How "After Imaging" Tricks Our Eyes Into Seeing Color

Trevor English

If you are a fan of optical illusions, then you ae probably familiar with the trick that involves staring at a dot on a black and white image. After a little while, the image changes to another solid color like sepia or even inverted colors, but your eyes see the image like normal. This illusion takes advantage of how your eyes process visual cues and makes you see things that really aren't there. Learn a little more about this process, called 'after imaging' in the video below.

Essentially what is happening in these illusions is when you look at them for extended periods of time, your eyes  get fatigued and tired. The cones in the back of your eyes allow you to process and perceive color. As you look at a certain color for a long time, that cone becomes tired and stops sending repetitive signals to the brain. When the colors are removed, the cones that aren't tired continue sending signals and your brain processes colors that aren't really there.

Our perception of color is actually a little skewed, especially when it comes to computer screens and digital media. Screens can only create 3 colors, red, green and blue. This means that every color on your page right now is ultimately made up of a combination of these three lights, or pixels. So when you see the color orange on your screen, you really aren't. You are just seeing red, green and blue in different intensities.

after imaging[Image Source: AsapSCIENCE]

While our eyes are some of the most complex in the world, shortcuts that our brain takes in processing the abundance of information they feed ultimately leaves us susceptible to visual trickery. What are some of your favorite optical illusions?