p159fig04.36 Graffiti art by Banksy exploits properties of amodal boundary completion and spatial impenetrability.<BR>|| p159c1h0.75 perceptual psychologist Nava Rubin "... When the wall is smooth, Banksy leaves the regions previously covered by stencil unpainted, relying of observers' perception to segregate figural regions from the (identically colored) background. But when the wall is patterned with large-scale luminance edges - eg due to bricks - Banksy takes the extra time to fill in unpainted figural regions with another color (Rubin 2015). ..."