Is the color you see the same as the one I see? It’s a question that has been around for centuries, sparking debates among philosophers and neuroscientists alike. While the subjective quality of perception, such as the “redness” of red, for example, remains elusive, new research suggests that the way our brains process color is far more universal than once thought.
A study published in the Journal of Neuroscience on September 8 has shown that color perception can be decoded across different people, not just within the same individual. The findings suggest that human brains share a consistent neural “code” for colors, shedding light on one of the most fundamental aspects of visual experience.
Researchers Andreas Bartels and Michael Bannert from the University of Tübingen in Germany examined how color is represented in the brain and whether those representations are consistent across individuals. “Now we know that when you see red or green or whatever colour, that it activates your brain very similarly to my brain,” says Bartels. “Even at a very low level, things are represented similarly across different brains, and that is a fundamentally new discovery.”
To test this, the researchers used functional magnetic resonance imaging (fMRI) to record the brain activity of 15 participants as they viewed a series of colors. The scans revealed distinct, finely tuned patterns in the visual cortex, the part of the brain responsible for processing visual information. Some cells showed stronger responses to specific hues, such as red or green, and these preferences were arranged in consistent ways across participants.
The next step involved machine learning. Bartels and Bannert trained a computer model, known as a linear classifier, on the fMRI data from one group of participants. They then asked it to predict which colors were being observed by a second group, based only on their brain activity. The model succeeded in many cases, decoding not only which hue was being viewed but also its brightness.
Previous studies had shown that a person’s brain activity could be used to predict which color they were seeing, but only if the training data came from the same individual. This study is the first to demonstrate that the brain’s representation of color is consistent enough across people to allow accurate decoding between different brains.
“This shows that there are commonalities in the way different brains encode colour,” says Bannert. “And these have something to do with the way that our brains represent visual space.”
The discovery also challenges existing theories about how color is processed in the brain. Jenny Bosten, a color-vision scientist at the University of Sussex in the UK, describes the finding that some neurons appear biased toward particular colors as “a new finding that I was surprised by, and doesn’t really fit with our theory of how those areas of visual cortex process colour.” Still, she acknowledges its importance: “If it stands the test of time—which there’s no reason why it shouldn’t—it might change how we view colour-coding in the cortex.”
Despite the revelation, the study does not fully resolve the philosophical question of whether colors look the same to different people. Bannert is cautious, stating, “We can’t say that one person’s red looks the same as another person’s red. But to see that some sensory aspects of a subjective experience are conserved across people’s brains is new.”
While our private experiences of color may still differ in ways science cannot measure, the underlying neural architecture appears to be universal. The research suggests that humans may share a common biological language for processing color, one that transcends individual perception.
By bridging the gap between subjective experience and shared brain function, this study brings us a step closer to answering that age-old question: when we look at the world in all its hues, are we seeing the same thing?
