Which of these ‘strange’ pictures is ‘normal’?
Well, you probably think that all of these pictures look strange to begin with!
But when you stare at the ‘strange’ picture, then at the black and white picture it changes into you should notice an after effect image that creates a correctly coloured ‘normal’ image for a few seconds.
Except for one ‘strange’ picture! Which one?
Stare at the strange picture for 30 seconds, then at the black and white picture to see an after effect image.
Then vote if the after effect image appeared in its ‘normal’ colours or if the after effect image appeared in even weirder colours.
When you see a ‘ghost’ image following a camera flash, it’s a little similar to the after effect images you see after staring at these ‘strange’ pictures.
Both are effects caused by overstimulating receptors or cones in your eyes’ retinas.
The ‘strange’ pictures are digitally altered so they’re inversely coloured. When you mix a colour with its inverse colour you get white.
We should have made the ‘strange’ stop sign picture greenish, so its after effect image would be its inverse colour red. Instead, we made the stop sign green, so its after effect image appears purple. It was our little trick!
Now, back to the other test pictures which we manipulated properly! How did they work?
When you stared at red patches in one of the ‘strange’ pictures, certain cones in your retina underwent chemical responses and sent signals to your brain which it interpreted as “I’m seeing red”.
But because you kept staring, the cones became overstimulated and less sensitive to the red.
Then, when your overstimulated receptors see white in the black and white picture, they sent a signal to the brain about white, minus the colour that overstimulated them in the first picture (such as red).
This is interpreted by your brain so it sees the inverse colour (such as green for the red over stimulation).
Your brain thinks it’s looking at those inverse colours until the receptors settle back down to normal and you see the second picture for what it really is—black and white.