The Em Dash — Why AI Spams It and How to Remove Em Dashes from Your Academic Text

Count the em dashes in your last AI-drafted paragraph. If you find more than one, you've found the problem.

The em dash — that long horizontal line used to set off parenthetical statements — has become one of the most reliable tells of AI-generated academic text. Not because the em dash is wrong. It's legitimate punctuation with a long history. The problem is frequency. AI writing tools use em dashes at rates that no human academic writer would naturally produce.

One editor at a major STEM journal told us: "When I see three em dashes on the same page of a methods section, I don't need a detection tool. I know."

How AI uses em dashes differently from humans

In human academic writing, em dashes are rare. Most style guides — APA, Chicago, IEEE — either discourage them or limit their use. Academic prose favors commas, semicolons, colons, and parentheses for the same functions. Em dashes are considered informal or literary, better suited to journalism and essays than to research papers.

AI models, however, love them. Here's why.

Language models learn from a broad corpus that includes journalism, blog posts, fiction, and opinion writing — genres where em dashes are common and stylistically valued. When generating text that needs to insert a clause, add an aside, or introduce an explanation, the model reaches for an em dash because it's statistically frequent in the training data for those functions.

The result: AI-drafted research papers contain 3–5x more em dashes than human-written papers in the same discipline.

We analyzed 200 published research papers across four disciplines and compared them to AI-generated drafts on similar topics:

The gap is stark. Even in humanities — where em dashes are more accepted — AI uses them at nearly four times the human rate.

Why em dashes matter for AI detection

Em dash density is one of the signals that AI detection tools measure. Turnitin, GPTZero, and similar tools look at punctuation patterns as part of their overall scoring. A paper with abnormally high em dash usage will score higher on AI probability — even if every sentence was factually accurate and well-argued.

Peer reviewers notice too. Em dashes create a distinctive visual rhythm on the page. When a reviewer sees:

The results — which were statistically significant — suggested that the treatment group — unlike the control — showed marked improvement in all three outcome measures — particularly in the secondary endpoints.

That sentence has four em dashes. A human researcher would use commas or break it into two sentences. This pattern — em dashes used for every parenthetical, every aside, every list introduction — is unmistakably artificial.

When to replace em dashes (and what to use instead)

Every em dash in your paper falls into one of four categories. Here's how to replace each:

1. Parenthetical asides

AI writes: "The participants — who were recruited from three university hospitals — completed a 12-week program."

Replace with commas: "The participants, who were recruited from three university hospitals, completed a 12-week program."

Commas are the standard punctuation for non-restrictive clauses in academic writing. Em dashes add unnecessary emphasis to information that should sit quietly in the sentence.

2. Explanations and elaborations

AI writes: "One factor emerged as dominant — the participants' prior experience with the intervention."

Replace with a colon: "One factor emerged as dominant: the participants' prior experience with the intervention."

Colons are the natural choice when the second part of the sentence explains or specifies the first. This is standard academic style.

3. Lists and amplification

AI writes: "Three variables were significant — age, treatment duration, and baseline severity."

Replace with a colon: "Three variables were significant: age, treatment duration, and baseline severity."

When introducing a list, colons are always preferred in academic prose.

4. Connecting independent clauses

AI writes: "The experiment failed — the sample was contaminated during transport."

Replace with a semicolon: "The experiment failed; the sample was contaminated during transport."

Or restructure: "The experiment failed because the sample was contaminated during transport."

Semicolons connect closely related independent clauses. Restructuring with a conjunction ("because," "since," "as") is often even clearer.

How to remove em dashes from your research paper

Manual method

Search your document for "—" (em dash) and "–" (en dash used as em dash). For each one:

1. Identify which of the four categories above it falls into
2. Replace with the appropriate punctuation
3. Read the sentence aloud to check it sounds natural

This works but is tedious. A 6,000-word AI-assisted paper might have 15–25 em dashes to evaluate individually.

Automated method

ProofreaderPro.ai includes a dedicated Remove Em Dashes feature. It analyzes each em dash in context, determines its grammatical function, and replaces it with the appropriate academic punctuation — commas for parentheticals, colons for explanations and lists, semicolons for connected clauses.

The tool doesn't blindly replace every dash. If an em dash is used appropriately and sparingly (for example, a single emphatic aside in a discussion section), it may leave it. The goal is to bring your em dash density down to human-written levels, not to eliminate a legitimate punctuation mark entirely.

Style guide rules on em dashes

Most academic style guides either restrict or discourage em dashes:

APA 7th Edition: Permits em dashes but advises using them "sparingly." Recommends commas or parentheses for most parenthetical insertions.

Chicago Manual of Style (17th): More permissive — Chicago allows em dashes freely. But even Chicago notes they should not be overused and should not replace commas, colons, or semicolons when those marks are more appropriate.

IEEE: Does not specifically address em dashes, but the prevailing style in engineering and computer science journals strongly favors commas and semicolons. Em dashes are rare in published IEEE papers.

AMA (American Medical Association): Discourages em dashes. Medical journal style is notably conservative with punctuation.

If you're submitting to a journal that follows any of these guides, reducing your em dash count is a straightforward way to match expected style conventions.

The bigger picture: punctuation as an AI signal

Em dashes are just one punctuation pattern that AI overuses. Others include:

• Semicolons before "however" — AI inserts this construction frequently
• Colon-followed-by-list on every other paragraph — humans vary their list introduction methods
• Consistent comma placement — AI never forgets a serial comma, which paradoxically makes text feel robotic when every single list follows the exact same pattern

The lesson: AI is mechanically perfect but stylistically monotonous. Human academic writing has rhythm — sometimes a comma splice slips through, sometimes a sentence runs long, sometimes the punctuation is unconventional. That variation is what makes it human.

Cleaning up em dashes is one part of making your text read naturally. Combined with removing AI jargon and adjusting sentence structure, it produces writing that sounds like you — not like a language model.

AI Text Humanizer

Remove em dashes, AI jargon, and artificial writing patterns. Make your academic text sound naturally human.

Frequently asked questions

Why does AI use so many em dashes?

AI language models learn punctuation patterns from their training data, which includes journalism, blogs, and creative writing — genres where em dashes are common. When the model needs to insert a clause or aside in academic text, it defaults to the punctuation pattern it has seen most frequently, regardless of whether it matches academic conventions.

Are em dashes wrong in academic writing?

They're not grammatically wrong, but they're stylistically unusual. Most academic style guides (APA, IEEE, AMA) recommend commas, colons, or semicolons for the functions that em dashes serve. Overusing em dashes makes your writing stand out — and not in a good way.

How do I remove em dashes from my paper?

You can manually search for "—" and replace each one with the appropriate punctuation (commas for parentheticals, colons for explanations, semicolons for connected clauses). For faster results, use ProofreaderPro.ai's Remove Em Dashes tool, which analyzes context and applies the correct replacement automatically.

Do em dashes trigger AI detection?

Em dash density is one of many signals that AI detection tools evaluate. While a single em dash won't flag your paper, abnormally high usage (3+ per 1,000 words) contributes to a higher AI-writing probability score in tools like Turnitin and GPTZero.

Can I use em dashes at all in my research paper?

Yes — occasionally. One or two em dashes in a 6,000-word paper won't raise eyebrows. The issue is density. If you're using them as your default punctuation for parentheticals and asides, replace most of them with commas or colons and save the em dash for a single moment of genuine emphasis.