Visual Perception: Forbidden Colors

2024 Author: Seth Attwood | [email protected]. Last modified: 2023-12-16 15:55

Just as it is impossible for a person to bend and extend an arm at the same time (don't even try), you will never see reddish green and yellowish blue colors. No, we are not talking about brown and green, which are obtained by mixing these color pairs. It is the reddish green and yellowish blue colors. There are no such in the palette, do not look.

Physiology is built on the principle of opposition - antagonist muscles act opposite to each other. The neural mechanisms of color opposites work by a similar principle.

Red-green and yellow-blue are a kind of colors invisible to the human eye, which are also called "forbidden". Their light frequencies in the human eye automatically cancel each other out.

According to Ewald Göring's opponent color theory, which was later developed by David Hubel and Thorsten Wiesel, information does not come to the brain about red, green and blue (Jung-Helmholtz color theory). The brain receives information about the difference in brightness: white and black, green and red, blue and yellow (while yellow is the sum of red and green). For their discovery, they received the Nobel Prize in 1981.

Retinal pigment epithelium of the human eye. The letter R denotes rods - one of two types of photoreceptors, peripheral processes of light-sensitive cells. The letter C denotes another type of photoreceptor - cones

According to the basic provisions of the science of visual perception, the mechanism of immunity of the fusion of opposing colors is directly related to the processes occurring in the three types of retinal cones and the visual cortex. She is responsible for processing visual information. Everything is clear here.

When we look at an object, the initial information is formed in the retinal photoreceptors (cones), which perceive light waves in three different ranges. Neurons add and subtract the incoming signals, and then transmit further information about the four primary colors - red, green, yellow and blue. At the same time, our visual system has only two channels for transmitting color data: “red-minus-green” and “yellow-minus-blue” channels.

While most colors are combined information from both data transmission channels, which our brains interpret in their own way, red light cancels green, and yellow “cancels” blue. This is why a person is unable to see reddish green and yellowish blue.

In 1983, the journal Science published an article by Hewitt Crane and Thomas Piantanida, scientists from the Stanford International Research Institute.

The material argued that invisible colors can still be seen. The researchers created images in which red and green and blue and yellow stripes were placed next to each other. The images were shown to dozens of volunteers using an eye tracker, a device developed by scientists that tracked eye movements and stabilized the position of color fields on the retina.

This ensured that light from each strip of color always hit the same photoreceptors, even despite nystagmus - involuntary vibrational eye movements of high frequency (up to several hundred per minute) that could affect the purity of the experiment.

Volunteers reported that they saw how gradually the borders between the stripes disappear, and the colors seem to flow into each other. Surprisingly, the images of Crane and Piantanida suppressed the fusion immunity mechanism of the opponent colors.

The research of scientists, with all the importance of the discovery, caused only surprise in the world of science. They talked to them like crazy, since their article did not fit into generally accepted ideas.

You may never see reddish green and yellowish blue in nature. They are also absent on the color wheel, whose sectors represent the determined colors, arranged in an order conditionally close to the location in the spectrum of visible light. Nevertheless, subsequent variations of the 1983 experiment confirmed that "forbidden" colors are not so forbidden, and at least in laboratory conditions they can be seen.