[quicktime]http://anstislab.ucsd.edu/files/2013/10/BlurSharp1.mov[/quicktime]

A flickering contour is a much more effective adaptor than a flickering blurred surface. Gaze at the center spot and view the flickering adapting stimuli, on the left a ring and on the right a blurred surface. Following adaptation, the left test disk disappears while the right disk remains visible.  Adapting to the flickering contour leads to contour erasure, while adaptating to the surface does not.