via How We Drive:

" “Let us consider for a moment you are driving down the road and approaching a signalized junction. The scene in front of you is a dynamic one and is constantly evolving. The light is at present green but of course this may change. The intersection is also currently clear, but of course this may also change. Now let us run the scenario forward. As you approach the actual crossing, the visual angle between the traffic light and the forward view across the junction begins to increase. There comes a point in time where one cannot see both together. This is not a divided attention issue or one or foveal versus peripheral field of view, it is a simple question of structural interference, the driver’s eye cannot see both at the same time. The design efforts of traffic engineers in terms of sight lines, seek to reduce any such occurrences of ambiguity, and on most occasions they are very successful. However, let us consider this example as one of inherent ambiguity. Where is the driver to look? If you look at the light to see a possible change, one cannot look at the intersection and vice versa. The pragmatist will say that by the time the light changes, the junction should be free. However, the simple fact is that driving presents many such ambiguous situations in which, whatever “correct” action one is actually accomplishing, there is another equally “correct” action that one must neglect. What of distraction in such circumstances? Can we say the driver involved in a collision in such circumstances is distracted and is not driving with due care and attention?”

That’s one of the many interesting bits of a paper by P.A. Hancock, M. Mouloua, & J.W. Senders, “On the philosophical foundations of driving distraction and the distracted driver,” in a recent book titled Driver Distraction: Theory, Effects, and Mitigation. "

I have always considered the most dangerous driver to be one who knows he is getting to the end of a green or yellow light and is desperate to make it (and it seems as though most drivers are). Their eyes are on the light only and not on the road. However, I find it hard to believe that it's impossible for a driver to look at the intersection and the light at the same time.