Here are nine puzzling illusions where you brain tells you one thing but your eyes can’t decide what to think. In some cases your brain can actually tell your eyes what they are seeing.

The first is a very old illusion called ‘Duck or Rabbit’. This drawing by Joseph Justrow appeared in the October 1892 issue of Fliegende Blätter, a German humour magazine. It was captioned (in German) “Which animals are most like each other?” with “Rabbit and Duck” written underneath.

There is an interesting new take on this puzzle which was discovered in 2017.

2. This is an easy puzzle to make. Cut a strip of paper, hold the ends round to make a ring, twist one end and stick the ends together. Now you have the famous Möbius Band whch your can see has two sides but actually has only one side.
August Ferdinand Möbius described it in 1858 but it is said to be found in a Roman mosaic from the third century CE.

To demonstrate the anomaly, imagine a ball rolling round the band, (perhaps it’s magentic and the ball is made of iron). This clearly shows that the band has only one side!

3. A Swedish artist called Oscar Reutersvärd drew this apparently endless staircase in 1937, later copied by Penrose and Escher.

Here is a page showing more of his drawings and this is a cute animation to demonstrate the impossible.

4. This is another classic illusion called Rubin’s Vase devised by a Danish psychologist Edgar Rubin and published in 1915. Do you see a vase or the silhouette of a person and its mirror image?

In 2021 Harold Davis produced this neat demonstration, using his own face which shows the faces that you only see in silhouette and the vase.

5. This image of a pirouetting dancer was created in 2003 by Japanese web designer Nobuyuki Kayahara. You can see her spinning both to the left and to the right as you look and your brain works it out.

This should make it clear. The identical girls on each side are marked to show them clearly spinning - in opposite directions.

6. This is the Ebbinghous Illusion first published in 1901. Do you see the red spot growing as it crosses the screen?

Actually no, it’s the blue spots changing size, the red spot stays the same as you can see.

7. This moving underground train is a new illusion; is it coming into the station or leaving?

Look into the tunnel entrance and think about it and the train may well instantly change direction.

8. An unusual illusion that everyone should see a first glance. I call it the Look-Away Illusion. When you look at the red spot you can see that the ring of black and white dots around it is turning counterclockwise. But now look at the yellow spot and out of the corner of your eye you will see the ring is now moving clockwise!

The explanation is that your peripheral vision sees the clockwise pattern movement inside the black and white dots more acutely than your central vision which pays more attention to the spatial movement of the dots circling the red spot. Peter B. Meilstrup at the University of Washington is the expert on this.

Here is a more artistic version of the same effect. The ferris wheel turns clockwise and counterclockwise depending where you look.

9. This is a puzzle and an illusion. Can you eat a square of chocolate and still have a whole bar left? Of course you can!

There is always one more illusion to see. This goes by the dull title of the Müller-Lyer Illusion but it is actually interesting.