Is Purple Doesn’t Exist? Scientists Say It’s Just a Brain Illusion—Here’s Why

In an innovative discovery that defied centuries of colour theory, scientists revealed that purple isn’t a real colour at all—but a clever illusion created by the brain. According to new research, what we see as purple is not produced by a specific wavelength of light like other colours. Instead, it is “a trick of perception that fills in a missing piece in our mental colour wheel.”

Unlike red, green, or blue—which all correspond to specific points on the visible light spectrum—purple does not exist as a standalone wavelength. 

It doesn’t appear in the rainbow and isn’t a direct result of any singular light frequency.

“Purple, then, is not the product of a direct stimulus but a neural illusion,” scientists explained.

The Science Behind the Illusion

To understand how the brain “fakes” purple, researchers broke down the process of colour perception. Human eyes rely on three types of cone cells in the retina that detect different wavelengths of light like S-cones respond to short wavelengths (blue), M-cones to medium wavelengths (green), and L-cones to long wavelengths (red).

When light enters the eye, these cones send electrical signals to the brain, which then interprets the combination as a specific colour. However, since red and blue are on opposite ends of the spectrum, there’s no real in-between wavelength that blends the two.

“According to the researchers, the mind essentially ‘bends’ the linear colour spectrum into a circle, imaginatively linking red and blue to fill the gap with a phantom hue.”

This mental bending leads to the creation of purple—a colour that doesn’t actually exist in nature as light, but is instead a product of neurological interpretation.

No Purple in the Rainbow

This also explains a surprising fact: there is no purple in the rainbow. The visible spectrum, often memorized by the acronym ROYGBIV—Red, Orange, Yellow, Green, Blue, Indigo , Violet—does not include purple. That’s because violet, the final colour in the rainbow, has its own distinct wavelength, unlike purple.

“You might be today years old when you realize there is no purple in the rainbow. There is no P in ROYGBIV.”
“But wait, what about violet? Well, despite what you may have come to believe, violet is not purple.”

Violet sits at the extreme end of the visible spectrum and is physically measurable, while purple is not.

Also Read: Katy Perry to Fly Into Space with Blue Origin on April 14: How and When to Watch the Flight LIVE

Why Purple Is Unique

What makes purple different from secondary colours like orange or cyan is that it doesn’t lie between red and blue on the spectrum. Instead, the brain fills the visual gap when it receives conflicting signals from red and blue cones.

“When you see both of these wavelengths in the same place, your eyes and brain don’t know what to do with them, so they compensate, and the clashing wavelengths register as the color we call purple. It doesn’t actually exist.”

Unlike orange, which results from overlapping red and yellow wavelengths, or teal, formed between green and blue, purple is simply a workaround by the brain.

“The problem with purple is that it isn’t supposed to be possible to create a color from wavelengths on opposite ends of the spectrum.”

The Neuroscience of Seeing Colour

Scientists also explained that humans perceive colour in only a tiny fraction of the electromagnetic spectrum—just 0.0035%. The rest, including ultraviolet and infrared light, lies beyond our perception.

Within the 350–750 nanometre range, our cone cells can interpret millions of colour variations. But purple is an exception—there’s no physical basis for it, only brain-generated perception.

A Royal Illusion

Even though it doesn’t truly exist, purple has held deep symbolic value for centuries, often linked to royalty, mysticism, and luxury.

“Despite the fact that it is technically a figment—more like pigment—of our imaginations, purple has earned a rich reputation… Maybe the most appropriate association is that last one.”

So while purple may not be real in the scientific sense, its influence on culture, art, and identity remains very real—a reminder of how powerful our brains are in shaping the world we see.