Autumn and Winter Check-in Challenge
What color do you see when you close your eyes?
Here's a hint – it's not black.
What we're actually seeing is a unique color that has its own specific name – the characteristic color.
Technically, this German word translates to "inner gray", but now it is more commonly said to be "brain gray".
Although the history of the term is uncertain, it first appeared in the 19th century. Gust** Fechner, a pioneer of experimental psychology, is most credited with coining the term.
Fischner has spent much of his career studying the relationship between sensations and the stimuli that produce them.
In the case of Eigenglu, he noticed that even when people were in complete darkness – whether in a pitch-black room or with their eyes closed – they could still see signs of gray.
So where did this new color come from?
From our own eyes.
The eye is an amazing organ, and it's very complex, but when we transmit what we see from the outside world to the brain, it relies on two types of cells – rods and cones.
At its most basic, the cones see the colors, and the rods focus on light and contrast – basically black and white.
In low light, the brain relies more on rod-shaped cells than on cone cells, which continue to capture as many photons as possible (light particles in nature, but like everything in physics, more).
And, when we close our eyes, these rod cells don't seem to close. They continue to send signals to the brain, which creates the illusion of seeing the faintest light – hence seeing gray, not pitch black.
Or Intrinsic Gru.
Of course, that's not the only thing you can see with your eyes closed.
After rubbing your eyes, you may notice flashes of light, swirls, or spots of light. These are called phosgene, and like the eigengram, they are caused by the eye sending signals to the brain to produce light hallucinations – in this case, due to pressure on the eyeball.
Speaking of what it feels like to really not exist, earlier this year, scientists discovered that humans can "hear" silence, settling an apparently centuries-old debate.
So now you know.