My etiquette-minded aunt would have you believe there are two kinds of people in this world: Those who send thank-you notes, and those who do not.

Although I don't agree with my aunt on everything, I'm gonna have to go with her on this one.

People who express gratitude are my people. Whether it's a handwritten note after an interview or a quick email thanking a colleague for a favor, I believe saying "thanks" is always in order. (It vastly improves the response rates of your emails, too.)

Science is also on team thank you. In a recent study, published in Psychological Science, two psychologists explore why people avoid sending thank-you notes. I'll go into what they found, but the most important takeaway is this: Write the thank-you card. Don't worry about making it perfect.

People are far happier to receive them than you think, and doing it makes you feel good too. Your note doesn't have to be the best thing you've ever written. It can be short and still be sincere. The fact that you even took the time at all to send it will make the recipient "ecstatic," according to the researchers.

The New York Times wrote about the study and some of its findings. The Times explains that the researchers asked participants to write short letters of gratitude to people who had affected their lives positively in some way. People wrote to thank friends who helped them with the college admissions process, aided them in their job hunts, or supported them during difficult periods in their lives.

Here's why many people avoid writing thank-you notes. In their study, the happiness researchers found many of these common assumptions to be incorrect.

You think it won't really make a difference.

The researchers asked participants to rate how they thought people would feel when they received the notes. On a scale of one to five, with one being "meh" to five being "ecstatic," most assumed around a three. They thought it wouldn't matter all that much.

In fact, people were ecstatic to receive the notes. They gave strong fives all around. The researchers discovered that receiving a thank-you note has a far bigger impact on people's happiness than the senders had assumed.

You think it needs to be eloquently written.

Another reason people eschew writing thank-you notes is they don't know exactly what to say. They don't consider themselves good enough writers. How do you eloquently tell someone that you appreciate them? When it's hard to find the right words, you might avoid writing them at all.

But the researchers found the recipients of the gratitude letters didn't judge the writing. They cared more about warmth. People receiving the notes deemed the writing to be more competent than the people who wrote them did.

That's not to say that you should follow a fill-in-the-blank formula to drafting your thank-you notes. But it does take the pressure off to write something mind-blowingly epic. Just be sincere and say what you want to say. It will be appreciated.

You think it'll take too long.

It doesn't. Writing a thank-you note takes just a few minutes.

Amit Kumar, one of the co-authors of the study, said it took most participants five minutes or less. Your thank-you note doesn't need to be a novel. A few sentences or a short paragraph will do. In the grand scheme of things, it's a miniscule investment of your time that will have a big impact.

Even if you feel the window has passed on expressing gratitude for someone who made a small (or big) difference in your life, go ahead and write the note or send that email. It'll be the best five minutes of your day -- and will make theirs, too.