People typically hold the iPhone closer to their face than they hold their laptop. Since accuracy in eye tracking depends on the angle between the calculated ga

People typically hold the iPhone closer to their face than they hold their laptop. Since accuracy in eye tracking depends on the angle between the calculated gaze vector and the true gaze vector, this means that error will be reduced. The amazingly high pixel density on the iPhone 4 means that that the calculated gaze focus may be more pixels away from the real point - but we're working on some ways to compensate for that.