Optical Illusion: What is It?

optical illusion, Florida Eye Specialists and Cataract Institute

Now you see it, now you don’t. Optical illusions (or ambiguous images) can leave you wondering if your eyes are deceiving you. You squint and stare at that staircase that’s going up. Or is it going down? How about that strange psychedelic pattern? You could swear it’s moving. Are your eyes playing tricks on you?

No. Your brain is. These illusions are caused by your brain’s misinterpretation of images. Your perception of an illusion is more dependent on how your brain processes information than how your eyes present that information. Find out what optical illusions are and what makes them so baffling:

WHAT ARE OPTICAL ILLUSIONS?

According to Michael Bach, a vision scientist, and professor of neurobiophysics at the University of Freiburg Eye Hospital in Freiburg, Germany, “Optical illusions are a mismatch between the immediate visual impression and the actual properties of the object.” Optical illusions aren’t malfunctions of the eyes or brain. They’re a disagreement between your eyes and your brain.

HOW DO OPTICAL ILLUSIONS WORK?

Optical illusions happen when your brain struggles to connect what it’s seeing with what it expects to see. In one-tenth of a second, your visual system sees, transmits, and processes images. Your brain strives to organize this information by defining borders, analyzing contrasting areas, sorting colors, and even guessing, based on experience, what is needed to fill the blanks. It’s constantly predicting what will happen next, which is its way of protecting you.

This process usually works, but sometimes your brain gets confused and can’t logically assemble this information. The result? An optical illusion.

ARE THERE DIFFERENT CATEGORIES OF ILLUSIONS?

Yes. Visual illusion is an umbrella term for all illusions. There are specific categories of illusions:

• Ambiguous Illusions – Pictures or objects that toggle between alternative interpretations. The Rubin’s Vase is an ambiguous illusion.

• Distorting Illusions – These illusions distort length, position, curvature, and size. A classic example of a distorting illusion is the Ponzo Illusion, in which two identical lines look like they’re different lengths.

• Paradox Illusions – Paradox illusions would be impossible in three dimensions. However, they look believable in two-dimensional drawings. These illusions rely on the brain’s misunderstanding that two edges must always connect. A famous example of a paradox illusion is “Ascending and Descending,” by M.C. Escher.

CAN OPTICAL ILLUSIONS HARM MY EYES?

According to the Mayo Clinic, optical illusions won’t hurt your eyes unless you look at them for a long time and develop mild eyestrain. However, if you experience double vision or pain, it may be a sign of a serious condition. Florida Eye Specialists and Cataract Institute, Tampa Bay’s leader in complete eye care, can give you the reassurance of a trusted friend while expertly assessing and treating your condition.

ARE THERE REAL-LIFE OPTICAL ILLUSIONS?

There are real-world optical illusions. Some can be dangerous, and some are beneficial. Visual illusions can affect pilots in-flight. They may see a false horizon while airborne or a narrow runway when landing. Pilots are trained to identify and disregard this visual misinformation so that they can fly and land their planes safely.

CAN OPTICAL ILLUSIONS BE HELPFUL?

Some illusions actually help thwart any danger. An optical illusion has been implemented as a safety measure on Chicago’s Lake Shore Drive to control motorists’ speeds on a notoriously dangerous curve. The road appears to narrow from 16 feet wide to 8 feet wide. This illusion tricks drivers into slowing down to better navigate a tight-looking road.

Optical illusions have an important spot in research, as well. According to Susana Martinez-Conde, director of the laboratory of visual neuroscience at Barrow Neurological Institute in Phoenix, Arizona, “Optical illusions are important tools in visual research to help us understand how visual processing works in the normal brain and also in the diseased brain.”

DO ANIMALS USE OPTICAL ILLUSIONS?

Animals are just as adept as humans are at visual trickery. Fiddler crabs woo the ladies with something called the Ebbinghaus Illusion. This effect allows males to elevate their perceived sex appeal by hanging out with less attractive competitors.

Hummingbirds can’t hover in front of a flower placed before a rolling, striped background. This gives them the false impression that the flower is moving.

A zebra’s striping also falsely conveys movement, making it difficult for predators to correctly time their attack.

Optical illusions make us second guess what’s real and what’s not. They may even make us wonder if there’s a problem with our vision. However, illusions take place in our brain, not our eyes. If you’re still concerned about your eyesight, the compassionate, highly experienced professionals at Florida Eye Specialists and Cataract Institute will apply the most advanced technologies to address your condition. Contact us now for an appointment and see what you’ve been missing.

Please note that not all of the information in this article will work for everyone and that this article is not a substitute for actual in-person medical treatment.