We like optical illusions for thousands of years. The Romans used to make 3D mosaics in order to decorate their homes, the Greeks have manipulated perspectives to create impressive pantheons, and, at least, one paleolithic sculpture will look like two animals at the same time if you look closely.

Georg Rüschemeyer explores the science behind this, at least bizarre, effects of the optical illusion on the human brain in his latest book named “The New Book of Optical Illusions“. Much is lost in the communication process between the eyes and brain. In most cases, the two systems are a good team, but there are times when the eyes are transmitting confusing signals and the brain interprets them as it shouldn’t do.

The models are perhaps the most confusing ones. Your brain hates to decode the intricate patterns. For example, on the chessboard illusion below, white dots are creating spatial depth. The scientists have no explications, but it could be related model’s discontinuation. The brain wants to believe that the sheet has a uniform model, so it distorts the image in order to simplify it.

Are the eyes of this manga character different colors? Not at all, but the red filter makes the left eye appear blue, though it’s gray. This is similar to the controversy illusion that divided the Internet into two camps: those who saw it in white and gold and those who saw it in blue and gold.

Researchers at the University of Bristol found this illusion in the ’70s when watching a cafe walls. The gray lines between columns of the black and white squares appear to curve, but in reality, they are parallel. Your brain, overwhelmed by the contrast of black and white squares, perceives the lines as belonging to either the column from above or to the column below.

Another interesting optical illusion is the one of the violet flowers. Some people will see just a flower while others will see the profile of Napoleon Bonaparte, of his wife Marie Louise of Austria and their son. This type of image is often used to test certain mental abilities, including attention.