Level 1
Tries ●●●
Best –
How to play
Goal
Find the one square whose colour is a little different from all the others. Keep going as the difference gets smaller.
How it works
- All the squares are almost the same shade, but one is slightly lighter or darker. Tap it.
- Each correct tap takes you up a level: the grid grows and the difference shrinks.
- You have three tries. A wrong tap costs a try, and the right square is shown.
- There is no clock. Look as long as you like.
Tips
- Soften your gaze and look at the whole grid at once instead of one square at a time.
- Squint a little: small differences in shade show up more clearly.
- Turn up your screen brightness. Very dim screens hide small differences.
The history of Odd One Out
Seeing small differences in colour is a real skill that doctors and designers test. The Japanese ophthalmologist Shinobu Ishihara published his colour-vision plates in 1917, and in 1943 the American Dean Farnsworth devised the 100 Hue Test, in which people arrange coloured caps by shade. Spot-the-difference puzzles like this one are a gentle, everyday cousin of those tests.