It might sound strange, but it’s perfectly possible to be more intelligent than average without knowing it.

Not everyone has a good idea of how smart they are.

And for lots of reasons, such as low self-esteem, people may underrate their own intelligence.

I grew up in a very working-class environment, and I had lots of friends who were very smart but didn’t really think they were.

They came from backgrounds that didn’t prioritize intelligence or academic achievement, so they were more likely to be the class clown instead of studying in school.

Eventually, getting bad grades helped to convince them that they weren’t very smart, even when they clearly were.

There are lots of other signs that can tell you that someone isn’t confident in their own intelligence.

Keep an eye out for these behaviors, in others or in yourself, that can tell you that someone is unaware of how smart they really are.

1) They downplay their achievements

Modesty is by no means a bad quality to have.

But it can become a problem when someone goes beyond mere modesty and starts downplaying their own achievements.

Even if they have actually achieved a lot, they will act as if it’s no big deal.

They might have a great job, a wonderful family life, or have a history of doing amazing things.

But when asked about them, they will act as if it’s not a big deal, it was easy, or they simply got lucky.

This is especially true when it comes to intellectual achievements.

They may have won prizes for their work or achieved a high level of education, but they won’t accept praise for that.

Instead, they will act as if those things are not as impressive as they really are.

That’s because these people are uncomfortable with being praised.

Because they don’t think of themselves as being especially intelligent, they feel awkward when other people say that they are.

Even if there’s lots of evidence to prove their intellectual abilities, they will downplay it.

2) They don’t take credit

Along with downplaying their achievements, people who lack confidence in their intelligence often have a hard time taking credit for anything.

And it happens for exactly the same reasons.

This can happen in lots of different situations.

At work, they might refuse to take the credit for a big success, instead pointing to other team members and saying that really, it was all them.

In their personal life, they will deflect any compliments they receive about their spouse, their kids, or any other aspect of their life.

Tell them they have a good marriage, and they will give all the credit to their spouse.

Tell them they have great kids, and they will say they got lucky.

“A little modesty is a fine thing, but some of us have these self-deprecating reactions constantly,” writes philosophy professor Katherine Hawley. “When this reaction forms a distressing, recurring pattern of thought, it embodies a type of imposter syndrome.”

People who don’t have faith in their intelligence often suffer from imposter syndrome.

This means that no matter what they achieve in life, they will always feel like they are somehow faking it.

As if they got to where they are by sheer luck, and at any minute, they could lose it all.

As Hawley points out, people who suffer from imposter syndrome place too much trust in their own low opinion of themselves and not enough trust in the opinions of others.

This makes it very hard for them to accept a compliment or take credit.

3) They use self-deprecating humor

Just like modesty, there’s nothing wrong with self-deprecating humor by itself.

In many ways, self-deprecating humor is safe, because you are the target of your own jokes, so you can be funny without risking offending anyone.

But sometimes, self-deprecating humor can be a tool an intelligent person uses to hide a genuine lack of confidence.

“In multiple studies, self-deprecating humor is associated with lower self-esteem,” writes psychiatrist Grant Hillary Brenner. “Self-deprecating humor is associated with decreased forgiveness, further compounding self-esteem by making it harder to let go of perceived failures.”

It can be funny when someone makes fun of themselves, and when done sparingly, can be a sign that someone doesn’t take themselves too seriously.

But underneath the laughter, there may be a more serious reason why someone constantly makes themselves the butt of the joke.

4) They avoid participation

Lacking faith in their own intelligence, these people will often avoid participation wherever possible.

You’ll see this in the workplace during meetings, when people stay silent and try to fly below the radar, afraid of getting called on to give an opinion.

That’s because their fragile sense of their own intelligence is easily damaged by saying the wrong thing at the wrong time.

It seems easier just to keep quiet and not risk anything.

And because they don’t think they are particularly intelligent, they often feel they don’t have anything to add to a workplace discussion.

But it also happens outside the workplace, too.

You may be discussing something with your friends and notice one of them never gives an opinion.

Alternatively, they might change the subject when a conversation gets too deep, worried they won’t be able to keep up.

5) They are perfectionists

It might sound strange for people who lack faith in their own abilities.

But people who mistrust their own intelligence are often perfectionists.

They feel like they have to succeed at everything they do, even if it is new to them.

And often, they don’t react well when they get something wrong, because it confirms their low opinion of themselves and their intelligence.

Plus, in some ways, perfectionism is a way to avoid trying something difficult.

By insisting on waiting for the perfect time or demanding some impossible perfect result, people let themselves off the hook so they can stay in their comfort zone.

6) They are reluctant to try new things

The tendency toward perfectionism shows someone who is afraid to try new things.

After all, when you lack confidence in your abilities, you also lack the confidence to stretch yourself.

Because you don’t have any faith in your intelligence, you tend to assume that anything new you try will be a failure, and that it’s better to protect your ego by avoiding it.

Unfortunately, this tendency plays right into the most negative aspects of low self-esteem.

If you never try new things, you’ll never achieve your full potential.

And you’ll never realize how much you are capable of unless you are willing to sometimes fail.

7) They avoid challenges

Along with being reluctant to try new things, people who have no faith in their own intelligence often avoid challenges like the plague.

They tend to stick to their comfort zone, preferring what they know over something that may challenge them.

That way, they can avoid the negative feelings that come with failure.

For someone with low self-esteem, failing at something can be particularly damaging.

It confirms all the worst thoughts they’ve had about themselves and reinforces the cycle of anxiety and self-blame.

Of course, by avoiding challenges, people often ensure they will never enjoy great success, either.

That’s just one of the ways that low self-esteem can become self-reinforcing.

8) They agree quickly with others

People who lack faith in their own intelligence are often quick to agree with others.

That’s especially true of people they consider smarter than they are, or people in positions of authority, such as a boss or parent.

Disagreeing with each other sometimes is part of being human.

But it takes a certain level of self-belief to be open about that disagreement.

If you don’t believe in yourself, you’ll tend to assume that any disagreement you have with others must mean that you, not them, are wrong.

“People who score high in agreeableness are very down-to-earth and rarely claim to be better than others,” writes life coach Sherri Gordon. “They also are usually humble—sometimes to the point that they may have lower self-esteem.”

Even worse, this often means that they will agree with others when they are told that they are not particularly intelligent.

Like some of the people I went to school with, a low assessment from a teacher or other authority figure can stay with a person for life and convince them that they are not as capable as they truly are.

9) They seek reassurance

Finally, seeking reassurance from others is a clear sign that someone lacks the internal validation to recognize their own intelligence.

This may show itself by a person highlighting the things they’ve done to try and get the approval of others for their actions.

You may be even more direct, with a person literally drawing attention to their own intellect to try and get others to agree that they are smart.

Sometimes, this can even come off as arrogant.

But in reality, it’s the opposite.

Needing validation from other people is a sign that someone is unable to give themselves the necessary validation that comes from a healthy sense of self-esteem.

You may be smarter than you think

There are lots of reasons why someone ends up with a distorted impression of their intelligence.

After all, even the smartest of us do dumb things sometimes.

But if you notice these behaviors, either in yourself or others, it’s a good indication of someone who mistrusts their own intelligence.