant" ads.

Things got even weirder after that, as if Gmail unleashed every advertiser's bottled-up urge to control people's minds in the most high-tech, bizarre ways possible.

Getting sneaky and going viral

Probably the strangest of these was the "directional audio billboard," which used a technique for shooting sound over long distances directly into somebody's ear. So you'd walk past a billboard, and then when you got several feet away, you'd suddenly hear a voice in your ear telling you about the product. The technique was used in New York a few years ago to advertise a show called Paranormal State.

Other ads relied on stealth marketing: They masqueraded as internet memes. Media critic Douglas Rushkoff popularized the term "viral" to explain this kind of advertising in the 1990s, and it continues on today even stronger than before. Every movie that has an alternate reality game (ARG) or viral video campaign associated with it is part of this trend. In some ways, the viral campaign is similar to the old subliminal campaigns of the mid-20th century - they're intended to influence you by wrapping the advertiser's message in something that worms its way into your subconscious.

Viral ads, like this Levis ad below, show you something that's supposed to look like it's just a fun video created by regular people - but as you watch, your subconscious mind may register that they're always jumping into Levis jeans. Note that there's no direct advertisement, nor any reference to Levis other than the jeans themselves.

We don't need to control your mind to control you

In a way, the new Facebook "sponsored story" ads are aimed at turning your Facebook updates into viral advertisements against your will. We asked viral media expert Douglas Rushkoff what he thought of the new Facebook model, and he told us by e-mail:

The thing that's spooky here is not just that advertisers can get leverage by using the comments of "real people." It's that our behavior as consumers is itself being retrained. We are to feel like we are living in the ads. Whether or not any of our comments is actually chosen, it could be. It's like a panopticon, where the surveillance is all that is required to change our behavior. Those of us who remain on Facebook are now ever closer to identifying completely as consumers, trying to please the corporations.

The truly scary part is that you can't opt out of Facebook's sponsored story model. So you're about to start advertising products to your friends, whether you like it or not.

So Facebook has sidestepped the problem of how to control your mind and get you to buy things or recommend them to your friends. They don't need to control your brain to get you to advertise for them. They just need to know who your friends are, and what you're saying to them. Their ad placement algorithm does the rest.