Tired of seeing recommendations on the web for toys when you don’t have kids, or for couples’ getaways if you’ve just gone through a break-up? For years, we’ve been hearing about targeted advertising: companies trying to home in on the right demographics by advertising in places that are more likely to reach them (beer commercials during sports games, kitchen appliance ads after cooking shows—you get it).

In recent years, companies have taken these targeted campaigns a step further by analyzing users’ search histories and emails for information on the kinds of ads that are likely to suit them. A pair of shoes you mentioned in an email to a friend, for example, might well pop up in an ad on your next Google search.

But increasingly more firms are venturing into a new, uncharted field of marketing that seems plucked right from the outlandish minds of Hollywood screenwriters: mood advertising. Or, as it is known in the industry, “affective computing.” More than a hundred patents have already been filed in the United States for these emotion-sensing technologies of the future.

These include everything from ATMs that can read facial expressions to tell if you’re in the mood to see an advertisement when you take out cash, to products geared to change their price levels depending on your personal reaction to them. Already, some music streaming outlets can detect what kind of mood you’re in based on your search history, for example, and then serve you up a playlist catered to your emotional state. It’s only a matter of time before these companies will no longer track what you type into your search engine, but track—and even predict—how you feel instead. Welcome to the strange world of tomorrow: By using sophisticated sensors and face-reading machines, companies may even know your mood before you do.

This kind of tracking of human behavior has not gone without its fair share of backlash. In 2013, Massachusetts Rep. Mike Capuano drafted the We Are Watching You Act in Congress, stating that companies should be compelled to alert consumers when sensors are being turned on to track their behavior, and allow consumers to opt out of this emotion-sensing technology. “The most difficult part is getting people to realize that this is real,” Capuano said. “People were saying, ‘Come on. What are you, crazy, Capuano? What, do you have tinfoil wrapped around your head?’ And I was like, ‘Well, no. But if I did, it’s still real.’ ”

Others welcome these forays into an emotion-sensing future. “I do believe that if we have information about your emotional experiences we can help you be in a more positive mood and influence your wellness,” Rana el Kaliouby, CEO of Affectiva, an emotion measurement start-up, recently told The New Yorker. She conceives of a world in which firms can capture how you relate to a product and reward you for it. “So if you set a goal to run three miles and you run three miles, that’s a moment. Or if you set the alarm for six o’clock and you actually do get up, that’s a moment.” Creepy or exciting—it’s up to you to decide.

Kaliouby predicted: I think that, ten years down the line, we won’t remember what it was like when we couldn’t just frown at our device, and our device would say, ‘Oh, you didn’t like that, did you?’ ”

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