My Brain Knows My Password: Some people keep passwords in books or on sticky notes, but what would you do if you never had to remember another password? A new technology claims to be able to prompt your brain directly for a password without your interaction. according to Popular Science it's, "based on an idea known as implicit learning, in which the brain subconsciously learns a pattern without consciously recognizing it."
subjects were implicitly taught a pattern by playing a video game. Weeks later their behaviors indicated they could recall the pattern, but their conscious mind could not. "The idea could form a security scheme in which an authorized person is embedded with a sequence in an initial session. Previous studies have shown that sequences learned implicitly simply can’t be recalled or understood by the brain, so there’s no way the person could willingly or unwillingly give up their authenticating password (in the future)." via Popular Science