It may sound like a seemingly easy question, being asked to name whether the colour in front of you is blue or green.
But a tricky new quiz throws any confidence you had in solving the 50/50 option out of the window.
In the baffling new illusion, opticians have placed five strikingly similar shades of green and blue next to each other.
They say if you can’t spot the subtle difference, it does not mean you have a colour vision deficiency, which affects almost three million Britons.
Instead, opticians claim the difference is only how the brain perceives the colour.
It may sound like a seemingly easy question, being asked to name whether the colour in front of you is blue or green. But a tricky new quiz throws any confidence you had in solving the 50/50 option out of the window
Take the test for yourself below
Optical Express drafted the quiz, which tricked hundreds of people in a survey, as part of National Eye Health Week.
One of the colours the 1,000 people quizzed struggled to spot included Tiffany Blue, trademarked by the jewellery retailer.
Around two fifths of respondents polled assumed the shade was blue – even those it is closer to green on the RGB spectrum (113, 208, 197).
The quiz of five colours was prompted by another illusion from Optical Express that asked patients to identify whether one square was green or blue.
Two thirds of people quizzed were adamant this shade was green, while the remaining third disagreed – stating it was blue.
However, when asked to name the same colour adjacent to two distinctly blue images, the rate that thought it was green jumped.
Opticians said the colour has the values 0, 122 and 116 on the RGB colour spectrum – meaning the shade is only slightly more green than blue.
Stephen Hannan, clinical services director at Optical Express, said: ‘Isn’t the brain an extraordinary thing?
‘Every single person is unique and as a result, our brains process information differently.
‘Depending on how you interpret colours, one person might see it one way, while the very next person who looks at it might see it differently.’
Mr Hannan explained light enters the eye, passes through the natural lens and hits the retina, which is the light sensitive tissue at the back of the eye.
The light is converted to an electrical signal which travels along the optic nerve to the visual cortex in the brain.
The brain makes its own unique interpretation of this electrical signal, meaning people often see different colours to others.
Mr Hannan added: ‘It is not surprising that many respondents changed their mind when seeing the colour in contrast to the two blue shades.
‘We perceive an object’s colour based on a comparison to its surrounding shades, not on the actual colour itself.’