Looking at how various artists have made use of positive and negative space, I’ve found it useful to focus on the background of paintings and look at how the negative space around the main ‘positive’ objects help ring those objects to life. Often, strong and flat colours are used to ‘throw out’ the objects in focus, but sometimes, as in Patrick Caulfield’s work, the background ‘negative’ space colour is actually repeated in the positive space.
Above, Pablo Picasso, Weeping Woman (1937), Brent Harris, Study for ‘Swamp’ (no. 1) B (1999), Vincent Van Gogh, Blooming Almond Branch (1890), Patrick Caulfield, Bowl and Fruit (1979), Gary Hume, Untitled 9 (from Sister group) (2009) and Bouquet (2009), Eric Thake, An Opera House in Every Home (1972), and Juan Sanchez Cotan, Still Life with Quince, Cabbage, Melon and Cucumber (1602).
Negative space is clearly not only used as a device to emphasise the main objects, but also to frame and add balance to the composition.
Ruth Beech - Mindful Movement, Meditation and Art 