OAKLAND, Calif.—In the beginning, people hacked phones. In the decades to follow, hackers turned to computers, smartphones, Internet-connected security cameras, and other so-called Internet of things devices. The next frontier may be your brain, which is a lot easier to hack than most people think.

At the Enigma security conference here on Tuesday, University of Washington researcher Tamara Bonaci described an experiment that demonstrated how a simple video game could be used to covertly harvest neural responses to periodically displayed subliminal images. While her game, dubbed Flappy Whale, measured subjects’ reactions to relatively innocuous things, such as logos of fast food restaurants and cars, she said the same setup could be used to extract much more sensitive information, including a person’s religious beliefs, political leanings, medical conditions, and prejudices.

“Electrical signals produced by our body might contain sensitive information about us that we might not be willing to share with the world,” Bonaci told Ars immediately following her presentation. “On top of that, we may be giving that information away without even being aware of it.”