How do you know someone is very smart? Here are 15 'subtle signs' people notice.

There is a big difference in how highly intelligent people communicate versus those with smaller IQs. A Redditor named Occyz wanted to know how people tell the difference by asking them to share the “subtle” signs that someone is very intelligent.

The question was a big hit on the forum, receiving over 3,700 responses.

A big takeaway is people think highly intelligent people are mentally flexible. They are always interested in learning more about a topic, open to changing their minds when they learn new information and acutely aware of what they don’t know.

In fact, according to the psychological principle known as the Dunning-Krueger effect, there is a big confidence chasm between highly intelligent people and those who are not. Low-IQ people often overestimate what they know about topics they need to familiarize themselves with. Conversely, people with high IQs underestimate their knowledge of subjects in which they are well-versed.

Here are 15 “subtle” signs that someone is highly intelligent.

1. They admit their mistakes

"When someone can admit a mistake and they know they don’t know everything."

2. Great problem-solvers

"They're very good at problem-solving. Even if it's something they have no experience with they always approach the problem from the right angle."

3. They appreciate nuance

"'I can hold two opposing ideas in my head at the same time.' Anyone who is willing to do that is intriguing to me. Especially with polarizing issues. They might actually be interesting to talk to."

4. They say 'I don't know'

"I like to call it being smart enough to know how stupid you are."

"100% this. I have a good friend who is a teaching professor at Cambridge. He is acutely aware of how ‘little’ he knows about areas outside his specialization."

5. They have self-doubt

"They struggle with imposter syndrome. Dumb people always think they’re [great]."

"It can happen but I’ve met plenty who don’t really doubt themselves. Instead, they take not knowing or not having any experience as an opportunity, just like people go down interesting internet rabbit holes. Really smart people can view mistakes as opportunities for growth and inexperience as an opportunity to gather new experiences."

The great American poet Charles Bukowski once wrote, “The problem with the world is that the intelligent people are full of doubts and the stupid ones are full of confidence,” and according to science, he’s correct.

“Ignorance is associated with exaggerated confidence in one’s abilities, whereas experts are unduly tentative about their performance,” Stephan Lewandowsky Chair of Cognitive Psychology, University of Bristol, writes for the World Economic Forum. “This basic finding has been replicated numerous times in many different circumstances. There is very little doubt about its status as a fundamental aspect of human behavior.”

6. They ask questions

"They are ok with being perceived as 'stupid' by asking questions — if we hold back in fear, we'll never truly learn. Plus, it's a good way to show others it's ok to question things if you don't understand — better off if we're on the same page instead of hoping things work out without being informed."

7. They love a challenge

"They feel challenged rather than threatened by new things, problems, ideas..."

"'I don't know' is the beginning of a puzzle, not the conclusion."

8. They know their audience

"They can adapt their communication style — vocabulary, tone, content, etc — to fit the situation and people they’re talking to, and it seems completely natural."

"It's a bit past code-switching, though code-switching is a part of it. Being able to explain complex thoughts in simpler terms based on audience demonstrates your understanding. If the only people who can understand you are fellow people with the same educational exposure as you, you just have knowledge, not intelligence."

9. They can simplify big ideas

"I consider someone intelligent if they're able to explain something incredibly complicated in simpler and more readily understood terms."

"Fantastic teachers can make learning nearly effortless."

10. They listen to people they disagree with

"Someone who can understand someone’s opposing view without having to agree with it or get angry over it."

11. They're humble

"They don't continually need to tell people how intelligent they are."

"At a certain point, they realize they are smarter at certain things than other people, but they understand the importance of being humble."

12. They take a moment

"They pause to think about a novel question instead of instantly blurting out an answer. Sometimes people think it means they've been 'stumped' and claim victory. No, they're thinking, analyzing, and formulating a reply."

This idea is backed up by science. A study published by IFL Science found that people who score high on intelligence tests answer easy questions quickly. However, they spend more time on questions complex questions than their less intelligent peers. They have the intelligence to wait until their entire brain has grappled with a problem before answering.

"In more challenging tasks, you have to store previous progress in working memory while you explore other solution paths and then integrate these into each other,” said lead author Professor Michael Schirner. “This gathering of evidence for a particular solution may sometimes take longer, but it also leads to better results.”

13. They're well-spoken

"I usually find that creativity, humor, and verbal acuity are good signs of intelligence. I generally see lack of empathy, low openness, and seeing the world in absolutes as signs of low intelligence."

14. Dry sense of humor

"Pulling it off requires an observant, quick wit with a nonchalant delivery that almost downplays its own cleverness. Like it means their immediate passing thoughts are often profound enough to be very funny without any real effort."

15. They are great storytellers

"They craft narratives for themselves and for others that are compelling, that make the world make sense, that invigorate and install a goal, a mission."

This article originally appeared last year.