How the test and scoring work
We would rather show you the limits than a number that only looks precise.
The tasks are original
Every task is generated from rules written for this site. None is copied from a published or protected test. Automated checks confirm that each task in the bank has exactly one answer that follows from what you can see.
How the score is calculated
Each correct answer counts the same; a blank counts as wrong; speed does not change the score. The estimate equals 70 + 60 × (correct answers ÷ all tasks), rounded. You can check this yourself on your result page.
Why the scale is provisional
We have not yet given the test to a representative group of people. So we do not know how people in general score, and 100 here means half of the tasks solved, not average ability. For the same reason we show no percentile, no statement about the population, and no claim of correlation with other tests.
What has not been tested
Difficulty levels are our design intent and have not been measured on people. Versions A, B and C have the same structure, but their equivalence has not been established. Nor have we measured reliability or validity.
Accessibility
The site works with a keyboard, and you can turn off the timer. Because the tasks are visual, they currently cannot be completed with a screen reader alone.
What would change this
A real norm study: thousands of consenting participants, described by age and country, and ideally a comparison with an established test run with an academic partner. If that happens, this page will state the sample and the method, and results will say so.