Strange things happen when you focus on the black dot and keep staring into the red spot.
Keep your eyes steady and focussed until you detect that something strange is happening to your vision.
Then, vote for the effect you experienced and see how you compared with other people.
For some people, the red spot fades away completely until they only see green, while others may see a yellow halo around the red spot.
Usually when your eyes make tiny, jittery saccades (up to five per second), receptors in your retina are constantly refreshed with new information.
But when you’re strongly staring at the red spot, your receptors don’t get refreshed as much as they usually do and they start to get fatigued.
Also, the red spot has a fuzzy edge instead of a black lined edge or border.
Because the edge is fuzzy instead of sharp, your eye can’t distinguish between the red and green areas as well as it normally can. If the dot had a distinct border, your receptors could be refreshed with information about the border as well as the colours.
In fact, your visual system seeks out borders or edges all the time. But because it can’t detect any borders, your brain ‘fills in’ the gaps and you start to ‘see’ things that aren’t there.