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Cognitive science, testing standards and the numbers behind them — written for a general reader, with every score carrying the scale it was measured on and the range around it.
A bad night does not lower intelligence. It reliably lowers the things a timed test happens to measure most closely — sustained attention, working memory and speed — while leaving vocabulary and general knowledge comparatively intact.
The sturdiest results are narrow and decades old. The 2025 studies that drew the headlines rest on self-reports and small preprints — and none of them measured intelligence at all.
Two people can perform identically on two different online tests and walk away with scores twenty points apart. The scale, the comparison group and the margin of error are what separate an assessment from a quiz.
Average scores climbed for decades, then flattened and in places slipped. None of it shows on a score report, because every test is reset so the average is 100 again — which is why a 1990 score is not a 2026 score.
Aptitude tests are among the better-studied hiring tools, and for decades the headline validity figures were quoted with more confidence than the corrections behind them deserved. A 2022 reanalysis pulled those numbers down.
The tables that circulate as national IQ figures come from one compilation built out of whatever studies existed, in whatever years, on whatever samples. Several of the numbers were estimated rather than measured.
On the scale most modern tests use, 120 sits around the 91st percentile. Change the scale and the same number moves. Add the measurement error every test carries and it stops being a point at all.
The numbers attached to famous names travel for decades without ever acquiring a test record, a date or a scale. Where the trail can be followed at all, it usually ends at a magazine paragraph.
Three rows, three columns, two things changing at once. The worked solution is below — and so is an honest account of what solving it does and does not tell you about yourself.
The correlation between them is one of the sturdier findings in cognitive psychology. How strong it is, and what it implies about training either one, is where the agreement stops.
Each desk covers a subject we can report on continuously and check against a source. Pick the one you care about — or read everything.
New peer-reviewed findings on how reasoning, memory and general ability actually work — reported with the sample size and the error bars.
Sleep, exercise, diet, illness, medication and environment — what each one measurably does to thinking, and by how much.
How machine reasoning is measured, where it beats people, where it still fails, and what any of it says about human intelligence.
Admissions exams, gifted programs, national score reports and school testing policy, explained without the spin from either side.
The cognitive and aptitude tests employers use, how they are scored, and what a score does and does not predict at work.
Chart-led pieces on how scores are distributed across countries, states, ages, jobs and education levels — always with the caveats attached.
What a specific number means on a specific scale, why every score needs a confidence range, and how the scales convert.
Viral IQ claims checked against the record: where the number came from, who repeated it, and what is actually documented.
A reasoning puzzle every day with the full working shown, plus honest coverage of what brain-training products can and cannot do.
Average scores climbed for decades, then flattened and in places slipped. None of it shows on a score report, because every test is reset so the average is 100 again — which is why a 1990 score is not a 2026 score.
The correlation between them is one of the sturdier findings in cognitive psychology. How strong it is, and what it implies about training either one, is where the agreement stops.
The sturdiest results are narrow and decades old. The 2025 studies that drew the headlines rest on self-reports and small preprints — and none of them measured intelligence at all.
IQ scales are defined by a human reference sample, and a language model is not in it. Placing a machine on that scale is not a hard measurement problem — it is a category error.
An IQ figure is meaningless without the scale it was measured on and the range around it. Every story here reports all three, or says plainly that the source did not.
Each story ends with the studies, datasets and documents it draws on, named and attributed, so you can go and read them yourself.
Spotted an error? Write to corrections@iqmetrics.org. Corrections are made on the story and noted at the bottom of it — never quietly.
Our IIF-certified assessment reports your score with its scale, percentile and confidence range — and a breakdown of the cognitive domains behind it.
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