Mental Floss
OPTICAL ILLUSION

How Many Different Colored Eyes Are in This Optical Illusion? Fewer Than You Might Think

Ellen Gutoskey
Go ahead, count the colors.
Go ahead, count the colors. / Lenstore
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UK-based contact lens retailer Lenstore is bringing new meaning to the phrase optical illusion with an image that asks a seemingly simple question of people who can perceive hues without any limitations: How many different colored eyes do you see in the image above?

At first glance, you might say 20, i.e. every single eye is a separate shade. Or maybe you think the red one in the top right corner is close enough to the red one in the bottom right corner to be the same; or the teal one in the top left corner matches the middle eye in the second row. Even if you manage to pinpoint another pair or two, your final count will still be way over the correct total.

lenstore munker-white optical illusion with 20 eyes
It's a trick question. / Lenstore

This is because there are actually only five different colors: one for every column. In other words, the three eyes directly below the brown eye in the top row aren’t purple, green, and reddish-orange—they’re the exact same hue as the brown one above.

The mind-bending picture is an example of what’s known as the Munker-White illusion. In the mid-20th century, according to Live Science, psychologist Michael White studied how overlaying black and white lines on a shape can change our perception of how light or dark the shape itself is. Hans Munker then experimented with altering the colors of the shapes and lines to manipulate our perception even further. David Novick, a professor of engineering education and leadership at the University of Texas at El Paso, told Live Science that our perception gets warped because “we perceive the shapes with more detail and the colors with less detail … the color sort of bleeds over, or assimilates, to adjacent spaces.”

As Lenstore points out, the illusion gets weaker the more you zoom in—as your eyes have an easier time distinguishing the boundaries between the lines and the shape behind it. Feel free to experiment with your device’s zoom-in settings (or break out a good old-fashioned magnifying glass) to help your peepers see the light.

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