The brain is pretty well known for its ability to play tricks on people, and optical illusions are perhaps the most obvious way in which it might do so. The internet has been filled with optical illusions since it was first created, but rarely are any able to achieve viral popularity like this one. The image is a simple plate of strawberries, and while the whole image appears strangely off-color, the strawberries still appear ripe and red. The trick is that the image doesn’t contain any red pixels. Every color in the picture is either green or grey.
The image was created by Akiyoshi Kitaoka, a Japanese psychology professor at Ritsumeikan University. He has studied the art of optical illusion for quite some time, and he has an entire website filled with other images he has created. None, however, are as widely discussed as the plate of ‘red’ strawberries. The idea behind the image of the strawberries is the same color concept that caused a huge national debate over the color of ‘The Dress’ in either black/blue or gold/white. It’s known as color constancy, and the basis of the principle is that the human mind attempts to stabilize color balance when illumination changes. This allows humans to see the same spectrum regardless of light intensity, but it can be used to fool the mind into thinking artificial images are something they really aren’t.
Basically what this means is that you see the strawberries as red because that is what color they are supposed to be, and since the color spectrum of the image allowed your brain to superimpose potential colors onto the scene, they appear red. Your brain is constantly picking up visual stimulation in two primary formats. The first is the standard wavelengths of light reflecting off objects, and the second is the light that illuminates the surroundings. By using photography manipulation, this photo has been made to appear darker by removing the red colored pixels, but the spectrum is still same as it would be if they were in normal lighting. The brain then automatically translates the color of the strawberries into something that appears as red as possible in context with the rest of the image.
Interestingly, when the image is artificially brightened from this point, the strawberries appear even brighter along the red hue, despite there still being no red pixels. Some people see the image and instantly think they are being pranked with the idea that there is no red in the photo. To prove that is the case, one Twitter user created color profiles for each color in the photo, including the strawberries, and compared those colors against a white background. Each was very clearly a different shade of grey when taken out of the context of the image. In other words, it’s not just the hue of the grey, but the fact your brain is seeing a strawberry that it expects to be bright red, that makes this phenomenon work.
Even when overlaying a rectangle of the color with the original image to visually prove the colors are all grey, your mind will still force you to see some residual red. It is merely a part of the biological function of the system that detects sensory information for the brain to process. It’s interesting to think about how often something is experienced that doesn’t relate to the outside reality. Perhaps your brain is only telling you that something is happening. Who’s to say what reality truly consists of when everyone only knows a portion of the truth via electrical impulses interpreted by the brain?