GazeHawk is a YC startup that does eye tracking using webcams. More about it here: http://www.gazehawk.com/ http://www.gazehawk.com/ Presumably they got a bunc

GazeHawk is a YC startup that does eye tracking using webcams. More about it here: http://www.gazehawk.com/ http://www.gazehawk.com/ Presumably they got a bunch of people who were willing to participate in the study, then showed them the same screenshot of Reddit and tracked their eyes using their technology.