Now you see it: Web sensation of the dress that changes colour

Now you see it: The two-tone dress that has sparked a global debate on Twitter over what colour it is.

The figure-hugging frock has divided opinion on Twitter and Facebook, with some people insisting it is black and blue and others claiming to see white and gold.

A picture of the £50 knee-length dress is reported to have first been posted online by Caitlin McNeill, 21, from Scotland.

Although Birmingham-based Roman Originals describe the dress as being royal blue and black, friends of Miss McNeill noticed several different colours in the garment.

Ms McNeill told the BBC that she posted the picture on a photo-sharing site after her friend’s mother wore the dress at a wedding.

She said: “A week beforehand the bride had been sent by her mother a picture of the dress she was going to wear and when the bride showed her fiance, they disagreed about what colour it was.

“She was like, ‘It’s white and gold’ and he said, ‘It’s blue and black’. So they posted it on Facebook to try and see what their friends were saying but that caused carnage on Facebook.”

A spokesman for Roman Originals said the in-demand outfit briefly sold out, adding: “It’s black and blue but we’re definitely looking into a white and gold version.”

One explanation for the debate is that the dress causes an optical illusion, stemming from how the human brain processes colours.