Akiyoshi Kitaoka is a professor of psychology at Ritsumeikan University in Tokyo. He specializes in the field of perception and optical illusions. So he sometimes shares his experiences on his Twitter account.
The photo above has no red pixels, yet the strawberries on this pie appear to be red.
This optical illusion is created using a phenomenon known as “color constancy.” It’s basically your brain’s way of correcting what you see based on light or lighting conditions.
When you look around, the light entering your eye is made up of different wavelengths that come from both the pigments of the objects around you and the light that illuminates them.
For Bevil Conway, expert in visual perception,
If you imagine yourself walking outside under a big blue sky, that blue, in a way, contaminates everything you see with its color. If you take a red apple outside under a big blue sky, there are more blue wavelengths entering your eye. If you take that same apple inside under fluorescent or incandescent lighting, the pigments in the apple are exactly the same, but because the spectral content of the light source is different, the spectrum of colors reflected by the object and reaching your eye is different.
So, since these lighting influences on colors are not really useful for our perception (and are even disruptive), our brain has evolved to correct colors. This allows us to see colors the same way, regardless of the lighting.
This image has been cleverly manipulated so that the objects you see reflect something achromatic or grayscale, but the light source that your brain interprets has a blue component to it. Your brain says, "The light source I'm looking at these strawberries under has blue in it, so I'm going to automatically remove that on every pixel." And when you take gray pixels and remove the blue bias, it gives you red.
Furthermore, the interpretation of this illusion is made possible by the fact that we recognize strawberries as such and strawberries are strongly associated with the color red. Our brain therefore makes the connection very easily.
Remember, color constancy was the explanation for the divergent views on the colors on the famous dress that had animated the web. Since the light source was not clear, people's brains corrected the colors differently.
This picture has NO red pixels. Great demo of color constancy (ht Akiyoshi Kitaoka) pic.twitter.com/pZHvbB6QHE
— Matt Lieberman (@social_brains) February 27, 2017
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Article updated on January 6, 2025 by Byothe
