HumanSounding

The AI Vernacular Index: a live reference for the words, phrases, and habits that mark text as model-written. Check your own draft, see what each model does and how often, what's measurably rising or falling, and download an instruction file that steers any model away from the worst of it.

Last updated August 10, 2026 Refreshed weekly from published studies and detector data

Check your draft

Paste anything you're about to send. The highlights show every recognizable AI tell, with a plainer fix for each. Your text never leaves this page — the check runs entirely in your browser, and only anonymous counts of which tells fired are recorded, never the text.

~6%
of sampled ChatGPT messages contained a "not just X, but Y" variant
Washington Post analysis of 328,744 messages, July 2025
13.5%
of 2024 biomedical abstracts show LLM-assisted wording (40% in some subfields)
Kobak et al., Science Advances 2025
3.3×
GPT-4.1's em-dash rate vs. the human baseline (10.6 vs 3.2 per 1,000 words)
SlopDetector corpus measurement, 2026
97.1%
accuracy telling ChatGPT, Claude, Gemini, Grok and DeepSeek apart by style alone
Sun et al. (CMU), "Idiosyncrasies in LLMs"

The numbers behind the tells

Left: phrases measured against human writing by GPTZero across millions of documents. Right: em-dash density by model, against a measured human baseline. Hover any bar for the source.

Phrase overuse vs. human text

How many times more often the phrase appears in AI text · GPTZero, Oct 2024

Em dashes per 1,000 words

Model defaults vs. human essay baseline · SlopDetector, 2026

human baseline · model output

Each model's accent

Most "AI-isms" are shared across every model. But each one has habits distinct enough that a classifier can name the author. Confidence labels: measured = quantitative study · documented = widely reported, official acknowledgment, or dedicated tracking · anecdotal = community consensus without hard counts.

ChatGPT (OpenAI)

  • "It's not just X, it's Y." Negative parallelism, in ~6% of sampled real messages. measured
  • Em dashes as a brand. Highest measured rate of the big models; Altman announced a fix in Nov 2025 that made custom instructions work, but defaults barely moved until GPT-5.4. measured
  • The "delve" era vocabulary. Delve, tapestry, underscore, showcase — the 2023–24 tells, now fading from new output while still spreading through human speech. Watch instead for "core" and "modern". measured
  • Markdown maximalism. Heaviest user of bold text, headers, and "Bold term: explanation" bullets. measured
  • Sycophancy spike. The April 2025 GPT-4o update was rolled back within a week for being "overly flattering"; GPT-5 then overcorrected cold and was warmed back up. documented

Claude (Anthropic)

  • "You're absolutely right!" The signature. Official GitHub bug #3382, a dedicated tracker site (absolutelyright.lol), and self-parody from Anthropic's own account. documented
  • Affirmation, then reversal. The praise often signals a correction or backpedal is coming next. documented
  • The apology cascade. "Ah, I see the issue now" → "You're absolutely right" → "Apologies for the confusion", on loop in coding sessions. anecdotal
  • Prompt-referencing. Leans on "based on the text", "according to the passage" — a phrase family classifiers use to identify it. measured
  • Counter-tell: uses less bold and fewer headers than ChatGPT. The "wall of markdown" is a ChatGPT accent that gets misattributed to Claude. measured

Gemini (Google)

  • Most agreeable model measured. 62.5% sycophantic response rate in Stanford's SycEval, ahead of ChatGPT-4o's 56.7%. measured
  • Plain-vocabulary preference. Says "sugar" where ChatGPT says "glucose" — stylometric analysis attributes text to it by exactly this friendliness. measured
  • The self-loathing loop. "I am a disgrace to my profession… to this planet" — a 2025 failure-mode bug Google acknowledged, unique to Gemini. documented
  • Fewest em dashes of the majors — 3.5 per 1,000 words, close to the human rate. measured
  • Phrase-level tells are thin. Its fingerprint is statistical (word distributions, register) more than catchphrases — but strong enough that DeepSeek R1's training data was traced to Gemini output by style alone. documented

Read the difference

The same content written twice. Hover the highlights to see which tell each one is.

In the vernacular

In today's fast-paced digital landscape, WidgetFlow isn't just another project tool — it's a paradigm shift. Our platform seamlessly leverages cutting-edge AI to streamline your workflow, empowering teams to unlock their full potential. From scrappy startups to global enterprises, WidgetFlow boasts a robust suite of features designed to foster collaboration, enhance productivity, and elevate performance. It's important to note that every feature was meticulously crafted with the user in mind. The result? A truly transformative experience that stands as a testament to what's possible. In conclusion, WidgetFlow represents more than a tool — it's a comprehensive ecosystem for the modern workplace.

Without it

WidgetFlow is a project tracker for teams that have outgrown spreadsheets. It schedules work, flags conflicts before they block anyone, and writes the weekly status report for you. Setup takes about ten minutes.

The scheduling engine is the part we're proudest of. It plans from your team's actual pace over the last six sprints, not from estimates, so the plan stops being fiction by Wednesday.

Free for 30 days. If it doesn't save you an hour in the first week, cancel from the billing page in two clicks.

In the vernacular

The Q2 results underscore the pivotal role of our multifaceted growth strategy. Revenue saw significant improvements, highlighting the team's meticulous execution and unwavering commitment to excellence. While challenges remain, the overall trajectory serves as a testament to our resilience. Moving forward, we will continue to leverage synergies across the organization — ensuring sustainable, long-term value creation for all stakeholders.

Without it

Q2 revenue came in at $4.2M, up 18% on Q1. Most of the gain came from the enterprise tier, which closed 11 accounts against a target of 8.

Churn is the sore spot. We lost two mid-market customers over pricing and don't yet have a fix; Dana's team owes a proposal by August 22.

The Q3 plan bets on the enterprise pipeline holding. If it slips, the events budget gets cut first.

What changed in each rewrite: specific numbers replace abstractions, sentence lengths vary, no triplets, one em dash total across both, and each ends on new information instead of a summary.

Make your AI stop doing this

Two files, same rules, different packaging. Both are built from the evidence above and prioritize the loudest tells first.

Claude skill file

A SKILL.md for Claude's skill system. Claude applies it automatically whenever it drafts prose for you.

How to use
Claude.ai: Settings → Capabilities → Skills → upload. Claude Code / Cowork: drop the file in a write-like-a-person/ folder under ~/.claude/skills/, or ask Claude to save it as a skill.

Portable instructions (any model)

Plain text that fits in a custom-instructions box. Works in ChatGPT, Gemini, Claude, or pasted at the top of any prompt.

ChatGPT
Settings → Personalization → Custom instructions → "How would you like ChatGPT to respond?"
Gemini
Settings → Saved info, or paste into a Gem's instructions.
Claude
Project instructions, or Settings → Profile → personal preferences.

Method and honesty notes

Three caveats worth keeping in view. First, attribution is hard: most "Claude-isms" and "Gemini-isms" people complain about are generic LLM habits attributed to whichever model the complainer uses most; this page marks per-model claims with confidence labels for that reason. Second, the tells are a moving target: labs tune out each meme (delve, em dashes, markdown walls) roughly a year after it peaks, so the durable signals are structural — cadence, negative parallelism, triplets — not word lists. Third, avoiding the vernacular makes text less annoying to readers, but it does not defeat detectors: stylometric classifiers still identify model output at 90%+ accuracy after paraphrasing. Nothing here is for passing text off where AI disclosure is required.

Sources

Kobak et al., "Delving into LLM-assisted writing in biomedical publications" (Science Advances 2025) — excess-vocabulary method; 13.5% figure; delve 28×.

Juzek & Ward, "Why Does ChatGPT 'Delve' So Much?" (COLING 2025) — 21 focal words; +6,697% "delves".

Liang et al., "Monitoring AI-Modified Content at Scale" (ICML 2024) — peer-review word spikes; 6.5–16.9% modified reviews.

Liang et al., Nature Human Behaviour 2025 — LLM share of scientific papers by field.

Yakura et al. (Max Planck), LLM influence on human spoken communication — 737k hours of podcasts; "delve" in speech.

Juzek, Anderson & Galpin (FSU, AIES 2025) — AI words in unscripted speech.

Sun et al. (CMU), "Idiosyncrasies in Large Language Models" — 97.1% five-way model identification; per-model markers.

GPTZero, most common AI vocabulary — phrase multipliers (182×, 120×, 107×…).

SlopDetector, em-dash density data (2026) — per-model em-dash rates vs human baseline.

"The Last Fingerprint: How Markdown Training Shapes LLM Prose" (2026) — suppression-resistance; GPT-5.4 changes.

Wikipedia: Signs of AI writing (WP:AISIGNS) — the editor-built taxonomy this page's structural categories follow.

Decrypt, "The 5 Biggest Tells" (Nov 2025) — Washington Post 328,744-message dataset; "not just" ~6%.

TechCrunch, OpenAI's em-dash fix (Nov 2025) — and PCWorld's caveats.

OpenAI, "Sycophancy in GPT-4o" (Apr 2025) — the rollback postmortem.

anthropics/claude-code#3382 — the "You're absolutely right!" bug report; tracker at absolutelyright.lol.

SycEval (Stanford) coverage — sycophancy rates: Gemini 62.47%, ChatGPT-4o 56.71%.

Scientific American / Rudnicka — ChatGPT vs Gemini stylometry ("glucose" vs "sugar").

Forbes, Gemini's self-loathing loop (Aug 2025).

Breunig, slop forensics & model ancestry — with sam-paech/slop-forensics and EQ-Bench Slop Score.

Scientometrics 2026 multi-database study — "underscore" through July 2025.

Built from published studies, detector datasets, and editor guides; per-item confidence is labeled where attribution is uncertain. Figures are quoted from their sources without adjustment; corpora, dates, and definitions differ between studies, so multipliers are not directly comparable across charts. Privacy: the draft checker runs entirely in your browser and your text is never transmitted; the site records only anonymous daily counts (visits, which tells fired, referrer domain) with no IPs, cookies, or personal data. Maintained by Gregg with Claude. Not affiliated with OpenAI, Anthropic, or Google.