Valve has a history of experimental hires, like when it brought on an economist to examine in-game economies. The company has now taken in Mike Ambinder, an experimental psychologist who is tasked with researching biofeedback.

VentureBeat reports that Ambinder talked at a session during the NeuroGaming Conference and Expo last week. He said that the company has conducted experiments that measure factors like players sweat, player calmness, and eye tracking. The sweat levels fed data into Left 4 Dead to modify the game experience, while the player's calmness might impact how much time they have to complete an objective. It also created a version of Portal 2 that you could control with your eyes, since they can move faster than your hands.

The measurements can come from readings of heart rate, brain waves, pupil dilation, body temperature, and even facial expressions. Ambinder said that the biofeedback could potentially be used to find better multiplayer matches, create game profiles, and make better peaks and valleys of content.

We've heard before that Valve was looking into biometric controllers, so bringing in a professional in the field makes perfect sense. So far, though, it's only in the testing phases, and Valve hasn't made any mention of actual hardware plans.

"One thing we are very interested in is the notion of biofeedback and how it can be applied to game design," Ambinder said. "There is potential on both sides of the equation, both for using physiological signals to quantify an emotional state while people are playing the game. The more interesting side of the equation is what you can do when you incorporate physiological signals into the gameplay itself. If we could start tapping into that, we could tap into a whole wealth of data."