What a cognitive ability test measures, and what 20 questions cannot tell you

A clock shows 3:15. What is the angle between the hour and minute hands? The quick answer is zero, because the minute hand points at the 3. But by a quarter past, the hour hand has moved a quarter of the way towards the 4, so the correct answer is 7.5 degrees.

That question comes from our General Cognitive Ability test. Several of its questions reward checking the first answer that comes to mind before you click.

Four areas, five questions each

The test has 20 questions, each with four answers and only one correct. You have 20 minutes, and when the time runs out the test submits whatever you have answered so far. The questions fall into four areas of five:

• Verbal reasoning: odd one out, analogies such as "BOOK is to LIBRARY as PAINTING is to:", a grammar question and a proverb.
• Numerical reasoning: percentages, sequences and proportions, such as "If 3 workers complete a job in 12 days, how many days will 9 workers take?"
• Logical reasoning: syllogisms such as "Some cats are black. All black things absorb heat. Therefore:" and simple pattern rules.
• Spatial reasoning: shapes and objects described in words, such as the number of edges on a cube, or the clock question above.

Our spatial questions have no pictures. That makes them partly a test of whether you know some geometry, while picture-based tasks such as mental rotation measure your ability to picture objects more directly.

Where the four areas come from

In 1904 Charles Spearman noticed that people who did well on one kind of mental task tended to do well on others, and he called the shared factor general intelligence, or g. In the 1940s Raymond Cattell split general ability into fluid intelligence, solving problems you have not met before, and crystallized intelligence, the knowledge and skills you have built up. In 1993 John Carroll reanalysed a large body of earlier data and proposed a three-level model: g at the top, a set of broad abilities below it, and many narrow skills at the bottom.

Our test borrows that layout loosely. We wrote all 20 questions ourselves, inspired by this research, so the test has not been validated or normed. Your result shows how many questions you answered correctly in each area. It is not an IQ score, and it cannot place you against other people.

Knowledge or reasoning

Some questions lean on what you already know. Completing a proverb or choosing the grammatically correct sentence draws on crystallized knowledge and depends on the language you grew up with. Others need a short chain of reasoning. In the workers question, three times as many workers finish in a third of the time, so the answer is 4 days. The trap is to multiply because the numbers seem to invite it.

When you look at your result, check which kind of question you missed. Errors on knowledge questions say more about what you have read or learned than about how you think. Errors on reasoning questions usually come from answering too fast.

How to read your score

Each area has only five questions, so a single answer is a fifth of that area. One slip under time pressure can make an area look weak, so treat one low area as something to look at again, not as a finding. A short timed test also says nothing about creativity, practical judgement or how you learn over time.

For a longer test, try our IQ test, which adds working memory and has a 25-minute limit. The spatial reasoning test covers mental rotation, and the post on what an online IQ test measures explains what tests like these can and cannot tell you.