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Cognitive biases affect everyone, though you may not always notice them.

These errors in thinking and reasoning happen as your brain tries to help you process and make sense of the vast quantity of sensory input you receive each day.

Your brain categorizes this information through the lens of your memories and experiences, which means it doesn’t always provide an accurate picture of what you take in at any given moment.

The horn effect, a type of cognitive bias, happens when you make a snap judgment about someone on the basis of one negative trait.

Say you meet your new supervisor, who’s bald, and immediately remember a bald middle school teacher who bullied and mocked you. Angry and afraid all over again, you distrust your boss immediately. Your bias led you to judge him by one trait — baldness — which your brain connected to that negative past experience.

This bias can show up in different contexts: when choosing foods to purchase, finding somewhere to live, or deciding whom to date.

At best, it can limit your options, but it can have more serious effects, too.

The horn effect offers a counterpart to the halo effect, a concept introduced in 1920 by psychologist Edward Thorndike.

He developed this theory after an experiment where he asked commanding officers to rate physique, intelligence, leadership, and character traits in soldiers before having any interactions with them.

His results suggested the officers tended to give soldiers with high ratings in one category, such as physique, high ratings in the other categories, as well.

One positive quality created a “halo,” so to speak, that extended over the soldier. That’s where the term “halo effect” comes from. Religious artists traditionally used halos to indicate that subjects were considered virtuous, godly, or good.

Starting to see where the horn effect comes in? That’s right: Thorndike found this effect also seemed to hold true for negative characteristics.

Officers who gave soldiers a low rating in one category tended to apply an assumption of inferiority across the board, giving them a “negative halo,” or horns — as horns traditionally represent devils in religious art.

Later research, including the work of psychologist Solomon Asch, supports the idea that people tend to form strong impressions of others based on the earliest perceived trait, whether that’s a stutter, a mental health condition, or even their name.

The horn effect is pretty widespread.

Perhaps you’ve passed on a grocery purchase because the label mentioned artificial flavors or genetic engineering. The product itself might have some positive attributes, but the negative trait you notice first colors your perception.

Ever used Tinder or another swipe-to-connect dating app? These apps, which encourage you to make a quick decision about someone’s worth as a potential partner based on appearance and attractiveness, have the halo-or-horn effect built in.

Certainly, attraction matters when it comes to dating, but people tend to confer other positive traits on people they consider attractive — traits they don’t necessarily have.

What’s more, one photo, especially a bad photo, typically doesn’t give a complete picture of someone. The horn effect, then, leads you to swipe left based on that first brief impression of “not my type.”

When this bias affects your ability to recognize someone’s positive traits or see the entire person beyond the “horn,” it can lead to prejudice and cause a lot of pain.

Consider these scenarios:

Starting a new job

On your first day, you arrive at your new office and begin meeting your coworkers. Among the blur of names and faces, one person in particular stands out: a member of your direct team who ends each sentence with a question mark and a nervous giggle.

“That’s really going to get on my nerves,” you think.

Other judgments might also come to mind. Perhaps you assume they have no confidence or wonder how they’ve made it so far in their career with such an unprofessional habit. Perhaps you even assume no one else likes their habit and worry this disdain will rub off on you if you get close to them.

So, you keep your distance, only interacting when absolutely necessary. As a result, you miss out on the opportunity to develop a solid working relationship, perhaps even friendship.

Meeting your partner’s parents

After several months of dating, you’re finally about to meet your partner’s parents.

You leave early to allow yourself plenty of time to find their house. Though you planned for traffic, you couldn’t have foreseen the crash that holds you up on the highway for half an hour. When you finally arrive 20 minutes late, you apologize and explain about the accident.

Your partner’s father welcomes you, waving your explanation aside, but their mother doesn’t seem to warm up to you. She hands you a cup of lukewarm coffee without asking if you want cream or sugar.

After serving everyone else a slice of pie, she leaves the tin on the table for you to get your own. When you talk about your interests and work accomplishments, she gives a dismissive sniff.

Back at home, you say, “I don’t think your mom liked me very much.”

Your partner sighs and explains. “It’s because you were late. She can’t stand lateness, so she’ll always hold that over you.”

“But it wasn’t my fault,” you protest. “I left way early. I can’t help that someone crashed.”

“Of course not, but she sees that as you being unlucky, and she doesn’t like that, either,” your partner replies.

Looking for a new home

Prejudice is one of the most serious implications of the horn effect. When people see certain physical characteristics, such as race, size, or gender, as negative, they often consider people with those traits inferior.

Say a white family viewing potential homes stops by a house in a quiet part of town. They know the neighborhood belongs to a school district with good ratings, and they’ve already checked to make sure it’s a low-crime area.

After admiring the fresh coat of steel blue paint and the neatly landscaped lawn, they notice children playing in the front yard of the house next door. A woman gardening in front of the house on the other side waves hello as they approach the porch. The family observes that the children are Black, the woman Hispanic.

After a few minutes, they leave. “The house was nice, and the neighbors seemed friendly,” one parent notes, “but I worry about the safety of the neighborhood.”

Here, the horn effect intermingles with racism. For this family, nonwhite neighbors appear to suggest “horns” due to their own prejudice. It’s not a huge leap to imagine that whiteness alone might extend a halo of safety over the neighborhoods they consider.

Horn and halo effects are pretty strong biases that can have major consequences.

Knowing they exist and learning to recognize them in your own impressions can make a difference, but this still might not help you avoid them entirely, one 1981 study suggested.

To avoid falling under the influence of the horn effect, try these strategies:

Remember people are complex

You can’t define anyone by a single trait, no matter how noticeable that trait is. Anyone you meet will have a personality defined by multiple characteristics, many of which you may not notice right away.

Take a look at yourself in the mirror. What does your reflection say?

Maybe you’re relaxing in comfortable sweatpants and a T-shirt that boasts a few holes and a questionable stain or two. You forgot to comb your hair, and your eyes look a little tired.

Someone could use those clues to decide you don’t care much about appearance. They might assume you’re sloppy, lazy, and can’t manage your time well — clearly you don’t get enough sleep and can’t be bothered to do laundry.

Of course, they have no way of knowing whether any of those things are true. They’re basing it all on their first impression.

In short, personality doesn’t always align with what appearance may suggest.

Challenge yourself to reconsider first impressions

Movies and TV often reinforce halo and horn effects. You’ve probably noticed that the most attractive characters tend to be the confident, successful, and wealthy ones.

Unattractive characters, on the other hand, may lack confidence and experience more failures than successes — unless they get a makeover or do something to change their appearance.

Your brain files away years of these messages and spits them back out as bias. When you meet someone you consider unattractive, you might, whether you consciously realize it or not, assume they’re single, unsuccessful, and have low self-esteem.

If you want to confront your bias, challenge yourself to identify two positive traits to counter that first negative observation.

These characteristics may outweigh the “negative” one and help rewrite your first impression. By specifically working to notice positive traits, you’ll also form a more complete understanding of that person.

Consider cold, hard facts

First impressions are subjective. They’re usually based on what you notice about someone rather than any actual information you have.

Think back to that middle school teacher who made you feel so awful. You might still feel pretty upset, even though years have passed. It’s understandable that bald men, like your new supervisor, might trigger a rush of fear.

To keep from being swayed by this emotional response, try a little logic.

Instead of actively avoiding your supervisor and putting your job in jeopardy, look for some objective evidence to support or refute the “horn” you’ve noticed.

Perhaps you immediately observe that he’s soft-spoken and friendly, two traits that go a long way toward setting him apart from your teacher.

Paying attention to facts can also help you make up your mind when trying to choose a product or make any other decision.

3 tips for objectivity in any situation

  • List pros and cons instead of deciding based on one factor.
  • Ask yourself what prompted your first impression.
  • Seek evidence to support patterns you notice.
Was this helpful?

Sure, the first thing you notice about someone might stick with you, but your first impression doesn’t have to be your final impression.

We all have biases. To challenge this one in particular, remind yourself the face someone shows the world at any given time may not accurately represent their actual self. Then, make an effort to truly get to know them.

Crystal Raypole has previously worked as a writer and editor for GoodTherapy. Her fields of interest include Asian languages and literature, Japanese translation, cooking, natural sciences, sex positivity, and mental health. In particular, she’s committed to helping decrease stigma around mental health issues.