You can throw a stone in any direction and hit someone who is over-confident and thinks they're smarter than they really are. But even more common are people who don't realize they're actually smarter than they think.

Is that you? Here are nine science-backed signs that you're not giving yourself enough IQ credit.

1. You're creative.

Dr. Katie Davis, a clinical neuropsychologist, told Business Insider that creativity is a definitive sign of intelligence because it requires thinking flexibly/outside the box and necessitates the ability to shift and change your patterns of thinking from one way to another.

I've worked with many ad agency creatives--they're some of the smartest people I've ever met. Their ability to take an insight and translate it into a message that illuminated my brand's benefits in a compelling, memorable way is a task few merely "book smart" people could do. I often walked away after a brilliant ad campaign presentation thinking, "Their brain just works differently." Creativity is its own brand of smart.

2. You're messy.

Kathleen Vohs from the University of Minnesota says the messier you are, the smarter you are. A study Vohs published in Psychological Science featured two groups asked to devise creative uses for Ping-Pong balls. One group worked in a messy, cluttered environment while the other worked in a tidy setting. The messy group brainstormed substantially more creative and interesting ideas.

So before berating yourself for your perpetually cluttered desk, give yourself a few IQ points instead.

3. You're curious.

If you love to learn, the more you'll learn and the smarter you'll get. Science backs this up. A study from Goldsmiths University of London found that "how people invest their time and effort in their intellect" (i.e. feeding their curiosity) plays a huge role in cognitive growth.

But it's not just learning more that makes you smarter, it's wanting to learn more, which is a trait common in intelligent people. A study in the Journal of Individual Differences showed a correlation between people who scored high on IQ tests as a child and adults that were more curious and open to new ideas.

Psychology research from Georgia Tech also showed that those with high curiosity are more tolerant of ambiguity, which requires a sophisticated thinking style.

4. You talk to yourself.

No, it's not a sign you're crazy--just the opposite. A study from psychologists Paloma Mari-Beffa and Alexander Kirkham of Bangor University showed that talking out loud to yourself improves self-control, an important form of intelligence. They gave study participants a set of tasks and accompanying written instructions, asking them to read the instructions silently or out loud. Measured concentration and performance from those who read out loud was far better.

Talking out loud nets control, which is why so many professional athletes talk to themselves out loud during games. Which brings us to the next sign.

5. You have high self-control.

Whether you exercise self-control by talking to yourself out loud or just by willing it, it's an overlooked sign of intelligence. A 2009 psychology study from Yale University gave participants IQ tests and offered them reward money they could receive immediately or later (for a higher amount). Those choosing to wait also had higher IQ scores, indicating that resisting making impulsive decisions and carefully weighing options correlates with intelligence.

6. You're good with being by yourself.

If you like your own company and aren't constantly in need of being around others, that's a sign of intelligence. A study published in the British Journal of Psychology showed a correlation between contentedness with being alone and intelligence. I use alone time to think, prioritize, and plan, which reinforces self-control (sign No. 5). 

7. You're funny.

A 2011 University of New Mexico psychology study found that professional comedians and people who wrote funnier cartoon captions scored higher on verbal intelligence. This adds up, as some of the smartest people I know have a razor-sharp wit and sense of humor.

8. You're open-minded.

A 2008 Yale University psychology study showed highly intelligent people tend to stay open-minded to others' points of view, not formulating their own until hearing multiple voices. This doesn't mean they're fickle, though, as the study also showed open-minded people are more likely to be confident about their opinion once formed and less likely to be manipulated.

9. You're not convinced you're particularly smart.

Psychologists discovered the Dunning-Kruger effect, which says that people who are less competent or bright consistently overestimate their mental abilities while intelligent people are far more aware of their limitations.

And knowing your limitations means you're more likely to surround yourself with people to offset your limitations. It also makes you hungrier to learn more, which makes you smarter (sign No. 3).  As Shakespeare said, "The fool doth think he is wise, but the wise man knows himself to be a fool."