By Jonny Lupsha, Wondrium Staff Writer
A nonprofit organization’s Best Illusion of the Year Contest has a winner for 2020, Science Alert reported. The award went to a 3D staircase, which, when rotated, can appear to be going up or down in either direction. Perception illusions happen when our brains deceive us.
According to Science Alert, there is a small thing to celebrate at the end of the vexing year of 2020. The Neural Correlate Society, a nonprofit organization promoting interest in science, has run its “Best Illusion of the Year Contest” and announced a winner. “It is indeed a worthy mind-boggler, taking one of the best-known traditional 2D optical illusions and realizing it perplexingly in three-dimensional space,” the article said.
“Designed by the mischievous mathematician Kokichi Sugihara—a celebrated Japanese illusionist and repeat winner—this is called the 3D Schröder Staircase.”
Illusions of perception happen when our brain perceives something as existing one way but then it ends up being another way.
How Optical Illusions Work
“All types of illusions, by definition, are times when the brain constructs sensory perception in an incorrect way—it’s a misperception of reality,” said Dr. Steven Novella, Assistant Professor of Neurology at the Yale School of Medicine. “Generally, objects in our world appear to be stable and they appear to be accurate with respect to reality, which psychologists refer to as constancy.
“Optical illusions, by definition, represent an exception to constancy, when objects are neither stable nor they do not accord with reality. There is some kind of internal inconsistency or paradox in what we think we are seeing.”
Dr. Novella said this happens because the brain must make assumptions about the world as it perceives it. Most of the time, those assumptions are correct, but optical illusions happen when they aren’t correct.
Dr. Novella said that constructed illusions are designed to specifically exploit ways that our brain perceives reality. One kind of constructed illusion is called a perspective illusion.
“Perspective illusions all exploit the ways in which our brains can construct three-dimensional images out of two-dimensional input,” Dr. Novella said. “Visual input is two-dimensional. Our retinas are a flat-curved surface and the brain has to then infer from that two-dimensional input [into] a three-dimensional world, [accounting for] relative size and distance and movement, for example.
“Mostly, [the brain] does this with stereoscopic vision, the fact that it has input from two different eyes that it can compare. Even with just input from one eye, the brain can make reasonable inferences about the three dimensionality of the world around it.”
Dr. Novella said that it’s important to remember that three-dimensional images are constructions—something that’s happening in our brains—and that it’s important to remember that in order to understand how illusions work. Classic examples of “ambiguous stimuli” illusions include the 2D drawing of a transparent 3D cube, in which it’s difficult to determine which square-shaped side of the cube is the “front” and also a spinning silhouette that may look like it’s rotating in either direction.
As our brains try to reconcile this conflicting information, we can still enjoy the brain-teasing aspects of solving optical illusions.
Dr. Steven Novella contributed to this article. Dr. Novella is Assistant Professor of Neurology at the Yale School of Medicine. He earned his MD from Georgetown University and completed his residency training in neurology at Yale University.