The "barber-diamond" demonstrates the ability of depth-cues to influence our interpretation of moving features and hence of perceived direction of motion. To appreciate this illusion, click on BARBER-DIAMOND DEMONSTRATION and view the resultant animation through a pair of red-green anaglyph glasses (red lens on right eye). The leftward motion should alternate between upwards and downwards.
Half the dots oscillate from top-left to down-right and back, the other half from top-right to down-left and back. Which axis of motion do you see most?
This depends upon the depth-ordering of the flankers. It is much easier to see the dots oscillate along the axis of the NEAR flankers.
