This optical illusion plays tricks on your brain

Check out these mysterious optical illusions that affect our visual perception.

This optical illusion plays tricks on your brain

If you look at the cross in the middle for at least 10 seconds, colorful spots on the sides will begin to fade away, courtesy of the Troxler effect.

  • Troxler's effect or "fading" causes images to disappear from your field of vision.
  • Scientists don't have a full understanding yet of how this works.
  • The effect is linked to the way neurons are adapted by the visual system.


Why do we some times see things that aren't there? Delighted by stories of vengeful ghosts and spirits, we largely assume there's a world outside of our regular field of vision. Whether it's inhabited is certainly debatable but the curious psychological condition called Troxler's Fading or Troxler's Effect may explain one optical illusion.

This effect is named after a Swiss physician and philosopher Ignaz Paul Vital Troxler (1780-1866), who discovered it in 1804. It is essentially a trick of perception that describes what happens if you fix your gaze upon a single point in the visual field. It doesn't even have to be for a long time – 10 seconds would do. That can make images and colors disappear from your peripheral vision.

THE LILAC CHASER

"Lilac chaser".

Look at the black cross at the center of the image and the spots in this "lilac chaser" illusion will fade away in a few seconds. A grey background and the cross will remain unless you are among those who will also see a moving blue-green spot. You might even notie a bunch of green spots when you move your eyes away after a while.

HOW DOES IT WORK?

Research indicates the effect is related to how neurons important for perceiving stimuli are adapted by the visual system. Unchanging stimuli will eventually disappear from our awareness while our mind will fill the areas where they used to be with the background information (or color). A "sensory fading" or "filling-in" is linked to saccades – involuntary eye movements that happen even when the gaze appears settled. If we fixate on a point, an unmoving image or scene would fade from view in a few seconds thanks to the "local neural adaptation of the rods, cones and ganglion cells in the retina," explains the Illusions Index.

The effect is made stronger if the stimulus image is low contrast or blurred.

While studies showed the effect doesn't only occur in the eyes but partially in the brain, there's not yet a definitive explanation for everything involved in this unusual visual phenomenon.

Another example image of the Troxler effect. Look at the center of the image for about 10 seconds.

And another fun example:

Malcolm Gladwell live | How to re-examine everything you know

Join Radiolab's Latif Nasser at 1pm ET today as he chats with Malcolm Gladwell live on Big Think.

Big Think LIVE

Add event to your calendar

AppleGoogleOffice 365OutlookOutlook.comYahoo


Keep reading Show less

There are 5 eras in the universe's lifecycle. Right now, we're in the second era.

Astronomers find these five chapters to be a handy way of conceiving the universe's incredibly long lifespan.

Image based on logarithmic maps of the Universe put together by Princeton University researchers, and images produced by NASA based on observations made by their telescopes and roving spacecraft

Image source: Pablo Carlos Budassi
Surprising Science
  • We're in the middle, or thereabouts, of the universe's Stelliferous era.
  • If you think there's a lot going on out there now, the first era's drama makes things these days look pretty calm.
  • Scientists attempt to understand the past and present by bringing together the last couple of centuries' major schools of thought.
Keep reading Show less

Ever wonder how LSD works? An answer has been discovered.

UNC School of Medicine researchers identified the amino acid responsible for the trip.

Credit: Motortion Films / Shutterstock
Surprising Science
  • Researchers at UNC's School of Medicine have discovered the protein responsible for LSD's psychedelic effects.
  • A single amino acid—part of the protein, Gαq—activates the mind-bending experience.
  • The researchers hope this identification helps shape depression treatment.
Keep reading Show less

Scientists uncover the brain circuitry that causes mysterious dissociative experiences

A team of researchers have discovered the brain rhythmic activity that can split us from reality.

Mind & Brain
  • Researchers have identified the key rhythmic brain activity that triggers a bizarre experience called dissociation in which people can feel detached from their identity and environment.
  • This phenomena is experienced by about 2 percent to 10 percent of the population. Nearly 3 out of 4 individuals who have experienced a traumatic event will slip into a dissociative state either during the event or sometime after.
  • The findings implicate a specific protein in a certain set of cells as key to the feeling of dissociation, and it could lead to better-targeted therapies for conditions in which dissociation can occur.
Keep reading Show less
Scroll down to load more…
Quantcast