Search the archives of any newspaper in the state for the typo “Forth Worth,” and you’ll encounter plenty of results. It appears in the Dallas Morning News, the Houston Chronicle, and the Associated Press. The typo even makes it into headlines from its hometown papers, the Fort Worth Star-Telegram and the Fort Worth Weekly. (Lest you think that we’re picking on these outlets, the Texas Monthly archives return five pages of typos.)

One could blame a lack of diligence from reporters or gutted newsroom budgets stretching copy editors thinner than ever. But it’s a mistake made by non-journalists too—a cursory search on Twitter suggests that someone types “Forth Worth” about once every two hours.

To understand why so many people type “Forth Worth,” Texas Monthly reached out to Tom Stafford, a senior lecturer in psychology and cognitive science at the University of Sheffield, who studies the psychology of human errors. The British professor, who describes himself as “obsessed with these sort of errors at the moment,” had a great deal of perspective on what’s going on when we make this mistake, how “Fort Worth” is the typing equivalent of a tongue twister, and why it’d be hard to unlearn the habits that make this so common.

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Texas Monthly: Texas newspapers and magazines are full of people typing “Forth Worth” when they mean “Fort Worth.” Is there a reason this particular typo comes up over and over again?

Tom Stafford: I can tell you exactly what’s happening there. This is an example of a smart error, not a dumb error. A dumb error is when your finger slips or you hit the wrong key on the keyboard. It’s a simple mistake. The “Forth Worth” error is not that. It’s an error you only make because you’ve learned a lot about how language works. What you’re doing, when you type—especially if you’re a good typist and you type a lot—is that you don’t have to think about where the keys are on the keyboard. You have expectations about which letters will follow other letters. If you type i and n, then g is very likely to be the next letter, because we have a lot of words that end in “-ing.” That means that you don’t have to pay attention to every bit of what you’re doing. You can walk and chew gum, you can drive and listen to the radio, and your fingers take control of where the keys are and what order they’ll go, and you’re thinking about the meaning. So the “Forth Worth” error is just a little lapse, where your habit in typing has come out in the wrong place. You type “th” because that’s a very common thing to type. It’s in a lot of words. So you start typing “Fort,” but because you’re thinking of the meaning, it’s very natural for your fingers to automatically add the h.

TM: Are people anticipating the h at the end of “Worth” when they type it at the end of “Fort”?

TS: I’d need to do an experiment, but it sounds very, very plausible. To perform intelligently, you’re constantly trying to anticipate what’s required of you. Typing is very rapid, and as people type a letter, their fingers are already moving to the next letter. When people begin, they peck, but when you get skilled, you’re already thinking several letters ahead. If you do recordings of people’s fingers, you can see that they’re moving from the t to the h, even before they type the t. All it takes is a little attentional lapse, and your fingers do the right thing, just in the wrong circumstance.

TM: Is “Forth Worth” the typing equivalent of a tongue twister?

TS: Yeah, I guess “Forth Worth” is. There are certain sequences that are more confusing than others, aren’t there? We did this analysis where we downloaded the Wikipedia pages and looked for corrections. So if someone saves an edit on Wikipedia where they type “Forth Worth” and then immediately save a correction as “Fort Worth,” you can identify that as a typo because they’ve just changed one letter. In our experiment, we use that to identify particular sentences that are more likely to generate these kind of errors. These kind of errors are common in typing, and once you start studying this stuff, you find that you make these errors all the time. I mean to write “definite” and I write “definitely” or I mean to write “data” and I write “date.” I’m constantly adding plurals or apostrophes to words. It’s a bit of a nightmare. Once you start thinking about this stuff, you see how often you do it.

TM: If you want to stop making this mistake, it sounds like the best way is to be mindful of the combination of words that lead you to make these typos.

TS: It’s hard because, ultimately, it’s a product of your skill. The better a typist you are, the more typing you do, the more at-risk you are of making this error. So you could slow down, but that has its own costs, doesn’t it? But remember that these errors don’t indicate that you’re losing your mind—they’re a normal part of being a good typist—and let’s pay the proofreaders and copy editors properly.

This interview has been edited for clarity and length.