First it was the blue/black and white/gold dress that almost made a lot of people believe they were indeed mad [I for one thought I had lost it]. Now this photo of a bizarre optical illusion has surfaced online and is about to break the internet.

Here’s how it works: Stare at the white dot at the centre of this negative of a woman’s face. After about 15 seconds, glance at the white blank space to the right of the photo.

That really scary figure transforms into the beautiful full-colour face of a young brunette woman.

This optical illusion is known as a ‘negative afterimage’ and is caused by cells located in the eyes, called ganglion cells, which send messages to the brain by coding – or identifying – colours in pairs of primary colours.

If you really got it, what color of dress is she wearing on her sleeve?