[♪ INTRO ].

So, Y'know um when you say something, and...you're like stumbling a little bit because you are not uh, totally sure what you wanna say that y'know other words will find a way in? You don't have to search hard to find recommendations that using filler words like “um,” “uh,” “like,” and “y'know” will make you seem nervous and less competent.

So you'll tank that job interview or speech you're giving. And there is some research showing that using a lot of filler words reduces speakers' credibility. But it's actually useful in some situations, like day to day conversation.

To set the record straight, it's not weird to use filler words. Most people do. Some frequently-cited research from the 1950s found that people slip up while they're talking about once every 4.4 seconds.

And it's not just young people either. A 2014 study of 263 people ranging from age 17 to 69 found that people of all ages and genders used space-filling words like “um” and “uh” at about the same rates. Different age groups preferred different words, though.

For example, college students use "like" more often than older groups of adults. And just because those millennials are saying “like” more often doesn't mean they're destroying language or that these words are meaningless. Most of these filler words can convey important things in conversations, which psychologists study by recording people talking and analyzing the transcripts for patterns.

When people are thinking of what they're going to say next, that's where "uh" and "um" come in. These are called filled pauses and signal to listeners that, no, you didn't stop talking, you just need a second to come up with with the right words. Some research has even shown that people use “um” more when they're being honest.

When people are asked to say lies, it's as if they need to rehearse them, and they don't do that stopping-to-think thing that makes people say "um" as often as in normal conversation. People tend to use other filler words, like "you know" and "like," in consistent ways, too. They use "like" when the words that follow aren't precise.

For example, people are much more likely to use it before a quantity, as in "that plane ticket cost me, like, three hundred bucks!" They probably don't remember an exact number, so the language communicates that. But people are unlikely to put an "um" or "uh" in that sentence. They probably have a lot of experience saying the words for numbers, and don't need the extra pause to remember “three hundred.” After all, they've been practicing numbers since they were, like, three!

And "you know" is used to confirm that the listener understands—or is at least still paying attention. Even if the listener just responds nonverbally, like with a nod. All this research means that filler words are meaningful and useful in conversations, even if they're not the central part of the message.

So why is everyone trying to get rid of them? There's some basis for this advice, but it's more complicated than you'd think. For example, one study from 2013 looked at 1380 recordings of telemarketers asking people to participate in surveys.

For the most part, when the person calling used more filler words, they were less successful in getting people to participate. But there was an important exception: the people who used no filler words performed worst of all. The researchers thought this was because using a ton might've made people sound a little incompetent.

But using none probably made people sound robotic, like they were reading from a script instead of being engaged in a conversation. So eliminating them entirely probably isn't a good idea, either. It also seems like people have the worst impression of filler words if they're on the lookout for them.

To demonstrate this, in a study from 1995, researchers took a recording of a radio talk show caller and manipulated it in a couple ways, either replacing his filler words with silence, or cutting the gaps out entirely. Over 1000 participants were a part of this study. Each person listened to one of these three recordings.

And when everyone was asked afterward to rate how frequently the speaker used filler words, they all gave about the same rating. Unless they were told to pay attention to the speaker's style—then they noticed the filler words a lot. But if they were told to specifically pay attention to the arguments, listeners seemed to ignore the filler words entirely.

When subjects were asked to rate the speaker on things like how eloquent or relaxed they were, the no-gap recording made the speaker seem best. But if there were gaps, it was better to have them filled with ums and uhs. Also, filler words can be an important part of listening.

One 2004 study found evidence of this by analyzing conversations at a speed dating event. Women reported liking men more when they used short, filler-word interjections like "uh-huh" and "okay" while listening. Although these signals didn't seem to matter much the other way around.

And a 2011 study found that telemarketers who used these kinds of interjections while listening were given higher ratings of competence by a panel of participants. So if you're using filler words way more than most people, it might not be a bad idea to practice cutting back a bit. But there's no reason to get rid of them entirely.

They're probably helping your conversations along. Thanks for watching this episode of SciShow Psych! If you want to learn more about the psychology of language, check out our other video about how swearing could potentially help with pain. [♪ OUTRO ].