Scientists manipulate human eye in lab experiment to get it to see brand-new color

Scientists have developed a groundbreaking technique that allows the human eye to perceive entirely new colors outside the natural range of human vision. Researchers used this method to enable five participants—including some of the scientists themselves—to see a never-before-seen color they named "olo." Described as a deeply saturated blue-green, olo surpassed the vividness of even laser light in the eyes of those who experienced it.

In a recent study published in Science Advances on April 18, the authors explain how the technique centers on precise control of the retina’s photoreceptors—light-sensitive cells known as rods and cones. Rods handle low-light vision, while cones, which come in three types (L, M, and S), allow us to see color by detecting different wavelengths of light corresponding to red, green, and blue. Normally, these cones respond to overlapping light ranges, making it difficult to stimulate just one type without affecting the others. The research team, led by James Fong, a Ph.D. candidate at the University of California, Berkeley, wondered what would happen if they could isolate the activation of M cones, which are most sensitive to green.

To do this, the team developed a retinal stimulation system called "Oz," inspired by the green-tinted glasses worn in the Wizard of Oz. The technique involves mapping the retina of each participant using detailed video imaging, which is then used to guide targeted laser stimulation. This precision allowed the team to selectively stimulate M cones, essentially creating a new pattern of retinal activity that the brain interprets as a novel color.

Oz works by bypassing the traditional limitations of cone overlap, opening the door to seeing new colors never before accessible to human vision. According to Fong, the resulting experience of seeing "olo" was so vivid that even intense laser light seemed dull by comparison.

The implications of this research extend far beyond just discovering new colors. The ability to control photoreceptors individually could significantly advance the study of visual processing and eye diseases. For example, researchers could replicate the effects of conditions like color blindness or macular degeneration in healthy eyes to better understand how they impact vision. Moreover, the technique might eventually be adapted to help color-blind individuals perceive colors they normally cannot see by simulating the presence of missing or damaged photoreceptors.

While promising, the Oz system does face some technical challenges. Currently, participants cannot look directly at the Oz display because the cones in the fovea—the central part of the retina responsible for sharp vision—are too small for precise laser targeting. As a result, subjects must use their peripheral vision to perceive olo. Improving the technique to work with the fovea would be a major breakthrough but remains a complex task.

Despite its current limitations, the Oz system represents a significant step forward in neuroscience and vision research. It not only enhances our understanding of how the eye and brain process color but also hints at a future where human vision could be programmable, customized, and expanded far beyond its natural limits.

By Nazrin Sadigova