How good is YOUR colour perception? Deceptively difficult test tasks you with finding the boundary between two shades – so, how far can you get?

Can You Detect the Barest Hue Difference? A Challenging Color Perception Test Reveals Your Limits

A groundbreaking test challenges your understanding of color perception, pushing you to question even your most basic assumptions about hues. Designed by software engineer Keith Cirkel, the game is based on the concept of ‘Just Noticeable Difference’ (JND), which measures the smallest color change detectable by the human eye.

How the Test Works

The ‘What’s My JND?’ test presents two color blocks on your screen and asks you to identify the boundary between them. While the initial rounds are straightforward—showing distinct colors like grey and blue or brown and orange—the difficulty escalates rapidly. As the game progresses, the shades grow increasingly similar, demanding sharper visual focus to succeed.

Rough. But look, I once failed a colour vision test because the room had fluorescent lighting. Environment matters. Try again in a dark room with your brightness cranked. Or don’t. I’m not your mum.

The test typically spans about 40 rounds, with the average participant scoring 0.02. This figure reflects the precision of human color discrimination, yet it’s not the end of the journey. For those eager for more, a Hard Mode awaits, featuring nine squares—eight identical and one subtly different. The challenge here is to spot the anomaly, testing even greater attention to detail.

The Science Behind Color Perception

Color vision relies on the complex structures within the eye, such as cones and rods, which function as photoreceptors in the retina. Cones detect color, while rods excel in low-light conditions, enabling grey-scale vision. Humans and several other species possess three types of cones, each responsive to different light wavelengths. This triad allows us to perceive the entire visible spectrum, from red (around 700 nm) to blue (approximately 390 nm).

Some animals, like many birds, have an extra type of cone, a trait known as tetrachromacy. This mutation enables them to detect light in the ultraviolet range, expanding their visual capabilities beyond human perception. When light strikes these photoreceptors, they generate electrical signals that travel to the brain via the optic nerve. The brain processes these signals at the optic chiasm, where it compares the visual input from both eyes to create a cohesive image.

Genuinely remarkable. You sailed past the theoretical human limit like it owed you money. I’d accuse you of cheating but I don’t actually how you’d cheat at this.

Players often share their experiences on social media, highlighting both the test’s intrigue and its difficulty. One user noted, ‘This is great fun. How good is your colour perception? What are the finest shades you can distinguish? Apparently I’m a bit special.’ Another observed, ‘Some were just completely uniform to me. I had no idea. Had to keep tilting my screen all ways to try to spot a border but still ended up guessing.’ A colorblind participant quipped, ‘Not bad considering I’m colourblind.’