Methodology
Every challenge uses a fixed, versioned set of items and a simple scoring rule. Here is exactly how each one works.
Scoring rules (version 1)
- Reasoning and spatial: one point per correct item. Wrong or skipped items score zero. There is no negative marking and no conversion to an IQ number.
- Reaction time: the median of valid responses (10 on Entry, up to 20 on Regular and Hard). Pressing before the cue is a false start. Times below 100 ms or above 2000 ms are excluded. If too few valid responses are collected, no score is given.
- Memory: one point for each sequence repeated in exactly the right order.
- Attention: hits, misses, false alarms and correct rejections, reported as balanced accuracy, with median response time on correct targets.
- Spot the difference: each changed region counts once. Wrong taps are recorded but not penalised.
- Colour, hearing and visual challenges: raw correct counts only. No diagnostic labels, hearing levels or acuity fractions.
- Multitasking: symbol task accuracy and memory task accuracy reported separately, plus joint accuracy.
Levels and versions
Every challenge has three levels. Entry is the original starter set and is unchanged. Regular and Hard each use a fixed set of 20 new items, built from the same rules with more steps, closer choices or less time. Each level keeps its own score, history and score guide, and every saved result records its level and item set version, so results are only ever compared within the same level and version.
- Reaction time Hard is a choice reaction task (respond on the matching side). It measures something different from simple reaction time and is never compared with Entry or Regular.
- Hearing Hard uses quieter tones. A harder item never plays a louder sound.
- Colour, vision and hearing levels change only the challenge; none of them becomes a screening or diagnostic test.
Premium breakdowns
Premium shows the same session in more detail, such as accuracy by item type, response times trial by trial and which items you missed. It never changes how the basic score is calculated.
Score guide
The Stats tab places your latest result on a general score guide for that kind of test. For reaction time the bands follow typical browser-measured simple reaction times. For the other tests they are set by the share of items you got right. The guide helps you read your number. It is not a percentile, a population norm or a diagnosis.
Content status
All items are original material made by ChowChow Labs. Difficulty labels describe how the items are built (more rules, longer sequences, closer choices), not measured population difficulty, and may be adjusted as results come in.
Limits
Browser timing depends on your screen, input device and system. Colours and sound depend on your display and headphones. Nonverbal items reduce reading demands but do not remove cultural, educational, motor or device effects.
Changelog
- 24 October 2026: pages and challenges translated into French, Simplified Chinese, Traditional Chinese and Japanese (best effort; English prevails).
- 23 October 2026: added Regular and Hard levels (item set versions v2-regular and v2-hard) to all ten challenges. Entry items (v1-starter) unchanged. Results now record their level and version. The About the test pages were merged into each test page.
- 20 October 2026: launch with Entry items (v1-starter) for all ten challenges.
Made and maintained by ChowChow Labs. Last substantive review: 24 October 2026.