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Saturday 9 December 2017

"Curvature blindness" illusion discovered

S.O.T.T: A series of wavy horizontal lines are shown. All of the lines have exactly the same shape - a sine curve. However, half of the lines appear to have a much more triangular, "zig-zag" shape, when they are superimposed on a grey background. This "zig-zag" appearance is an illusion. 
 
As the effect magnitudes are quite strong, unless one carefully stares at the region that looks like a corner, it is hard to find that all lines are physically wavy. Despite the simplicity and effect magnitudes, to the best of our knowledge, no one has reported about this phenomenon.So what's going on here? 

The brain's visual system may default to seeing corners when there ambiguity over whether a line is a smooth curve or not:
The underlying mechanisms for the gentle curve perception and those of obtuse corner perception are competing with each other in an imbalanced way and the percepts of corner might be dominant in the visual systemThe "zig-zag" lines in the illusion are the ones in which the color of the wavy line changes from dark grey to light grey at the 'corners' i.e. the peaks and troughs of the curve. It is only seen against a medium grey background however, suggesting that what matters is that the color of the wavy lines shifts from being lighter than the background, to being darker than it....read more>>>...