Duck-Rabbit Illusion

Two animals, one outline

The drawing is a single closed outline with an eye. Read the two long lobes on the left as a bill, and you see a duck looking left with its beak slightly open. Read the same lobes as ears laid back along the head, and you see a rabbit looking right, with the small notch on the right of the head as its mouth. The ink is identical either way; the lines simply change jobs.

Most people can switch between the two once they know both are there, but they can't hold both at the same moment. One animal always wins, and when the other takes over, it replaces the first completely.

Why a label reorganises the whole drawing

This flip happens at a higher level than the one in the Necker cube. The cube keeps the same shape and only swaps which face is nearer. Here the brain has to decide what kind of object it's looking at, and that decision reassigns every part at once: the lobes become a bill or ears, the left of the drawing becomes the front of the animal or the back of its head, and the whole figure faces left or right.

Recognition and interpretation aren't separate steps. As soon as "duck" or "rabbit" takes hold, the label shapes how the sparse lines are read, which is why the switch can feel more effortful than the cube's. You aren't just reassigning depth to a shape you've already agreed on; you're recategorising the whole object.

Easter turns it into a rabbit

Because the switch depends on what you expect to see, the figure is easy to bias. Peter and Susanne Brugger showed the drawing to visitors at Zurich Zoo and found that at Easter most people named it a rabbit, while in October most named it a duck (Brugger & Brugger, 1993). The drawing hadn't changed; the season had changed what people were primed to recognise.

The demo above uses the same idea with backgrounds rather than seasons. Look at the bare drawing first and note which animal you see, then put it on the pond and in the meadow. Context doesn't force a reading, but it usually tips the balance.

From magazine joke to philosophy

The earliest known version appeared in the German humour magazine Fliegende Blätter in 1892, captioned with the question of which two animals look most alike. The artist isn't recorded. The American psychologist Joseph Jastrow reprinted it in 1899 in an essay on how the mind shapes what the eye sees, which turned it from a gag into a research example.

Its most famous reader was the philosopher Ludwig Wittgenstein, who used it in Philosophical Investigations to separate "seeing" from "seeing-as". His point was that noticing the rabbit where you saw a duck isn't seeing anything new: nothing on the page has changed, yet the experience has. Rubin's vase and faces and the "my wife and my mother-in-law" drawing work the same way, each flipping between two complete readings of an unchanging image.