If you overheard a conversation on a bus, do you think you could tell from the words that were used and the topics discussed, the personality of the people who were chatting? What about if I showed you a short story? Could you glean something about the character of the author from their language?

We’re often reminded “choose your words carefully” – well it turns out the words themselves may reveal far more than what we’re actually trying to say. There’s mounting evidence that our personality is written, quite literally, in the language that we use, from the tweets we send to our choice of email address.

Not all findings are particularly surprising. Those who score highly on extroversion really are a lot louder and chattier than their more introverted peers. They also tend to speak more quickly. Female extroverts, but not males, are more likely to have group chats, while introvert men (but not women) spend more time talking to themselves.

But introverts and extroverts also use language very differently. A few years ago, a group of researchers led by Camiel Beukeboom at VU University, Amsterdam, asked a group of 40 volunteers to look at photos of different social situations and describe out loud what was going on. They found that extroverts’ language tended to be more abstract and “loose”, while introverts spoke in more concrete terms. In other words, introverts tend to be a lot more specific.

Extroverts say: “This article is excellent”

Introverts say: “This article is very informative”

In line with this, other research has found that introverts tend to use more articles (the/a) – which, by definition, refer to individual objects or events. They also tend to be more cautious in their language: that is, they use more hedging (perhaps, maybe), and more quantifiable terms, such as referring to specific numbers.

Extroverts say: “Let’s get some food”

Introverts say: “Perhaps we could go for a sandwich”

All of this makes psychological sense. Most extroverts enjoy the fast life, being more likely to drink, sleep around and take risks than introverts; every time they open their mouths, too, extroverts are prepared to take greater risks with the accuracy, spontaneity and reach of what they say.

The links between personality and language also extend to the written word. When Jacob Hirsh and Jordan Peterson from the University of Toronto asked students to write about past experiences and future goals, they found that those who scored higher in extroversion tended to make more mention of words pertaining to relationships, which makes sense, the researchers said, as extroverts are “active social explorers”.

But it’s not just about extroversion vs introversion. Their language also revealed other aspects of their personalities – including how open-minded they were (the liberal used more words pertaining to the senses), how neurotic (the highly strung referred more often to emotional angst) and how conscientious (more diligent students used more achievement and work-related words).

The neurotic say: “I carry around a monstrous sadness”

The open-minded say: “You just need to be heard”

The conscientious say: “We can work on it”

Personality also shines through in creative writing. In 2010, a team of German psychologists gave over a 100 student participants five words as prompts (“plane crash,” “parlourmaid,” “fireworks,” “Middle Ages,” and “supermarket”) and then asked them to write a short story that included each of these words. This time more open-minded participants produced more creative stories, while more agreeable participants wrote stories with a more pro-social vibe. What’s more, when a separate group of participants were shown the stories and asked to judge the traits of the authors, they did a pretty good job, at least for the traits of openness and agreeableness.

Most of these studies have looked at the language we use in isolation. But what happens when we chat together? One study found that if you put a bunch of introverts in a room together, they’ll probably end up talking about problem solving (“I've got to look for an apartment because my room mates are driving me nuts”).

In contrast, when extroverts talk to each other they cover a wider range of topics and display more “pleasure talk”, such as “I like jogging” and “Steinbeck is wonderful”. Again this is consistent with what most people already know: in life extroverts tend to be more focused on simply enjoying life.

Of course, these days we also spend our days sending emails, blogging and posting updates to Twitter. And – you guessed it – it seems we betray our personalities in these digital forums too.

By analyzing the content of nearly 700 blogs comprising hundreds of thousands of words, researchers at the University of Texas at Austin found that the words people used matched up to the way they reported their own personality: for instance, those who viewed themselves as more agreeable used fewer swear words.

But the team went further, even pinning personality traits down to the use of specific words. High scorers on “openness to experience” were more likely to use the word “ink” and – predictably – extroverts are more likely to say the word "drink". 

It’s a similar story on Twitter. Other research has found that extroverts tend to refer to positive emotions and social situations more frequently, while high scorers in neuroticism (or emotional instability) tend to use more first-person singular pronouns, like “I” and “me”. The latter fits with the finding that those experiencing emotional turmoil use these words more liberally.

Extroverts say: “We’re so happy!”

Neurotics say: “I’m having a good time”

Incredibly, these personality associations are so consistent, the same study found that volunteers were able to accurately guess the personality of a total stranger  – how neurotic and agreeable they were – just by reading their tweets. 

In fact, it seems we can’t help trying to decipher the personalities of the people we meet from the language they use. We’re constantly judging – right down to a person’s digital labels. Those with more numbers in their email address, for example, are seen as less conscientious. Meanwhile we tend to think that humorous addresses are more likely to belong to extroverts (though this isn’t true).

The idea that we reveal something fundamental about ourselves every time we speak, write or tweet, is a little disconcerting – especially if you generally prefer to keep your character profile to yourself. But it also offers an opportunity to change the way you’re seen by others. In some situations, such as in a job interview or the early stages of dating, it should be possible to adopt a desirable persona, just by changing the language you use. If that’s you I’m guessing your personality is a touch Machiavellian. 

I think I’d better stop writing now before you discover what mine is.

Dr Christian Jarrett edits the British Psychological Society's Research Digest blog. His next book, Personology, will be published in 2019.

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