If a speaker uses a dramatic pause, a writer seeking to reproduce this in dialog may use an em-dash (the longer dash). The example would be rendered as:
Let me introduce—John
some style guides advise space on each side of an em-dash, as:
Let me introduce — John
In either case this represents a significant pause, longer than the pause a comma or semi-colon would indicate. I have seen it used in dialog with some frequency.
Several sources support this use of an em-dash, or something like it:
- The page "em-dash" from The Punctuation Guide states:
The em dash can be used in place of a colon when you want to emphasize the conclusion of your sentence. The dash is less formal than the colon.
- After months of deliberation, the jurors reached a unanimous verdict—guilty.
- The white sand, the warm water, the sparkling sun—this is what brought them to Fiji.
Em dashes can also signal an interruption or a sudden change in the direction a writer was heading with a particular sentence. This technique is best suited for creative or informal writing. If you use it in academic writing, you might look unsure of yourself. Consider the examples below:
- Mary, could you—no, Mikey, don’t touch the sharp knife!—Mary, could you please set the table?
- Dinner is at 6:30—not 6:29 or 6:31.
- Where the heck is my—wait, what was I looking for?
- Would you please—oh, never mind.
An em dash can also be used to mark a break in a sentence in place of a semicolon or colon. In this context, dashes are often used for emphasis or to signal a change in tone:
There was no arguing with her—she was set in her opinion.
- An em dash can mark an abrupt change or break in the structure of a sentence.
Mabel the Cat was delighted with the assortment of pastries the new bakery featured, but Harry the Dog—he felt otherwise.
- An em dash can indicate interrupted speech or a speaker’s confusion or hesitation.
- Harry’s bafflement was apparent. “That the bakers fail to recognize the crucial importance of the cheese Danish—”
- “Of course you have a point,” Mabel murmured. “That is—I suppose it is concerning.”
An em dash can replace a colon that introduces additional information at the end of a sentence. Again, this is often done to draw a reader’s attention.
- After his long journey, Gawain finally found out what was in the lockbox—nothing!
- The Narrator finally realized the truth—Tyler Durden wasn’t real.
- After days of deliberation, the jury came to its final verdict—not guilty.
The em dash in American English is a punctuation mark that helps to convey emphasis, introduction, interruption, or a swift change of thought. In doing so, the em dash acts similarly to commas, semicolons, colons, and parentheses.
Sometimes we may write as we think or speak: in other words, in a nonlinear way. We might start with one thought and abruptly shift to another. In writing, the em dash allows us to express such rapid changes:
I just wanted to say—oh, it’s nothing.
Just as em-dashes add emphasis when they take the place of commas or parentheses, so do they add emphasis to an already emphatic punctuation mark: the colon. You want to be sparing in your use of an em-dash in place of a colon, and remember that by using an em-dash instead of a colon, your style becomes less formal. If that’s your intention and you want to add special emphasis to a word or phrase, then use the em-dash. Take the following sentence as an example.
After 1,000 miles of sputtering along in his tiny Honda, Dennis could think only one thing as he approached his driveway—home.
A pause in speech can a;so be shown with an ellipsis (...). But that is more often used for broken speech, or an involuntary pause, not and intentional dramatic pause.