Girl's hair changes colour when she walks into different rooms

It's that blue and black (or white and gold) dress all over again.

A US man has filmed his girlfriend walking between her kitchen and the adjoining bathroom, but in the space of a few metres, her hair colour appears to change several times.

Initially starting a light purple, it turns pink when Sabrina Abu-Obeid steps into the bathroom.

In a darker patch of the kitchen on the way back the hair appears to be blue.

"What colour do you think my hair is? Blue, purple, pink, violet, or all of the above?" she wrote in the video posted online this week.

"My boyfriend saw my hair change colours from pink to purple / blue and wanted to show me what he was seeing so he decided to shoot a quick video for me."

Her boyfriend DJ Monopoli's awestruck reaction is pretty spot on.

Like the blue and black (or white and gold) dress that went viral earlier in the year, the hair colour change all appears to be a trick of the light.

But despite this being an optical illusion, there doesn't seem to be much room for debate as to what colour Ms Abu-Obeid's hair is. It just depends on what room she's in.