It's happened to all of us. In the middle of a conversation, you suddenly hit a vocabulary wall. "What's that word?" you think. You know the word. But you can't say it. It's stuck there on the tip of your tongue.

There's a scientific term for this phenomenon, which is—you guessed it—tip-of-the-tongue syndrome [PDF]. It's so common that most languages have given it a term [PDF]: Koreans say a word is "sparkling at the end of my tongue," for example, while Estonians describe the missing word as being "at the head of the tongue."

For Karin Humphreys, tip-of-the-tongue syndrome is very real, both as a personal experience and a topic of research. "I'd find I would get it on the same name or same word over and over again," she tells Mental Floss. Out of desperation, she'd look up the word online, or a friend would come to her rescue. "You feel you're never going to forget it again, because the relief is just so palpable. And then I'd find myself a week later in a tip-of-the-tongue state on the same word again, which is even more frustrating! It got me thinking, 'Why the heck is this happening?'"

Luckily, Humphreys is in a unique position to answer that question. She's an associate professor at McMaster University in Ontario, Canada, who studies the psycholinguistics of language production. "I'm particularly interested in all kinds of language errors that we make," she says. In a series of six studies, Humphreys and Maria D'Angelo, a postdoctoral fellow at Rotman Research Institute, looked at why we experience tip-of-the-tongue (TOT) over and over again—and how we can prevent it.

WHY DO TIP-OF-THE-TONGUE STATES OCCUR?

Translating thoughts into words is a complex process—one that we take for granted because it usually happens effortlessly. The brain translates thoughts from abstract concepts into words and then attaches them to the appropriate sounds. Voilà: we speak. In TOT states, this process gets interrupted. "Word retrieval normally goes smoothly and easily, but in this case the system breaks down and you get stuck partway through," Humphreys says.

Why this mental process is interrupted isn't entirely clear. One study links TOT states to caffeine intake. Humphreys says they often happen when we're tired, and are more common when we're trying to recall proper names.

Frustratingly, the more we think about the missing word, as we are inclined to do, the more it eludes us. But struggling with it only to be given the answer by the Internet actually doesn't do us much good in helping us recall the word later. In fact, Humphrey's research suggests it basically ensures you'll forget it again.

Working with undergraduate volunteers, she triggered TOT states by providing a series of definitions and asked participants produce the corresponding words. To induce a tip-of-the-tongue response, the words have to be relatively uncommon with few synonyms.

A sample definition: "What do you call the sport of exploring caves?"

If the definition stumped the participant, sending them into a TOT state, they were given a bit of time to think on it. If they still couldn't remember the word, researchers would give them the answer. (The sport of exploring caves is "spelunking.") The experiment was repeated with the same participants, definitions, and words in various intervals to see if the time between tests would change whether or not participants could recall the words next time. But it didn't matter if the test happened a week later or five minutes later. Many people repeatedly experienced TOT states on the same words.

"Our results support the idea that making errors tends to reinforce those errors, making them more likely to reoccur," the authors write. In other words, every time you forget Liam Neeson's name and resort to looking it up on IMDB, you're reinforcing your mistake, digging the mental groove of forgetfulness even deeper.

"If you keep going down that pathway, it digs that path a little bit more you're a little bit more likely to fall into that same rut later," Humphreys says.

HOW CAN WE PREVENT IT FROM HAPPENING?

The good news is that the new studies offer a potential solution. Humphreys found that when participants managed to remember the word they were struggling with on their own, instead of just being told the answer, they were less likely to forget the word on the next test. And when volunteers were given a phonological clue, like the first few letters of the word, they were almost as likely to remember the word later as if they'd figured it out it on their own.

So what's so bad about just being told the answer? "Our preferred interpretation is that resolving a TOT activates the same processing pathway that is required to later retrieve and produce that word," the authors write. "In contrast, simply reading and recognizing the word does not activate the exact pathways involved in producing that word."

So the next time you're tantalized by a word on the tip of your tongue, recruit someone around you to help you out. Explain what you're trying to say and ask them to give you a clue. "We're not doomed to repeat our errors," Humphreys says.