Seven common mistakes people make on online IQ tests

From skipping warm-up questions to taking the test late at night, these everyday mistakes can shave 10–15 points off your result. Here is how to avoid them.

Practical tips · 2026-05-20 · 7 min lesetid

By Brain Test Editorial · Last updated 20 May 2026

Online cognitive tests are designed to be quick and self-administered, which means a lot of avoidable mistakes end up baked into people's scores. Here are seven we see most often.

1. Taking the test exhausted

Cognitive performance drops sharply when you are sleep-deprived. A 2010 meta-analysis found that one night of poor sleep lowers reasoning performance by an effect roughly equivalent to one alcoholic drink. Take the test in the morning, well-rested, ideally before any caffeine crash.

2. Multi-tasking during the test

Notifications, music with lyrics, a TV in the background — they all eat into working memory. Close other tabs, silence your phone, and give the test 25 uninterrupted minutes.

3. Rushing the first few questions

Most people warm up over the first 3–5 questions. If you race through them to "save time", you may answer easy items wrong and lose anchor points that would have boosted the score.

4. Spending too long on a single question

The opposite mistake. If a question is genuinely hard, give it your best guess and move on. Time pressure is part of the design — spending three minutes on one item costs you three other items.

5. Forgetting that English is a second language

Verbal subtests are biased toward fluent speakers of the test language. If your strongest language is not the one the test is offered in, expect verbal scores to underestimate ability. Brain Test is available in 13 languages — pick the one you read fastest.

6. Treating one score as final

Your score will fluctuate ±5 points day to day, sometimes more. Take the test twice in a week and look at the average if you want a more stable estimate.

7. Comparing to clinical IQ scores

An online test is not standardised against a real reference population the way the WAIS or Stanford-Binet are. Treat the number as a casual indicator, not a diagnosis. If you want a clinical assessment, contact a licensed psychologist.

None of these tips will turn an average score into a genius score — but they can help your result reflect what you actually can do on a good day. Try the Brain Test after a good night's sleep and see for yourself.

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