These days, you can hop on the Internet and buy yourself a consumer-grade brain scanning device for just a few hundred dollars. Technically, they're called brain computer interfaces, or BCIs. As these devices develop, researchers are thinking a few steps ahead — they're worried about how to keep marketers from scanning our brains.

The technology, which is basically headgear that senses electrical patterns in your brain, can tell if you're excited, relaxed or focused. Fed into a computer, that brain wave information can be used for any number of applications. One of the most popular ideas is to use the brain as a "third hand" to control video games. Believe it or not, the second neurogaming expo was held recently in San Francisco.

"It's happening somewhat faster than we thought," says Howard Chizeck, a professor of electrical engineering at the University of Washington. "A couple of the new products that have shown up are already along the pathway that I think we thought were a couple of years away."

He believes we're at the edge of a boom in BCI-mediated products, and he's in a hurry to get out in front of the technology's potential threat to privacy. He's working with graduate students Tamara Bonaci and Jeffrey Herron to study how invasive these brain sensors could become.

What?! No... Just no. Millennials, really???