Duck Or Rabbit: Why Is This Hundred-Year-Old Optical Illusion The Latest Internet Controversy?

Is it a duck or a rabbit? A 100-year-old optical illusion is now the latest “What Is It” internet controversy, joining the striped dress and the mom-or-daughter on the list of silly things people argue about on the internet.

A hundred years ago (in 1892, to be specific), according to MSN, the duck or rabbit illusion first appeared in a German humor magazine, intended as nothing more than a fun cartoon. It was such a throwaway gag that even the original artist has long since been lost to history.

Unlike “the dress” or the which is the mother, which is the daughter controversies, the duck or rabbit illusion has no right answer. That’s the point. If you look at the left side of the image, you can imagine a duck’s bills. And as your eye scans the image left-to-right, you can see the eye as the duck’s eye and the right edge of the image as the back of the duck’s head. If you look at the right side of the image, you can see the right edge of the image as the front of the rabbit’s head. Looking right-to-left, you see the rabbit’s eye, and then on the far left are the rabbit’s ears.

In other words, your brain sees what it sees.

For turn-of-the-century American psychologist Joseph Jastrow, whether you see a duck or a rabbit, or both, and how quickly you realize there are two images, reveals a lot about your brain. And the faster your brain realizes there are two images and the faster you can switch between the two mentally, the more creative you are.

There’s also a seasonal component to the duck or rabbit illusion – or at least, there is in Europe and North America, where there four distinct seasons and a Christian cultural tradition. Around Easter, for reasons that a moment’s thought should make obvious, viewers are more likely to see a rabbit first. In October, viewers are more likely to see a duck first (is duck a traditional part of the menu during Oktoberfest?).

The duck or rabbit illusion wasn’t exactly forgotten about. It, along with several other hand-drawn and computer-generated optical illusions, can still be found in psychology or art textbooks and websites devoted to optical illusions.

Optical illusions exist because of the complicated relationship between the human eye and the human brain. Your eyes don’t “see” images — they merely gather information to send to your brain, and your brain makes sense of that information. When the information your brain receives is contradictory or ambiguous, it makes its best effort to come up with something meaningful.

The brain’s relationship to the eye is also the reason people sometimes “see” images of Jesus Christ in pieces of toast or statues of the Buddha on Mars when, in fact, there is no Buddha on Mars and Jesus Christ did not manifest in a piece of toast. The phenomenon is called “pareidolia” – that is, the tendency of the human brain to assign meaning to random visual stimuli when no such meaning exists.

Which did you see first, a duck or a rabbit? Share your thoughts in the comments below.

[Image courtesy of Flegende-Blatter-1892 via Wikimedia Commons by Public Domain]