When pedestrian accidents happen at night in Pennsylvania, drivers often claim that they never saw the people before hitting them. The most obvious reasons for this are that it's dark, visibility is reduced, people and other objects become dim, and people who are wearing dark clothing blend right in. However, there are a few other issues as well.
One is that drivers usually don't look right at pedestrians, instead picking them out with their peripheral vision. If a pedestrian is walking to cross the street and the driver is looking in a straight line ahead, as he or she has been taught to do, the pedestrian comes slowly into this range. When it's dark, peripheral vision is drastically reduced, making pedestrians seem to "jump" out of nowhere.