Instant Comparison
A clinical measure of numerical magnitude processing speed. Two math expressions appear side by side — identify the larger value as fast as your brain allows.
Numerical Magnitude Processing
Click the LARGER value · 3 seconds per round
Gets harder as you score · wrong or timeout = game over
01 /How to Play
- Two math expressions will appear side-by-side (e.g., 7 + 3 vs 12 - 4).
- Click the side with the HIGHER numerical value as fast as possible.
- Both speed and accuracy are measured — wrong answers end the test.
- Expressions get progressively harder as your streak grows.
- Your score is the number of correct comparisons before your first mistake.
02 /The Science
Numerical magnitude comparison activates the intraparietal sulcus (IPS), a region specialized for representing numerical quantity on a mental number line. This approximate number system (ANS) is present in infants and non-human primates, suggesting it is a core evolutionary cognitive capacity. Response time follows Weber's Law: close numerical values take longer to discriminate than distant ones. Individual differences in ANS acuity are significant predictors of formal mathematical achievement across the lifespan.
03 /Pro Tips
- Estimate, don't calculate — your ANS is faster than deliberate arithmetic for obvious contrasts.
- For close values, prioritize scanning the dominant operands quickly.
- Subtraction slows most people — practice spotting negative contributions at a glance.
- If both sides look similar, trust your gut — ANS intuition is often faster than conscious calculation.
- Fixate center to catch both expressions in peripheral vision simultaneously.