Scott discusses the phenomenon of dark shapes being prominent in paintings where the majority is light valued. After presenting the concept, he does a demonstration painting of a winter road in gouache using a limited palette.
If the majority of your painting is light, the viewers eye will seek the dark shapes.
Small, fine dark shapes (especially ones in isolation) will attract the viewers eye.
Patterns of dark shapes can be added and used to direct the viewers eye toward the center of interest.