In that image above, do the lines look both like a zigzag and like a curve? Well, you might be surprised to learn they’re actually all curvy.
This awesome optical illusion was revealed by Kohske Takahashi from Chukyo University in Nagoya-Shi, Japan. The findings were published in a paper in the journal i-Perception.
In the illusion, it looks like the lines in the top left white section and the bottom right black section are all curvy. However, in the middle section, a lot of the lines appear like zigzags.
Well, we’re afraid to say that your mind is playing tricks on you, and the reason isn’t 100% clear.
In an email to IFLScience, Takahashi said the answer was simple: evolution. “Our eyes may have been adapted to detect corners more efficiently than curves,” he said.
He elaborates in his paper, which tasked university students with trying to figure out if the liens were curvy or zigzags. It was noted that the lighting wavy line needed to be reversed against the turning points to make this effect happen.
The cause may be due to the “impaired curvature detection” in our eyes, notes Takahashi in the paper. “In the present study, the change of luminance contrast resulted in the percepts of segmentation, which would disrupt the curvature detection,” he writes.
“We propose that 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 system.”
That’s a sciencey way of basically saying your eyes suck, and they can’t properly work out the difference between a slight curve and a zigzag when the background color changes slightly.
It’s an incredibly interesting optical illusion for sure, and one that we still don’t quite understand. It shows that we’re not only bad at telling when a line is bent, but we’re also pretty bad at corner detection too.
“Further investigation of these unexpected effects will allow us to extend the understanding of the mechanisms of corner detection,” adds Takahashi.