I once overheard two coworkers debating whether street smarts were better than book smarts.
One guy was adamant that knowing random trivia made him a genius, while the other insisted that true intelligence is about how we adapt in everyday life.
Their conversation got me thinking: Intelligence isn’t just IQ scores and fancy degrees.
It also shows up in our small, daily habits—and some of those habits can actually reveal a surprising lack of mental agility.
Below, I’ll share eight habits that psychology points to as indicators of a lower level of intelligence.
Recognizing them can be the first step to avoiding these pitfalls and improving ourselves in the process.
1. Closed-mindedness on repeat
I’ve met plenty of folks who cling tightly to their opinions and refuse to entertain new viewpoints.
They won’t even consider the possibility that someone else might have a piece of the puzzle they’re missing.
This lines up with what an interesting study found: open-mindedness is linked to intelligence and divergent thinking.
In other words, people who can’t adapt their beliefs when presented with new facts have a kind of tunnel vision that holds them back from learning and growing.
In my workshops, I’ve seen closed-mindedness derail great ideas. I once had a client who believed that social media was a “waste of time,” despite her business clearly needing online visibility.
No matter how much proof I provided, she stuck to her guns. Eventually, she realized she’d missed huge opportunities by rejecting something she hadn’t truly explored.
It was a classic example of closed-mindedness limiting both her potential and her success.
2. Inflating self-importance
I’m all for confidence. In fact, I coach people to stand tall and embrace who they are.
But there’s a big difference between healthy self-esteem and inflated self-importance.
Overestimating one’s abilities is a phenomenon psychologists link to something called the Dunning-Kruger effect—basically, the less skilled someone is, the more they tend to think they’re an expert.
Being humble enough to accept criticism can actually signal a higher form of intelligence, because it means you’re willing to learn.
Those who brush off all feedback as “other people just don’t get it” risk stagnating in their ignorance.
3. Leaning heavily on stereotypes
We all make snap judgments at times—our brains are wired for quick decisions, after all.
But stereotyping entire groups of people based on minimal information is a sure sign of mental laziness.
Instead of doing the work to understand individuals, a person with this habit slaps a label on them and moves on.
I used to see this a lot when I worked in a global marketing agency. Some would say, “Tech people are all introverts,” or “Millennials are always glued to their phones.”
These blanket statements fail to reflect reality, and even worse, they shut down curiosity.
Adam Grant once noted that true intelligence involves the capacity to rethink and unlearn.
Stereotyping keeps us stuck in oversimplified worldviews, which blocks our ability to adapt, empathize, and innovate.
4. Rejecting novelty without thought
I’ve noticed that some folks, faced with anything novel—a new project, a fresh cuisine, a different route to work—immediately say, “Nope, I’m good.”
They don’t even try it.
This quick-dismiss approach can be linked to a lower capacity for critical thinking. Instead of evaluating the pros and cons, they default to rejection.
A few years ago, I recommended a coworker check out a new industry conference that had just launched.
He insisted it was a “waste of time” without exploring the speaker lineup or content.
That same event turned out to be a goldmine for networking and introduced me to a few mentors who’ve changed my professional trajectory.
Refusing novelty outright can be one of the greatest blockers to growth—and it certainly doesn’t indicate a quest for knowledge.
5. Lack of curiosity
Research shows that curiosity is at the heart of intelligence.
When we stop asking questions, we stop learning. It’s that simple.
A friend of mine who works in education once told me that she can usually tell which students will struggle down the line—they’re the ones who never ask “Why?” or “How?” or “What if?”
The same is true for adults. Without curiosity, we have no incentive to explore new ideas or dive deeper into topics.
I’ve noticed this pattern in group workshops, too.
Some participants can’t wait to ask about the “why” behind certain branding strategies. Others just nod along with blank faces, never taking the conversation further.
The difference in results is huge.
Those who engage and question walk away with fresh perspectives and practical skills.
The rest often remain stuck where they are, which can be an indirect sign they’re not exercising their intellectual muscles.
6. Poor listening skills
One of the biggest indicators of someone’s mental engagement is how well they listen.
I don’t just mean hearing words; I mean truly absorbing what another person is communicating.
People who talk over others or zone out mid-conversation tend to miss crucial pieces of information.
It’s a habit that can reflect a lower level of emotional and cognitive intelligence.
Good listening doesn’t just help you learn facts, it also helps you understand context, emotion, and nuance.
Those layers are what make us truly informed and empathetic individuals.
7. Constant negativity
Ever notice how some people always have something negative to say?
Whether it’s a Monday morning or a sunny Saturday, they’ll find a reason to complain.
Chronic negativity can be a sign of limited perspective because it refuses to acknowledge solutions or silver linings.
It gets in the way of productive thinking and problem-solving, both of which are hallmarks of an agile mind.
8. Avoiding responsibility
We’ve probably all encountered that person who always blames something or someone else.
If a project fails, they say their teammates were incompetent.
If they lose a friend, they claim the other person was just “too sensitive.”
Shifting responsibility onto others can signal a lack of introspection.
True intelligence often includes emotional intelligence—recognizing our own role in outcomes, whether they’re good or bad.
I learned this lesson the hard way after a failed project at my old marketing job. I spent weeks insisting my manager gave me unclear instructions.
But the truth was, I never asked for clarity and I didn’t take the time to truly understand the client’s goals.
Once I owned my part in the failure, I realized how much I had to learn.
Embracing responsibility opens the door to new insights, while offloading blame keeps you stuck in the same spot.
Conclusion
We can all slip into one or more of these habits at times. What matters is acknowledging them and making a conscious effort to change.
Improving how we think is just as important as broadening what we know, especially if we’re serious about growing our personal brand and our sense of self.
I’ve caught myself in many of these behaviors before—overestimating my abilities, avoiding responsibility, or brushing off new ideas.
But I’ve discovered that the real beauty of intelligence is that it’s malleable. By staying curious, open-minded, and accountable, we can keep learning and evolving.
Thanks for reading, and here’s to continually sharpening our minds—one day at a time.
