What Makes Some People So Nice, and How They Stay That Way
Being nice has its benefits, and the best part is that it's cheap.
Updated February 12, 2026 | Reviewed by Lybi Ma
Highly agreeable people tend to be nice to others, even when they’re in a bad mood. As one of the five basic personality traits, agreeableness tends to attract less attention than, say, neuroticism or extraversion . Yet, in daily life, agreeableness can be the stealth tool that gets you farther than you might realize.
Kate is one of those super-nice people. No matter what, she always seems to be in a good mood, and as a result, nothing seems to bother her. In what seems like a typical experience for her, an online merchant overcharged her for a sale item. When calling in to contest the charge, she never once said anything to the customer service agent that could remotely be thought of as angry or aggressive. Not only was her situation resolved, but the agent offered her an extra discount on her next purchase. Being nice clearly paid off.
How Agreeable People Stay So Agreeable
You might wonder how agreeable people become so nice. Were they born with this quality, or did they somehow acquire their high levels of this trait through experience? A 2024 study by Western Illinois University’s Eugene Mathes on the personality trait of agreeableness suggests that through their selection of experiences, people who start out nice might only become nicer. Like Kate, could good things happen to them that give them an even kinder way of treating others?
Mathes suggests that the reason agreeable people stay, if not become, more agreeable is because it makes them happy. Known as the “trait-consistent affect regulation hypothesis,” this idea has mainly been tested concerning the personality qualities of extraversion and neuroticism, not agreeableness. In his words, “Neurotics seek affective states that are negative while extraverts seek affective states that are positive.”
How might this work for agreeableness? There are three possibilities. The first, or “epistemic,” is that the world makes sense to nice people when they experience feelings of love and kindness. The second option is based on a performance rationale and suggests that agreeable people perform better when their feelings match their traits. Finally, the social explanation argues that nice people like to feel nice, which they do when others seem to like them.
Putting all these possibilities together, the bottom line remains that niceness begets niceness by stimulating positive emotions. If nice people are forced to be nasty, they’ll feel miserable either because this doesn’t match their true selves or because people actually reject them.
Testing the Agreeable-Affect Link
Across a series of two studies (all using undergraduate students), Mathes tested the trait-consistent hypothesis by seeing whether people high on agreeableness would choose experiences that reinforce this quality, hence keeping the cycle of niceness breeding niceness going. He also tested the converse of the agreeableness effect by looking to see whether people low on agreeableness would continue to charge up their hostility and anger in their choice of experiences.
The Western Illinois University researcher used entertainment choices as the framework for the study. Very simply, he tested whether nice people seek “feel good” forms of music, movies, and TV shows while their more aggressive counterparts seek forms with violent content.
To see how this worked, list your three favorite songs, movies, and TV shows. Then ask how agreeable (or aggressive) they make you feel. Examples from the study included rating items such as: “This song makes me feel loving.” “This song makes me feel angry.”
Standard personality trait rating scales served as the measures of agreeableness and aggressiveness. The basic analyses consisted of simple correlations between the personality and entertainment preference scales.
As Mathes predicted, people with high levels of agreeableness preferred entertainment that made them feel more agreeable, and those low on agreeableness sought the opposite forms of entertainment (as a side note, he controlled for gender ). As you might be thinking, from this correlational study, it’s not clear whether the “nice” entertainment choices led people to be nicer or vice versa. There could even be some third, unmeasured, influence.
However, if we think about the niceness-entertrainment choice relationship as an ongoing reciprocal process, the findings suggest that whether people start out being nice and then get nicer through their entertainment choices, or vice versa, the causal chain isn’t that important. At some point, highly agreeable people figure out ways to make themselves feel better by seeking experiences that tap into this trait.
Why It’s Worth Cultivating Agreeableness
This study shows that personality and the choice of experiences can reinforce each other either for good or for bad. Returning to the case of Kate, she likes to be nice because it makes her feel good. The social learning explanation of the trait-consistency hypothesis rests on the premise that you’ll feel good when you’re being nice because other people are nicer to you in return.
It then follows that, through social learning, you’ll be reinforced for your nice behavior, perhaps in concrete ways. Kate got an offer she most likely wouldn’t have if she’d been grumpy and difficult to that customer service agent.
You can try this experiment yourself. The next time you have to put in a call or visit a store with a valid gripe, add some extra charm. Then see what happens as a result. Because many customer service people are forced to be nice, they’re often looking for relief from their stress (what’s called “ emotional labor ”). When they’re having a bad day, or even if they’re not, a customer who’s courteous and friendly will seem like a gigantic relief. Niceness will beget niceness all around.
To sum up, being nice does not have to cost you anything, and it can also lead to rewards, both tangible and emotional. Not only will your life be better, but so will the experiences of those whose lives you touch.
Facebook /LinkedIn image: Vulp/Shutterstock
Mathes, E. W. (2024). A test of the trait-consistent, affect regulation hypothesis with respect to agreeableness. Current Psychology: A Journal for Diverse Perspectives on Diverse Psychological Issues , 43 (29), 24638–24646. https://doi.org/10.1007/s12144-024-06177-0
Share this post Facebook Bluesky Linkedin Email
There was a problem adding your email address. Please try again.
By submitting your information you agree to the Psychology Today Terms & Conditions and Privacy Policy
Susan Krauss Whitbourne, Ph.D. , is a Professor Emerita of Psychological and Brain Sciences at the University of Massachusetts Amherst. Her latest book is The Search for Fulfillment.
Get the help you need from a therapist near you–a FREE service from Psychology Today.
This article is part of the Bringwise Psychology Journal — daily insights on human behavior, mental health, and personal growth.