If you move the rows, the lines appear to be sloping. We call this an optical illusion. This illusion was first discovered on the tiled wall of a café in Bristol, England.
When do you experience an optical illusion? It happens when our brain gets confused by the information from our eyes.
Optical illusion: flickering grid
How many black dots do you count? Spoiler alert: There are no black dots at all.
Optical illusion: the Penrose Triangle
An impossible 3D figure and yet you have to look twice before you realise it.
