What are the signs of high intelligence?

The signs with the best evidence describe ability: learning new things quickly, solving unfamiliar problems, a large vocabulary and broad knowledge, holding several pieces of information in mind at once, and a lasting appetite for ideas. Popular habits such as staying up late or keeping a messy desk are not good signs. None of these replaces a properly administered test.

What are the signs of a genius?

“Genius” is not a scientific category with a cut-off. In everyday use it means exceptional achievement in a field, which depends on ability, years of practice, opportunity and persistence together. A very high IQ score is not the same thing: many people with high scores never produce exceptional work, and some exceptional achievers have unremarkable scores.

Can you tell how intelligent someone is by talking to them?

Roughly, yes. In one study of 600 people, judgements of intelligence made from short video clips predicted measured intelligence well; how people read short sentences aloud was a particularly strong single cue. Another study found that attentive, responsive conversation and eye contact while speaking helped observers judge accurately. But these are group-level findings; any one impression can be badly wrong.

Are night owls more intelligent?

Not in any way that would let you judge a person by their bedtime. Treat staying up late, messy desks, swearing or talking to yourself as habits, not as signs of intelligence. The messy-desk claim, for example, comes from experiments that measured creativity on a single task, not intelligence.

Do intelligent people know they are intelligent?

Only loosely. A meta-analysis of 41 studies found that people’s estimates of their own ability correlate about .33 with their measured ability. Estimates were more accurate for numerical ability and when people compared themselves with a clearly defined group.

What IQ counts as high intelligence?

On the usual scale, where the average is 100 and the standard deviation is 15, a score of 130 is two standard deviations above the mean and is reached by about 1 in 44 people. Scores from 120 are often described as superior. Only a properly administered test gives a reliable number, and every score has a margin of error.

Signs of High IQ and Intelligence: What the Evidence Says

The most reliable signs of high intelligence describe what a person can do: learn quickly, reason through unfamiliar problems, use a wide vocabulary, hold several things in mind at once and keep seeking out ideas. The viral “quirky habits” — night owls, messy desks, swearing — have little evidence behind them. And no sign is a measurement: even people’s judgements of their own ability match their tested ability only loosely.

Signs of ability versus signs of personality

Most lists of “signs of a high IQ” mix two kinds of thing. Some items describe ability itself — how fast someone learns or how well they reason. Others describe habits, tastes or personality traits that are supposed to travel with intelligence. The first kind is close to what an IQ test measures. The second kind is, at best, a weak correlation that holds on average across thousands of people and tells you little about any one person.

Signs with real evidence behind them

Learning quickly and solving new problems. This is fluid reasoning, the ability at the heart of tests such as Raven’s Progressive Matrices: working out a rule you have never seen before, with little explanation.
A large vocabulary and broad knowledge. Knowledge builds up over years and reflects both ability and exposure. It is the “crystallized” half of the fluid-versus-crystallized distinction.
Holding several things in mind at once. Following a long argument, doing mental arithmetic or juggling the parts of a plan all lean on working memory, which is closely linked to reasoning ability.
A lasting appetite for ideas. A 2013 meta-analysis of 112 studies and more than 60,000 participants looked at “investment” traits — personality traits that shape how much time and effort people put into thinking and learning. They were linked to markers of adult intellect — knowledge, grades and crystallized intelligence — with an average correlation of about .30, ranging from 0 to .58 depending on the trait and the measure.
Quick, inventive humour. In a study of 270 young adults, the ability to come up with funny ideas on the spot was strongly related to general intelligence. This is about producing humour, not about enjoying jokes.

Even these are tendencies, not tests. Someone can be curious and well-read without an unusually high score, and a highly able person can be shy, slow-speaking or uninterested in books.

The “quirky habits” that do not hold up

Search results for this topic are full of habits said to reveal a high IQ: staying up late, keeping a messy desk, swearing, talking to yourself, sarcasm. Treat them with caution. A single study is not a sign, and some of these studies did not measure intelligence at all.

The messy-desk claim is a good example. In a 2013 set of experiments, people who worked in a deliberately disordered room were more creative than people in a tidy room; people in the tidy room chose healthier snacks and gave more money to charity. The study manipulated the room, not the person, and measured creativity and choices — not intelligence. It says nothing about whether people with messy desks are smarter.

Can you spot intelligence in other people?

Better than chance, it turns out. In one study, 600 people were filmed in 15 short episodes and also took intelligence tests. Observers’ judgements of intelligence from the clips predicted the test scores well, and one of the strongest single cues was how a person read short sentences aloud. Another study found that observers judged strangers’ intelligence more accurately when the strangers were responsive to their conversation partner and looked at them while speaking.

These are averages across many judges and many people. Accent, confidence, shyness, nerves and simple familiarity all colour a first impression, so any single judgement of a single person can be well off.

Can you tell if you are smart?

Only roughly. A meta-analysis combined 154 results from 41 studies comparing people’s estimates of their own ability with their test scores. The overall correlation was .33. People were more accurate about numerical ability than about general ability, and more accurate when asked to compare themselves with a clearly defined group. In other words, plenty of people who think they are unusually bright are not, and plenty who doubt themselves score well — a pattern explored in our guide to the Dunning–Kruger effect.

Where intelligence shows up over a lifetime

The clearest “signs” appear only across large groups and many years. A meta-analysis of 16 studies with more than 1.1 million participants found that each standard-deviation advantage in cognitive test scores in youth (about 15 IQ points) was associated with a 24% lower risk of death over follow-ups of 17 to 69 years. Adjusting for adult socioeconomic status or education weakened the link considerably, so part of it seems to run through the jobs, income and education that test scores help predict. None of this lets you read one person’s intelligence from their life story.

What counts as a high IQ in numbers

On the usual scale the average is 100 and the standard deviation is 15. A score of 130 sits two standard deviations above the mean and is reached by about 1 in 44 people; 145 by about 1 in 741. Our guides to what counts as a good IQ and the IQ scale explain the bands. If you are thinking about a child rather than an adult, see our guide to IQ testing for children, and for the combination of high ability with a learning difficulty, twice-exceptional.

Trust and scope notes

This page summarises published research for general information. Most findings described here are correlations across groups, not rules for individuals. The IQ Revealed test is an online reasoning test of 40 original items for adults aged 18 and over; it is not a clinical assessment, and our guide to how IQ tests work explains what an online test can and cannot tell you.

IQ Revealed is not affiliated with, endorsed by or connected to the journals, universities, researchers or studies named on this page, or with the publisher of Raven’s Progressive Matrices. Names are used only to identify the research being described.

Signs of High Intelligence: What the Research Actually Supports