The dress illusion that had the population arguing whether the dress was blue and black or gold and white is nothing compared to this
There’s a trick that can make you see black and white as green and red for up to three and a half months. The trick is known as the McCollogh effect discovered by an American psychologist in Canada in 1965. By staring at the vertical and horizontal lines you’ll eventually start to see black and white as green and red.
WARNING: The effects can last for more than three months.
Are you ready?
Look at the test grid of black and white lines and confirm they do indeed look black and white. Then stare at ht esquare containing red and black stripes and the other one with green and black stripes for up to three minutes. 
And now, how to go blind!
Below you see a rotating array of blue crosses and 3 yellow dots. Now fixate on the centre (watch the flashing green spot). Note that the yellow spots disappear once in a while: singly, in pairs or all three simultaneously. In reality, the 3 yellow spots are continuously present, honest!
