Key points
- Low perplexity + low burstiness = the classic 'AI' statistical fingerprint.
- Human writing naturally bursts between short punchy sentences and long complex ones.
- Humanizer tools work specifically by increasing both metrics through restructuring.
These two metrics are the foundation of nearly every AI detector on the market. Perplexity measures how surprising or predictable each word choice is; burstiness measures how much sentence length and structure vary across a passage.
What this means for you
Low perplexity + low burstiness = the classic 'AI' statistical fingerprint. Understanding this distinction is the foundation for evaluating any specific tool's marketing claims — see our full humanizer comparison table for how individual tools stack up.
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