Try this: First, stare straight at the screen so both the head-gaze and eye-gaze arrows point directly forward. Now, without moving your head, glance left, right, up, and down—the slim eye-gaze arrows will swing while the thicker head-gaze arrow stays put. Next, keep your eyes fixed on one spot but slowly turn or nod your head; you’ll see the head-gaze arrow shift while the eye-gaze arrows try to stay on target. Exploring these moves side-by-side lets you see how the system separates where your head is aiming from where your eyes are actually looking.