Students from MIT have created a prototype device, dubbed AlterEgo, that can recognize the words you mouth when silently talking to yourself—and then take action based on what it thinks you’re saying.

Arnav Kapur, a master’s student at the MIT Media Lab—a division of the Massachusetts Institute of Technology that focuses on the intersection of people and technology— and author of the paper, stresses that the device doesn’t read thoughts or the random, stray words that just happen to pass through your mind. “You’re completely silent, but talking to yourself,” he says. “It’s neither thinking nor speaking. It’s a sweet spot in between, which is voluntary but also private. We capture that."