'Purple Is A Delulu': It’s Not A Real Colour But An Illusion—Here’s What Scientists Say

Scientists reveal that purple isn't a real colour in the light spectrum but a visual illusion created by your brain. Discover how this beloved hue is actually a clever trick of perception.

In a groundbreaking revelation that turns centuries of colour theory on its head, scientists are challenging the very existence of purple as a “real” colour. According to recent research, what we perceive as purple isn’t a true hue at all—but rather a clever trick of the brain.

“Purple, then, is not the product of a direct stimulus but a neural illusion, a trick of perception that fills in a missing piece in our mental colour wheel.”

Unlike other colours found in rainbows or emitted by specific wavelengths of light, purple has no corresponding wavelength. It's not part of the linear electromagnetic spectrum in the way that red, blue, or green are. So where does it come from?

How the Brain Fakes Purple

To understand purple's phantom nature, you need to know how we see colour. Our eyes rely on three types of photoreceptor cells called cones—S-cones (short wavelengths, like blue), M-cones (medium, like green), and L-cones (long, like red). When light hits the retina, these cones send electrical signals to the brain, where colour is interpreted.

Here’s the catch: red and blue light sit on opposite ends of the visible spectrum. There is no single wavelength that represents both at once. Yet, when both reach your eyes simultaneously, your brain doesn’t reject the conflicting signals—it creates something entirely new.

“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.”

The Rainbow’s Dirty Little Secret

“You might be today years old when you realize there is no purple in the rainbow. There is no P in ROYGBIV.”

That acronym—Red, Orange, Yellow, Green, Blue, Indigo, Violet—represents the true spectral colours. Violet, unlike purple, does have its own wavelength and lives on the spectrum’s shorter end. It’s even the reason we get sunburned, thanks to its cousin, ultraviolet.

“But wait, what about violet? Well, despite what you may have come to believe, violet is not purple.”

Colour, Perception, and Illusion

Purple’s illusion arises from how our brain interprets input from cones that aren’t supposed to fire together. Unlike colours like orange or teal, which lie between primary wavelengths and are perceived through a straightforward blend of cone signals, purple is unique.

“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.”

The Neuroscience of Colour

The visible spectrum makes up just 0.0035% of the full electromagnetic spectrum. We can’t see UV or infrared light because their wavelengths fall outside the 350–750 nm range our cones respond to. Yet within that sliver, our brains can interpret over a million colour combinations—thanks to the overlapping sensitivities of our cone cells.

But when red and blue light combine, that overlap disappears. There is no physical "in-between." The brain does a workaround—manufacturing purple to fill the visual void.

“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.”

A Colour of Magic

Despite its ghostly origins, purple has long held deep cultural meaning—royalty, mysticism, and luxury. That symbolism might be even more fitting now.

“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.”