Figure 3: Adelson’s Snake. All of the small diamonds have the same luminance (on screen) or reflectance (if printed). But the top left row of diamonds, which seems to be behind a dark trans- parency, appears much lighter than the bottom left row, which seems to be strongly illuminated. The image on the right hand side (the ‘anti-snake’) shows the basic simultaneous contrast effect for comparison. From Kingdom (2011).