Afterimage: Now You See it, Now You Don’t

In case you can’t tell, we love everything about optical illusions. Perhaps one of the best parts, though, is when you can catch an illusion happening naturally. One of the most fun aspects of the illusion we’re talking about in this post is that it occurs naturally all the time. We’ve said it about other illusions before, but this is one that you have DEFINITELY experienced with your own two eyes. That’s because all you need is your own two eyes in order to see it. That’s right, today we’re talking about Afterimage.

If you’re not familiar with the concept of Afterimage, it is an illusion where an image continues to appear even when you stop looking at the actual image. If you’ve ever looked into a light for too long, and then seen black dots seemingly burned into your vision when you looked away, you’ve experienced Afterimage. This is a natural effect that occurs because of our color receptors. The fun begins when artists and illusionists start using Afterimage to create fun images and really trick the brain.

The lilac chaser afterimage optical illusion for the MOI NYC blog.
The lilac chaser afterimage illusion. Focus on the black cross in the center and watch the illusion unfold!

The Two Main Types of Afterimage

There are actually two types of Afterimage. These are positive and negative Afterimage. Both occur in the same way but create a different effect.

Positive Afterimage is when the colors of the original image are retained in the illusion. This is often created artificially but does occur naturally sometimes. Most often, this will occur naturally in the first 500 milliseconds of looking away from the original image. After this, the colors will reverse and become a negative illusion.

Negative Afterimage is when the colors of the original image are reversed. Negative is the version of this illusion that you are most likely to encounter naturally. Positive afterimage has to be manufactured or created on purpose. When you are looking at a naturally occurring stimulus and you look away, the colors of the original image are going to be reversed in the after effect. For example, an image that is red will appear green in its afterimage.

How it Works

Positive and negative afterimages have slightly different explanations, but because negative is the one that you are most likely to experience, we’re going to focus mainly on that one.

Unlike a lot of illusions that we talk about here on the MOI NYC blog, there is actually a thorough explanation for how afterimage works. Because it’s so prevalent, scientists have been studying it for a long time.

Negative afterimage can be explained with the opponent-process theory of color vision. This theory states that our brains process color using three receptors- red/green, blue/yellow, and black/white. For example, if you look at a red square the red receptor is stimulated, but when you look away there is no longer a red stimulus present so your brain shows a green afterimage.

Popular Afterimage Illusions

Afterimage is most often used to create portraits of celebrities. You might be most familiar with the “Lilac Chaser” gif at the top of the page, or the image of Amy Winehouse pictured below.

An afterimage illusion of Amy Winehouse created by Dimitri Parant. Used for the Museum of Illusions NYC blog.
An afterimage illusion of Amy Winehouse by Dimitri Parant. Focus on the white dot in the center for about 30 seconds and then look away.

If you concentrate on the dot at the center of the image for about 30 seconds, you will see a full-color floating image of Amy when you look away. Pretty cool, right?

If you’re as passionate about illusions as we are, or you’re ready to start dipping your toes into this world of real-life magic, be sure to plan your visit to the Museum of Illusions NYC. Click here to book your ticket. We can’t wait to show you around!