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Count Master
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Subitizing & Numerosity Assessment
Dots flash for 0.5 seconds — how many were there?
10 rounds · 5–20 dots · accuracy % is your score
01 /How to Play
- A cluster of dots will flash on screen for exactly 0.5 seconds.
- Enter how many dots you saw using the keypad.
- Submit your answer before the next round begins.
- Complete 10 rounds — your accuracy percentage and average error are your scores.
- Dots range from 5 to 20 — estimates, not exact counts, are expected for larger numbers.
02 /The Science
Subitizing — from the Latin 'subitus' (sudden) — is the rapid, accurate, pre-attentive perception of small quantities (typically 1–4 items). For quantities above 4, the brain switches to estimation via the Approximate Number System (ANS), a phylogenetically ancient capacity shared with many non-human species. ANS acuity follows Weber's Law: the just-noticeable difference between two quantities is a constant ratio rather than a fixed number. Individual ANS acuity, measured by tasks like this, is a robust predictor of formal mathematical achievement from kindergarten through university.
Population Distribution
Based on population research data
03 /Pro Tips
- For 5 or fewer dots, do not count — let subitizing work instantly.
- For larger quantities, look for spatial patterns: rows, columns, clusters.
- Guess slightly higher than your estimate — humans systematically undercount in brief exposures.
- Do not try to count individually — the flash is too brief. Trust your gestalt impression.
- Practice improves ANS acuity measurably over weeks of regular training.
Note: This test is designed for entertainment and self-reflection purposes only. Results are based on self-report and are not a substitute for professional psychological evaluation, diagnosis, or treatment. If you have concerns about your mental health, please consult a qualified professional.