One of the most important skills a good editor needs to develop is the ability to understand and manipulate the gaze of the audience member. The quality of every cut you make depends on your ability to determine where the audience will be looking before the cut and control where they look too after the cut. Many factors go into this including the emotional content of the scene, the composition, lighting and focus of the shot and the movement of objects within the frame. A lot of the time, this decision is made instinctually and you can usually feel if a cut is smooth or jarring (both have their place), but there are several things you can do to improve your cutting ability. One resource which has only recently developed is technology which can detect where your audience members are looking on the screen and log that information as data. The following video comes from a small audience watching a scene from There Will Be Blood. The circles on the screen represent where in the frame each audience member is looking. If someone maintains there gaze on one spot then the circle grows in size. I hope you find this as interesting and useful as I did.