How good is YOUR colour perception? Deceptively difficult test tasks you with finding the boundary between two shades – so, how far can you get?
How precise is your color vision? A challenging test reveals the limits of human perception
A novel interactive challenge is designed to probe the intricacies of color perception, pushing participants to question their assumptions about visual accuracy. The test, titled ‘What’s My JND?’, presents a seemingly straightforward task that quickly becomes complex as it progresses.
The core mechanism involves two color blocks displayed on screen, with the goal being to locate the dividing line between them. While the initial rounds appear manageable, the difficulty escalates rapidly, as the hues converge to the point of near indistinguishability.
‘You see two colors. Click on the line between them. That’s it. It starts easy. It does not stay easy,’ the game’s instructions clarify.
Players are required to complete 40 rounds, with the average performance benchmarking at 0.02. This figure represents the smallest detectable color shift, known as the Just Noticeable Difference, which the game aims to identify through its progressive design.
Keith Cirkel, a software engineer, developed the game to explore the precision thresholds of color recognition on digital displays. The test can be accessed via a dedicated platform, where users initiate the challenge by tapping the ‘Let’s go’ button.
As the test advances, the color pairs become increasingly similar, demanding heightened attention. Following each attempt, the system provides immediate feedback on whether the boundary was accurately detected or if the guess was significantly off.
Test variations and player experiences
For those seeking an added challenge, Cirkel has introduced a ‘Hard Mode’ variant. In this version, participants are shown nine squares—eight identical in hue and one distinct. The task remains the same: identify the odd color out.
‘Rough. But look, I once failed a color 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.’
Players often share their results on social media, with some expressing surprise at their performance. One user remarked, ‘This is great fun. How good is your color perception? What are the finest shades you can distinguish? Apparently I’m a bit special,’ while another joked, ‘Not bad considering I’m colourblind.’
Some describe the test as perplexing, noting, ‘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.’
The science of color vision
Color perception in humans and other species relies on specialized photoreceptor cells in the eye. These include cones, which detect color, and rods, which are sensitive to low-light conditions, enabling grayscale vision.
Humans possess three types of cones, each responsive to different light wavelengths. This trio allows for a broad range of color discrimination across the visible spectrum—approximately 390 to 700 nanometers—encompassing hues from red to blue.
Animals such as birds exhibit a mutation called tetrachromacy, where four types of cones enable the detection of ultraviolet light. This adaptation expands their ability to perceive light wavelengths beyond human capability.
When light interacts with these photoreceptors, it triggers electrical signals that travel through the optic nerve to the brain. These signals are processed at the optic chiasm, where the brain compares visual inputs from both eyes to create a cohesive perception.
