In studying a picture you can switch your perception to the 'negative spaces', the spaces between things which until then seemed to have merely a supportative role but can now be understood in a positive sense, as having shapes and movements of their own which contribute in an important way to the overall aesthetic effect. A similar effect is present in music where you can pay attention to the intervals of time and pitch and intonation between the positive melodic or motivic elements. In modernist music these easily assume equal importance. The same reorienting of perception can also be applied to thought and more broadly to experience itself except that here it is the very mind that can effect this alternation of gestalt that is made subject to it, and of course also here the trick is so much the more difficult to sustain. It amounts to another approach to what is otherwise referred to as the background consciousness.