In response to the em dash's association with AI, an agency created the "Am-dash"—a stylized dash. By using this new, rare mark via custom fonts like "Times New Human," writers can symbolically signal their work is human-authored, as LLMs are statistically unlikely to generate it.

To make early novels feel like true accounts, authors like Jane Austen used em dashes to redact sensitive information like names or locations. This stylistic choice mimicked protecting real identities, adding a layer of authenticity and intrigue for readers.

OpenAI has publicly acknowledged that the em-dash has become a "neon sign" for AI-generated text. They are updating their model to use it more sparingly, highlighting the subtle cues that distinguish human from machine writing and the ongoing effort to make AI outputs more natural and less detectable.

Medium's platform automatically converted double hyphens to em dashes for years, a stylistic preference of founder Evan Williams. This saturated its content with the punctuation mark, causing AI models trained on its vast corpus to replicate this quirk, effectively becoming a "tell" for AI-generated text.

Long before the em dash became associated with AI, it was criticized by literary figures for overuse. Jonathan Swift mocked it in the 18th century, and Lord Byron was panned for it in the 19th, showing a long history of grammatical purists viewing the mark as lazy.

The tendency for AI models to overuse em dashes may stem from their training data. To expand their knowledge, companies digitized millions of older books, including 19th-century classics where dash usage was at its historical peak. The models simply adopted this stylistic habit.

When an Economist writer pitted his own satirical column against one generated by AI, several colleagues mistakenly identified the AI's version as his. They found the AI's writing more coherent and, in some cases, more representative of his style, highlighting AI's shocking proficiency in creative and nuanced tasks.

While the em dash is a known sign of AI writing, a more subtle indicator is "contrastive parallelism"—the "it's not this, it's that" structure. This pattern, likely learned from marketing copy, is frequently used by LLMs but is uncommon in typical human writing.

Playwrights like Shakespeare used the em dash to guide actors on performance. It visually represented aposiopesis—speech deliberately broken off—to show thinking pauses, interruptions, or shifts in thought, adding a new layer of expressiveness to written dialogue.