1. You have a messy desk
It’s hard to define intelligence. Psychologists have been trying to do this forever. According to Cornell professor Robert J. Sternberg, PhD, intelligence is the ability “to learn from experience, adapt to new situations, understand and handle abstract concepts, and use knowledge to manipulate one’s environment.” Skills like perception, learning, memory, reasoning, and problem-solving facilitate these abilities. To that end, certain habits may be evidence you’ve got these skills. For example, you’d think someone who was intelligent would be organized and have everything in their work space arranged neatly—but that’s not the case.
In an experiment from the University of Minnesota, people in a messy setting came up with more creative ideas than those in a neat space. “Disorderly environments seem to inspire breaking free of tradition, which can produce fresh insights,” says study author Kathleen Vohs, PhD. “Orderly environments, in contrast, encourage convention and playing it safe.” Creativity is one of the traits that smart people tend to possess—and so conversely, it may actually lead to messiness, adds Jonathan Wai, PhD, a research scientist at the Duke University Talent Identification Program (TIP). “I’d guess that it’s not messiness that helps creativity, but creativity which may create messiness,” he says. “Such people tend to get lost in thought focusing on a problem or issue, and cleanliness becomes of less importance than focusing on the problem at hand.”
2. You stay up late
A study from the London School of Economics and Political Science found that people who tend to go to bed later have higher IQs. The study authors believe the root of why this is lies in our evolution—because nighttime was a more dangerous place, our ancestors who ventured into it instead of going to sleep needed to be more intelligent. Also, staying awake into the night was a new idea that was attractive to curious minds. Today, our varying circadian rhythms still may reflect this. “Perhaps [some smart people] stay up later because their internal clocks are simply different,” Dr. Wai says. “Or, perhaps they stay up later because they tend to be introverted, and like being up late at night without distractions to think and solve problems.” But if you are a night owl, remember to still get your seven to nine hours of sleep.
3.You swear
It’s commonly thought that swearing is a reflection of low education and intelligence—the theory that when people can’t think of the right adjective, they resort to slang, including curses. But a study by renowned expert in cursing Timothy Jay, PhD, and colleagues found that people who could come up with more curse words had a larger vocabulary in general. “Taboo or ‘swear word’ fluency is positively correlated with overall verbal fluency,” Dr. Jay told Medical Daily. “The more words you generated in one category meant the more words you generated in another category, orally and verbally.” Linguistic ability is one of the traits of people with higher intelligence possess, according to Dr. Wai, so it shouldn’t be surprising that smart people know more curses—even if they don’t use them all the time. “It’s part of your emotional intelligence to know how and when to use these words,” Dr. Jay says.
4.You like cold showers
You may have heard of the trend of taking cold showers or swimming in cold water to give your body an energizing jolt. Although there isn’t a ton of scientific info on this yet, the authors of one study from Finland, where winter swimming is common, note “adaptation to cold water was associated with a significant decrease in tension and fatigue, and an improvement in mood and memory.” These are all things that can boost brain function and productivity. In addition, stepping out of your comfort zone and getting up the courage to turn the knob down might inspire you for the rest of your day, according to a New York Times article on cold showers. So if you’ve joined the Polar Bear Club, your habit may be giving your brain a burst of energy every day.
5.The sound of chewing annoys you
Have you ever been really aggravated when dining with a loud chewer? Or wished the person next to you on the bus would stop smacking their gum? Well, it might just mean you’re smart. A study from Northwestern University found that people who tested high in creative cognition tended to have an inability to filter out irrelevant sensory information—they have “leaky sensory gating.” This means you’re taking it all in, sometimes to a fault. “Leaky sensory gating may help people integrate ideas that are outside of focus of attention, leading to creativity in the real world,” the study authors wrote. Dr. Wai surmises that this might connect to the same reason smarties tend to stay up late—they like to work without distraction. Interestingly, other studies have shown that chewing gum yourself improves intellectual performance.
6.You doodle
Another habit of smart people is doodling—so if you enjoy this pastime, it may mean you’re intelligent, too. According to Sunni Brown, author of The Doodle Revolution, it’s a thinking tool that can affect the processing of information and problem-solving. This notion is backed up by scientific research—a study from the U.K. found that people were able to recall 29 per cent more information if they were doodling. Scribbling mindlessly has a benefit for memory, and also gives the brain a visual way to express concepts and emotions. Dr. Wai has a theory as to why: “Perhaps it’s not the actual act of doodling, but the act of taking a break of any kind that matters,” he says. “For example, the idea that your mind works unconsciously in the background even when you aren’t overtly focusing on a problem.”
7.You criticize yourself
We tend to think that intelligent people are confident—why wouldn’t they be, when they’re so smart? But research suggests that might not be the case. In a landmark 1999 study from Cornell University, scientists found that incompetent people couldn’t recognize their own incompetence, which led to inflated self-assessments. This has become known as the Dunning-Kruger effect. “For poor performers to recognize their ineptitude would require them to possess the very expertise they lack,” study author David Dunning, PhD, recently wrote in the Pacific Standard. “To know how skilled or unskilled you are at using the rules of grammar, for instance, you must have a good working knowledge of those rules, an impossibility among the incompetent. Poor performers,” he adds, “fail to see the flaws in their thinking or the answers they lack.” The study also found that highly competent people tended to underestimate their abilities. Smarties can recognize when they don’t know something—in fact, they know just how much more knowledge is out there. Instead of being overconfident, they tend to be self-critical.
8.You daydream
Although scientists have previously thought mind-wandering negatively affected the brain’s performance, new research suggests that may not be the case. A study from the University of California found that when given a demanding task, participants who took a break for undemanding tasks fared better at the original assignment. The researchers theorize that giving the brain an “incubation period,” by allowing it to wander during a mindless task, boosts problem-solving and creativity. Like doodling, this is “related to that working on a problem in the back of your mind even when you aren’t directly thinking about it,” Dr. Wai says. “Some stories of scientific discovery have mentioned the importance of stepping away from the problem, getting a change of scenery, and how that can help your mind encounter different ways of viewing a problem and potentially enhance creativity.” So if daydreaming is one of your habits, you may have higher creative and problem-solving skills.
9.You talk to yourself
You may think that mumbling to yourself makes you seem crazy, but in reality, it might be a sign of higher thinking, memory, and perception skills. In a study from the University of Wisconsin and the University of Pennsylvania, researchers asked participants to remember and find objects. They were better able to recall the list of items to look for if they had said the names of the objects out loud. “Language is not just a system of communication, but I’m arguing that it can augment perception, augment thinking,” study author Gary Lupyan, PhD, told Live Science. By vocalizing the names of familiar objects, “you’re activating visual properties in the brain to help you find them