homehome Home chatchat Notifications


Flies get mesmerized by optical illusions too -- and this could explain the phenomenon

Although the lineages of flies and humans diverged half a billion years ago, we're both tricked by the same optical illusions.

Tibi Puiu
August 24, 2020 @ 10:04 pm

share Share

In this stationary image, viewers should see the circles rotating in different directions. Credit: A. Kitaoka,  R. Tanaka.

Some optical illusions can be truly mind-boggling and mystifying. But what’s even more intriguing is the neurological mechanism that underlies them. In a new study, researchers found that a fly’s eyes can also be tricked by optical illusions similarly to humans, perceiving stationary images as in motion. The researchers’ findings could explain why this phenomenon occurs.

“It was exciting to find that flies perceive motion in static images the same way we do,” Damon Clark, associate professor of molecular, cellular and developmental biology and of physics and of neuroscience at Yale University, said in a statement.

Clark and colleagues decided to mesmerize flies with optical illusions because the insects are very well studied and their tiny brains facilitate tracking the activity of neurons involved in the visual system.

Using an optical illusion similar to the one embedded in this article, researchers measured the behavior of lab flies. They found that the insects could indeed perceive motion in an otherwise static image, just like humans do.

When they sense motion, flies instinctively turn their bodies toward the object in motion. This is what also happened with perceived motion when presented with the optical illusions, which is how the researchers could tell for sure that flies could sense them.

By zooming in on specific neurons involved in detecting motion in the fly brain, the researchers detected a pattern of neural activity triggered by the static pattern.

When two specific types of motion-detecting neurons were turned off, the illusion effect disappeared entirely. What was intriguing is that when only one of the two neurons was turned off, the flies perceived the motion of the illusion in the opposite direction than they did with both neurons active.

Judging from these findings, the authors of the new study conclude that optical illusions arise from small imbalances in how different types of motion-detecting neurons contribute or fail to respond to certain imagery.

“The last common ancestor of flies and humans lived a half billion years ago, but the two species have evolved similar strategies for perceiving motion,” Clark said. “Understanding these shared strategies can help us more fully understand the human visual system.”

The findings were reported today in the Proceedings of the National Academy of Sciences.

share Share

Gardening Really Is Good for You, Science Confirms

Gardening might do more for your health than you think.

The surprising health problem surging in over 50s: sexually transmitted infections

Doctors often don't ask older patients about sex. But as STI cases rise among older adults, both awareness and the question need to be raised.

Kids Are Swallowing Fewer Coins and It Might Be Because of Rising Cashless Payments

The decline of cash has coincided with fewer surgeries for children swallowing coins.

Horses Have a Genetic Glitch That Turned Them Into Super Athletes

This one gene mutation helped horses evolve unmatched endurance.

Scientists Discover Natural Antibiotics Hidden in Our Cells

The proteasome was thought to be just a protein-recycler. Turns out, it can also kill bacteria

Future Windows Could Be Made of Wood, Rice, and Egg Whites

Simple materials could turn wood into a greener glass alternative.

Researchers Turn 'Moon Dust' Into Solar Panels That Could Power Future Space Cities

"Moonglass" could one day keep the lights on.

Ford Pinto used to be the classic example of a dangerous car. The Cybertruck is worse

Is the Cybertruck bound to be worse than the infamous Pinto?

Archaeologists Find Neanderthal Stone Tool Technology in China

A surprising cache of stone tools unearthed in China closely resembles Neanderthal tech from Ice Age Europe.

A Software Engineer Created a PDF Bigger Than the Universe and Yes It's Real

Forget country-sized PDFs — someone just made one bigger than the universe.