Changing Your Selection Backdrop
When you’re making a complex selection, seeing the selection on the right backdrop helps a lot. When you’re in the Refine Edge dialog (Select>Refine Edge), you can switch to different backdrops for viewing your selection. Just press B for black, W for white, and K for a black-and-white view. There are others, but those are the three you’ll use most.
by Matt Kloskowski