Keep your eyes on the red dot. After the black and white dashed outlines have vanished, does the entire square look gray to you?  

Look again, but now move your eyes. The dark gray square that follows the dashed outlines is clearly visible as long as you do not fixate the red dot. Read more:

Cox, Lowe, Blake & Maier (2014) Sustained Perceptual Invisibility of Solid Shapes following Contour Adapation to Partial Outlines.

Consciousness & Cognitions [in press]


Fixate on the center of the grid for some minutes. You will perceive spontaneous alternations in which either the horizontal or vertical lines fade from your view. 

Note that the center does not get spared from the illusion. The longer you stare, the more striking the effect of this visual 'pattern rivalry'. Read more about this illusion:

Maier et al. (2005) Global competition dictates local suppression in pattern rivalry.

Journal of Vision 5(9):668-677


Stare at the display on the left for several minutes. Do you see the sphere changing directions? Note how these reversals cannot be stopped no matter how hard you try.

Now look away for a second and look back repeatedly. Surprisingly, this will prevent any further perceptual changes from happening. Read more about 'perceptual stabilization':

Maier et al. (2003) Perception of temporally interleaved ambiguous patterns.

Curr. Biol. 13:1076-1085

© Vanderbilt University 2014