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You've probably done this a thousand times, typed T-E-H instead of T-H-E. Or maybe you're always adding an extra "i" to the word "application," even though you really do know how to spell it.

No matter how many years you've been typing on a keyboard, the same mistakes keep happening. And it's not because you're sloppy. It's actually because when we type, our brain is doing most of the work without our conscious input.

At least on a computer keyboard, which is how all this research was done. In a series of experiments published in 2014, researchers based in Tennessee tested typists' knowledge of where certain keys are on the keyboard. They asked skilled typists, ones who had some formal training and lots of experience, to recall the locations of certain keys on the QWERTY keyboard.

That's the style of keyboard layout that's probably in front of you right now, or pops up on your phone or whatever. Just look at the first few letters. What the researchers found was that skilled typists didn't have a lot of familiarity with where the keys were, and couldn't even fill in all of the keys that were supposed to be there.

The researchers also tested the skilled typists on a Dvorak keyboard, one with a different layout than the familiar QWERTY they'd been trained on, essentially turning them into beginner typists. And they found that it didn't matter whether they had been typing with a given layout for years or a couple of hours, their knowledge of key placement was equally bad. You're probably saying to yourself, that can't be right.

You type on a keyboard every day, so surely if you tested yourself right now you'd be able to give a detailed description of it, right? Okay, let's do it. Imagine a keyboard.

No! Don't look down! Imagine it.

Got it? Can you picture where the “A” key is? How about the “R” key?

If I were to ask you where it is, could you tell me the exact location of the “V” key? You're probably struggling a little bit. The reason you might struggle to remember exactly where the “V” key is, or whether the President faces left or right on a quarter, for that matter, has to do with how your brain remembers things.

Our long-term memory works in two ways. It recalls things either explicitly or implicitly. Explicit or declarative memory is when you remember you have a dentist appointment on Tuesday.

It's a conscious recollection of something like facts, names, or events. In other words, it's on-purpose remembering. Implicit or procedural memory is the unconscious memory of a skill or task, like typing.

Implicit memory is useful because it allows you to do something without having to re-learn it every time. Your implicit memory is how you know how to ride a bike even if it's been a decade since you were last on one. So the reason you might suck at remembering if the # is on the 3 or the 4 key is because once we become familiar with typing, our brain unconsciously knows what keys to press.

However, this doesn't fully explain why our brain makes dumb typos like N-A-D instead of A-N-D. And that's because when it comes to writing, there's a lot of different brain functions that are going on. First there's something called hierarchical organization.

When a task becomes routine, our brains like to organize it into categories and subcategories. So when it comes to typing, our brains start with the word, then move on to the spelling, and then to the keys we need to press. One study published in 2010 that looked at this found that this hierarchical organization can actually cause us to press two keys at the same time.

Thus the typos. Research going back as far as 1980 has found similar results. When we type, we're already moving on to the next letter before we finish typing the first one.

Although this only seems to happen when we're typing words that use two hands. And while that doesn't tell us for sure why we type “t-e-h” and “n-a-d,” those are two-handed words! Hierarchical organization is what's driving our brains to group the letters in a word together, but we also do it at a motor control level.

In order to make our movements more efficient and free up thinking space, we do something called motor chunking. Motor chunking is when you take a movement, like typing, and string it together into longer, more fluid sequences. For example, think of the way you dial a telephone number.

If it's a number you've never called before, you probably punch it in One. Number. At.

A. Time. But if it's your home phone number you probably type it in quickly: area code, then the first three numbers and then the last four.

Or however phone numbers are split up in your area. The same thing happens when we type words on a keyboard. As we get familiar with the process, we start to string together movements so we can type faster, more efficiently, and we don't have to think so hard about what we're doing.

And the “not thinking so hard” could well be contributing to those annoying typos. When we're writing, we're not really focused on the individual letters of the word. We're focused on the bigger picture, the meaning of what we're writing.

One study from 2013 looked at what happened before and after participants made typing errors. The researchers observed that the speed of typing changes in conjunction with mistakes. They concluded that this shows that there is potentially a break in your train of thought.

This focus on the greater meaning of what we're typing might also be why we're pretty bad at catching our own typos. Since we already know what we're trying to say, a flipped letter here and there isn't going to jump out at us. Which is why we have spell check.

And editors. Or at least a friend who's willing to look over stuff for us. So don't sweat the typos too much!

We don't really know how to type, but we make it happen anyway. Thanks for watching this episode of SciShow Psych. We know someone who's pretty good at typing and also writing, it's Hank Green!

And his novel An Absolutely Remarkable Thing is now out in paperback. So if you're the kind of person who waits for the paperback, the wait is over. Check it out everywhere you find good books! [♪ OUTRO].