After carrying out a series of experiments with the aid of a prism, Isaac Newton (1642-1726) showed that it is possible to break down white light into seven colors. In 1704 he published his conclusions in ‘Opticks’, a work that he sent forever into the corner of oblivion the belief that light was colorless.
In our civilization we have names to designate the basic colors: blue, red, yellow… but this does not happen in all cultures. There are some that only have two categories, white and black; in those in which there is a third it is always red and when two more categories are included they are always green and yellow.
In our retina we have cells -the cones- that absorb and encode the different wavelengths coming from visual stimuli and that they send to the visual cortex by means of electrical signals through the optic nerve.
The colors that we perceive are really a construction of our brain, involving both structures of the visual cortex and the hippocampus and the limbic system, areas related to emotions, therefore the perception of a color goes far beyond a simple process. neural.
In this way, color is the brain representation of certain wavelengths that reach our retina and are properly interpreted by our brain.
Now let’s imagine for a moment one of those times when we woke up in the middle of the night and opened our eyes. Everything is dark, we are unable to see what is around us since we do not have a reference point that allows the photosensitive cells of the retina to send signals to the brain.
Now, is that color exactly the same as the one our eyes distinguish in broad daylight and which we have named ‘black’?
What we really see is ‘intrinsic gray’
From the outset, black is not a primary, secondary or tertiary color, on the other hand, the color that the human eye perceives in complete darkness in German it is called ‘Eigengrau’ and it is not black. Although we do not have an equivalent color, we could translate it as ‘own grey’ or ‘intrinsic grey’.
It is, therefore, a color that is lighter than black and that is produced as a result of the spontaneous activation of certain photosensitive cells in our eyes. Somehow it is a perception of ‘something’ that does not really correspond to reality and that could be considered a physiological hallucinatory phenomenon.
Eigengrau is not the only biological hallucination that we have, when we go from wakefulness to sleep we have hypnagogic hallucinations, while hypnocampic hallucinations occur when we wake up.
A very unstable color
The Eigengrau is, then, an optical illusion, a product of a confused state of our visual system. Although we do not have a specific word to refer to this color, we do have its own hexadecimal code, #16161d, while for black we use #000000.
This color is produced because our rods have a photosensitive protein made up of opsin and vitamin A, which is extremely unstable, which means that it can lose its integrity spontaneously, causing the eye to send signals to the brain, somehow making it ‘believe’ that a photon of light has arrived, when it has not really happened. It is an unstable color that can vary from person to person and also over time.
Although for many it is an absolute unknown, the Eigengrau color came of age a long time ago, since it was coined in the mid-nineteenth century by the Teutonic psychologist, Gustav Theodor Fechner. This scientist, who also introduced the notion of the median in statistics, defended that the Eigengrau color was the last derivative of a ‘visual noise’.