👁️ Eye Tricks
How easily your eyes get fooled. About 1 minute.
Slide until the red line or circle looks the same size as the black one.
About 1 minute. 6 quick pictures. Everyone gets fooled a little, so just go with what looks right.
Why does this happen?
Your brain doesn't measure things like a ruler. It judges size by looking at what's around them, which is usually a helpful shortcut.
Fins pointing outwards make a line look longer, and fins pointing inwards make it look shorter. Scientists call this the Müller-Lyer illusion.
A circle ringed by big circles looks smaller, and one ringed by small circles looks bigger. This one is called the Ebbinghaus illusion.
Almost everyone is fooled a little, even when they know the trick. Being fooled just means your brain is using its normal shortcuts.
How it's measured
You see 6 pictures, taking turns between lines and circles. Use the slider to change the red one until it looks the same size as the black one.
After each one, the fins or rings fade away so you can see the real sizes, and how far off you were.
Your score is how far off you were on average, as a percentage of the black one's length or width. Lower means the tricks fooled you less.
Your results and history are saved in this browser. Each finished score is also sent to us anonymously (just the game, the score and whether you used a phone or a computer; no name, no account) so everyone can see how they compare. Just for fun: not a medical, IQ or hiring test.
More Brain Breaks
- ⚡ Reflex: how fast you react
- 🎨 Colour Clash: how well you override autopilot
- 🎯 Arrow Focus: how well you block out distractions
- 🔍 Odd One Out: how fast you scan a busy scene
- 🧠 Number Memory: how quickly you search your short-term memory
- 🔄 Twist It: your mind's eye for shapes
- 👀 Spot the Change: how quickly you notice a change