Chromostereopsis: the most fascinating visual illusion

Chromostereopsis is a visual illusion in which we experience a sudden sensation of depth when the colors red and blue combine.. It is one of the most fascinating optimal phenomena. In fact, if it is current for something, it is because of the impact it has with the use of screens.

It has been discovered that with the use of mobile phones and computers, the illusion of depth is more intense. It is enough to check it by locking ourselves in a dark room. We open this image on an electronic device, increase the brightness and we can even perceive a false movement of the image.

The brain deceives us – it does it many times -, making us believe that a simple drawing suddenly acquires 3D characteristics. This chromatic aberration is the result of the differential refraction of light in relation to its wavelength. The interesting thing is that this characteristic has been known since ancient times.

So much so that many stained glass windows in the oldest cathedrals were already looking for the combination of certain colors to create that sensation, that unique – and supernatural – experience.

There are people who do not experience the phenomenon of chromostereopsis.

Chromostereopsis: what it is and why we experience it

If there is a fascinating book about the universe of color, its effects and nature, it is Zur Farbenlehre (color theory) by Johann Wolfgang von Goethe. It was written in 1810 and already at that time, the famous German poet, playwright and naturalist highlighted something: blue is a receding color and red is a protruding color. Furthermore, together they seem to “pierce” the organ of sight.

Something happens when we combine these two colors. And great artists have known this since ancient times. In fact, It is common to see how many stained glass windows and also paintings combine red and blue to generate depth and movement at the same time. Now, it was in 1860 when we had the first scientific explanation of the phenomenon of chromostereopsis.

Cornelius Donders, renowned Dutch ophthalmologist, suggested that When the retina captures the color red, it needs more time to accommodate and process it. If it appears next to the color blue, it will remain in the background, while the red tone will be placed in front.

Now, there are many more theories that explain this unique phenomenon, which, in reality, is present in more areas than we think.

The secret is in the fovea

The phenomenon of chromostereopsis would not be possible without the fovea. This is an area of ​​the retina where light rays are focused and we can process colors. Now, this part of the eye is located in the macula lutea and due to its position/orientation in both eyes, it does not capture the entire range of colors with the same accuracy.

Blue and red are at opposite ends of the light spectrum. This causes each wavelength to be focused differently, so that red always takes longer to process, and will always be ahead. The blue will be located behind, giving us an optical phenomenon of depth.

However, It is important to note that there are people who are “blind” to the phenomenon of chromostereopsis. The mechanisms of why this happens are unclear. However, and this fact is also curious, there are many people who do not capture a good part of the visual illusions; However, this does not condition their lives. In fact, they don’t even usually know that they have this singular anomaly.

The light spectrum of colors reaches different planes of the eye; However, not all of these planes coincide with the plane of the retina and the fovea, which is the part that processes them.

Chromostereopsis is part of the digital world and in nature

Studies, such as those carried out at the University of Latvia, reveal how the phenomenon of chromostereopsis is common in our digital media. It’s more, The light from cell phones and computers intensifies that perceptual experience much more. And what’s better, designers and big technology companies know this and try to take advantage of it.

Let’s think for a moment about all those media and applications that combine red and blue. The world of video games, for example, uses this optical effect constantly, as well as the settings in television programs. These two tones constantly accompany us in advertising.

On the other hand, it is fascinating to know that chromostereopsis is a resource that biology has integrated into the animal world. Butterflies have developed red circle patterns on their wings as a mechanism to defend themselves against predators.. How? That hue and those color schemes suggest the shape of an eye (an eye that stands out thanks to its hue). This keeps potential enemies away.

To conclude, we are faced with a type of chromatic aberration or optical phenomenon of great impact that is part of our daily lives, both natural, technological and even artistic. Those who can perceive it, enjoy it and become aware now of how many places they use these two tones together.

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