We humans absolutely love to get tricked – at least by illusions, that is. Our brains evolved with a thirst for knowledge. Anytime we learn something new, or encounter a situation that forces us to use our brain in an unexpected way, it triggers a sense of excitement. That’s why things like the “Blue/Gold” dress and other optical illusions gain so much viral traction online.

Take the image below, for example:

Photo Credit: David Novick

Created by Professor David Novick from the University of Texas at El Paso, this particular illusion has been doing the rounds online and stumping people everywhere. It’s based on the Munker-White’s Illusion, which is used to demonstrate the imperfection in our perception of color. When you look at the image from far away, the circles all look like they’re different colors. Seen up close, however, it’s clear that they are all the same.

This is because when you place a solid-colored shape behind bars of different colors, those bars begin to influence the way we see what’s between them. Our brain is trying to fill in the gaps with whatever makes the most sense. That’s why a pink circle can look like it’s tinted with shades of green, purple, or yellow.

Interestingly (and somewhat troublingly), a recent Harvard study found that colors might be even more subjective than we think. Researchers found that participants were pretty terrible at telling blue and purple dots apart, and can even change their minds about what they saw.

It just goes to show: seeing isn’t always believing.