Now that the bin-fire of 2020 is in our rearview mirror, social media is returning to real conversations that really matter. Like how many colors an object has. Again.
Earlier this month, a classic optical illusion was posted on Twitter with the question “How many colors do you see?” The poster saw three.
How many colors can you see ???? see me 3 pic.twitter.com/IgEHtyzebZ
– jade⁷🍓 (slow ♡) (@ 0UTR0EG0) February 4, 2021
Others answered with numbers such as high as 17. And tens of thousands of comments followed in a heated debate about what the ‘real’ must be.
We don’t have a strong idea here at ScienceAlert on how many specific bands are in the image (it’s 11, right?). But we can offer some insights into what ‘s likely to happen.
Although it is difficult to say with certainty, the work seems to have been the result of an influence first described about a century and a half ago by the Austrian physicist Ernst Mach, the only a scientist who lent his name to the unit comparing the speed of an object with the speed of sound.
It was only in this situation that Mach’s interest in distance, and more in vision, had nothing to do with it. While working as a professor of mathematics and physics at the University of Graz in the 1860s, he developed a keen interest in optics and acoustics.
In 1865 he became interested in a picture similar to the one we are all currently considering – colors resembling slightly different shapes become easily recognizable when rubbed, but harder to tell. from each other when separated.
Mach’s understanding was that something strange was going on inside the eyeball, especially inside the photosensitive material that makes up the retina. These shady stripes were later named Mach Bands in his honor.
Surprisingly, his ideas were very appealing. Research using technology better than Mach ever hoped to come in has proven that the mechanics behind this strange trick are a retinal eye called a late blight.
Here ‘s the 101: your retina is a bit like the screen at the cinema, capturing projected light through the pupil. This screen is covered with receptors, some of which move more strongly under brighter light and send a guarantee of signals to the brain.
If we think of two cells sending two very similar signals to the brain, we are probably just assuming that they are of the same shadow. Our brain is fond of snapping, and in a busy world there is no time for splitting hair.
But nature has developed a clever trick to help our brain recognize patterns more easily among similar shapes. Once an individual light-sensitive cell sends a signal, it prompts its close neighbors to shine.
This competition makes little difference among groups of cells all shouting and shining so loud together.
But when a quieter group of cells, reacting to a darker shade, sits directly next to tall cells, this blocking effect on cells directly on the border causes them to respond in a unique way. , effectively increasing the contrast between the reflections.
(ScienceAlert)
The diagram above may help to understand what is happening. Brighter light triggers receptors to stimulate its corresponding cell cloud more intensely. At the same time, every light-sensitive cell damages the nerves of its neighbors.
The result is nerves on the border between different showers sending signals that add to the difference, providing a clear boundary signal to build your brain.
This capability plays a part in a number of optical scenarios, including a ‘scintillating grid’ of dots that you can never focus on.
While a late ban explains why our eyes can tell similar shadows better when they are side by side, it does not fully explain why some of us can’t tell the difference between colors of very different brightness, as in this picture.
Inhibitory effects in our cells may be something we all experience to some degree, but it is very likely that this is the only factor that tells our brain how to interpret an image. Many of them will be unique to our eyes, brains, computer screens and the surrounding environments.
Surrounding light sources, differences in the brightness of our screens and monitors, and even the cellular shape of our retina all change. Our brains will set a level of correction in their own specific way according to their experience and the hard wire.
With so many variables, it is expected that we will not all agree on exactly where one shade of pink stops and the next begins.
This is all fun and games on Twitter, but by understanding more about how our retinas increase differences in the shapes that fall on them we can help find ways to improve our vision.
Now, keep in mind, we’re not at all saying we’re experts in optics here at ScienceAlert. This is all a consideration from one science writer who happens to have a deep love of the psychology of illusions.
But we do know that, in addition to questions about how many colors (or, more accurately, eyes, tones, textures, and shades) a rectangle contains, there is an interesting biology going on that many can tell us about what we have in common.