Is someone using AI to text you? What you can and can't tell

Usually you can’t tell for sure whether someone is using AI to text you. Detectors are a poor fit for messages this short: OpenAI withdrew its own AI text classifier on 20 July 2023 “due to its low rate of accuracy”, after warning it was “very unreliable on short texts (below 1,000 characters)”. And people’s instincts are no better. What you can do is notice patterns, ask, and judge the person by what they do next.

This page covers why detection fails, the signs people point to and what else each one can mean, how to ask without accusing anyone, when to actually worry, and where reasonable AI help ends. It’s written for anyone wondering about a friend, a partner or a match.

Why AI detectors are unreliable on text messages

OpenAI’s own detector wasn’t accurate even on longer text, and texts are far shorter. OpenAI’s numbers for its own classifier, published in January 2023 and still on its announcement:

• It correctly flagged only 26% of AI-written text as “likely AI-written”.
• It wrongly labelled human writing as AI-written 9% of the time.
• It was “very unreliable on short texts (below 1,000 characters)”. A long text message is a few hundred characters.
• “AI-written text can be edited to evade the classifier.”

Less than six months later OpenAI took it down. OpenAI also wrote that its classifier’s reliability “typically improves as the length of the input text increases”, and that “it is impossible to reliably detect all AI-written text”. A two-line message gives any detector very little to go on. There’s a privacy cost too. Pasting someone’s messages into a detector or chatbot sends their words to another company without their say (our privacy checklist for AI and messages covers what happens to that text).

Why your gut isn’t reliable either

Researchers at Cornell and Stanford ran six experiments with 4,600 participants, asking them to spot AI-written self-presentations in professional, hospitality and dating contexts. People couldn’t do it (Jakesch, Hancock and Naaman, PNAS, 2023). Worse, they relied on “intuitive but flawed heuristics”, such as assuming first-person pronouns, contractions or talk about family meant a human wrote it. Because those cues are predictable, the authors showed AI text can be made to read “more human than human”.

So if you’re sure you can always spot it, the research says you’re probably wrong in both directions: missing AI text, and accusing real people.

The signs people notice, and what else they can mean

None of these proves anything alone. A pattern across many messages, plus other changes, is worth more than one message.

Sign	Why people suspect AI	What else it can mean
A sudden change in style: longer, perfectly punctuated, no typos	Chatbots write clean, complete sentences	They’re on a laptop instead of a phone, dictating, or taking care over something that matters
Warm but generic replies that don’t mention anything you said	AI fills gaps with pleasant filler	They’re tired, busy or skimming
Long, polished replies that arrive very fast	Faster than most people type	They type fast, or wrote it earlier
Therapy-speak (“I hear you”, “that’s valid”) and neat lists	Common in chatbot answers	Some people really talk like this
Em dashes and formal phrasing	Often called an AI tell online	Plenty of people have always written this way
Answers that miss details from earlier in the chat	AI drafts often ignore context	Not reading closely, or replying to the wrong chat
The voice in texts doesn’t match the person on a call or in person	Texts drafted by something else	Many people write more carefully than they speak

The last row is the most useful, and it leads to the best test there is: talk in a way AI can’t stand in for, on a call, a voice note or in person.

Does it matter if they used AI?

That depends on how much they used. AI help ranges from spellcheck and suggested replies, to a draft the person rewrites, to a bot writing everything and sending it. Most people’s line is somewhere in that range:

• In the Kinsey Institute’s Singles in America study, funded by Match (about 5,000 US singles, March to April 2026), 39% had used AI in their dating lives, and 30% objected to someone using AI for all their conversations (Kinsey Institute via EurekAlert).
• In a study of suggested replies led by Cornell researchers, suggested replies made conversations faster and more positive, and people rated a partner who used them as closer and more cooperative. But people were judged more negatively when their partner suspected they were using them (Hohenstein and others, Scientific Reports, 2023).

So suspicion itself does damage, whether or not it’s true. That’s a reason to ask rather than stew. (For the dating side of this debate, see is using AI on dating apps cheating?)

How to ask without making it weird

Ask about the message, not about their character, and leave room for a normal answer. Some ways to say it (example messages, made up for this guide):

• Light: “Ok, that reply was suspiciously well written. Did you have help? Haha”
• Curious: “Random question: do you ever use ChatGPT or something to help with texts? No judgement, I’m just curious.”
• Direct, with a partner or close friend: “Your messages lately feel a bit different from how you usually talk. Is everything ok, or are you using an app to help write them?”
• With a match: “Honest question before we meet: are these your words? I’d rather get to know the real you, typos and all.”

Then listen. “Yes, I use it to fix my spelling” or “I was nervous and wanted to get it right” are common, human answers. If someone gets defensive, that tells you something too, but not necessarily that they used AI.

When to actually worry

The things that should worry you aren’t about AI at all. They’re the behaviours behind romance scams, whoever or whatever writes the messages. The FTC’s list of warning signs includes:

• Wanting to move off the dating app quickly to email, calls or another messaging app.
• Saying they can’t meet in person, often because they’re living or travelling abroad.
• Asking for money, gift cards, crypto or an investment, often with an emergency attached.

Tinder’s safety tips say the same: keep conversations on the app while you’re getting to know someone, and never send money. If those signs appear, stop and report the account, AI or not.

When AI help is fine

Using AI to fix spelling, to reword a hard message, to translate, or to get unstuck on a reply you then rewrite in your own words is a far cry from letting a bot hold the conversation. The useful line is authorship: the words that go out should be yours, and you should be the one who sends them. Our guide to AI as a wingman, not a ghostwriter draws that line in detail.

Dating apps draw it more strictly. Tinder’s Terms of Use (effective 5 March 2026, §2c item 22) and Hinge’s Terms (§2c item 22) ban third-party apps or services that directly interact with the service without written consent, “including but not limited to artificial intelligence or machine learning systems”. Hinge also bans content you didn’t write yourself or that was automatically generated, unless it authorized it. Is it against Tinder’s rules to use AI? explains what that covers.

Where we stand

To be straightforward about our own part in this: Tera Chat for Mac, a free app we make, drafts replies in your own texting style across iMessage, WhatsApp, Telegram, Instagram and Tinder. It doesn’t detect AI in messages you receive. Tera Chat also connects to your Tinder account, so it’s the kind of third-party tool the dating apps’ terms above cover. Our line is that you stay the author: by default you read every draft, edit it and send it yourself. Autopilot is off until you turn it on for a platform or a chat, and even then its replies wait in Pending drafts for you to edit, dismiss or send. Sending automatically is a separate per-chat switch marked Beta, which we don’t recommend. How style-matching works, and its limits, is in AI that replies to texts in your style.

The short answer

• Don’t trust a detector on something as short as a text (OpenAI withdrew its own for low accuracy), and don’t trust your gut either.
• Treat style changes as a question, not evidence.
• If it matters, ask kindly, and move to a call or a meeting.
• Worry about money requests, excuses never to meet, and pressure, not about em dashes.