One of the coolest results involved predicting a user was going to click on something before they actually did. That was a ton of work and something I’m proud of. Your pupil reacts before you click in part because you expect something will happen after you click. So you can create biofeedback with a user's brain by monitoring their eye behavior, and redesigning the UI in real time to create more of this anticipatory pupil response. It’s a crude brain computer interface via the eyes, but very cool. And I’d take that over invasive brain surgery any day.