How good is YOUR colour perception? Deceptively difficult test tasks you with finding the boundary between two shades – so, how far can you get?
A novel challenge has emerged that forces participants to reconsider their understanding of color recognition. The ‘What’s My JND?’ test requires identifying the dividing line between two hues, a task that seems simple but rapidly escalates in complexity.
The Mechanics of the Test
Players are presented with two color blocks on their screen and must click the line separating them. While the initial rounds are straightforward, the difficulty intensifies as the shades become increasingly similar. As the game progresses, the gap between the colors narrows until the player’s ability to detect the slightest difference is tested.
Each round challenges the participant to pinpoint the boundary. After every attempt, they receive feedback on whether their choice was accurate or significantly off. The test typically spans around 40 iterations, with an average score of 0.02, indicating the threshold of perceptible color variation.
The Science Behind Color Perception
Humans and many other species rely on intricate eye structures to perceive color. The pupil regulates light intake, functioning like a camera lens. Photoreceptors—cones and rods—reside in the retina, with cones enabling color detection and rods aiding in low-light vision, which facilitates a grey-scale perception.
Humans possess three types of cones that respond to short, medium, and long wavelengths of light. This combination allows for a broad spectrum of visible colors, spanning from red to blue. Some animals, including numerous bird species, have a mutation known as tetrachromacy, which grants them four cones and the ability to discern ultraviolet light.
When light interacts with these photoreceptors, it triggers electrical signals that travel to the brain via the optic nerve. These signals converge at the optic chiasm, where the brain compares the two visual inputs, creating a unified perception of color.
User Engagement and Feedback
The game has gained traction online, with players sharing their results on social media. One user remarked,
‘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 added,
‘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.’
Players with color vision deficiencies have also shared their experiences. A participant quipped,
‘Not bad considering I’m colourblind.’
For those seeking a greater challenge, the test offers a Hard Mode. In this version, nine squares appear—eight identical and one distinct. The goal is to locate the odd square, a task that demands heightened focus and precision.
Keith Cirkel, the software engineer behind the game, designed it to explore the limits of color perception. The test’s instructions highlight its progressive nature:
‘You see two colours. Click on the line between them. That’s it. It starts easy. It does not stay easy.’
The challenge underscores how environmental factors, such as fluorescent lighting, can affect color recognition. A message encourages players to retry in a darker setting, suggesting,
‘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.’
