Perplexity
Definition
A measure of how surprising a sequence of words is to a language model. LLMs tend to generate low-perplexity text (predictable word choices); human writing often shows higher and more variable perplexity. Detection tools exploit this, but the distinction breaks down with formal academic prose.
Related terms
- AI detection classifier
- A machine-learning system trained to discriminate between human-written and LLM-generated text by measuring features such as perplexity, burstiness, and n-gram probabilities. Current...
- Burstiness
- The variance in sentence-level complexity across a passage. Human writing tends to mix complex and simple sentences unevenly; LLM output tends to...
- Human-LLM collaboration
- Text production in which a human contributes prompts, editing decisions, and intentional content while an LLM generates or transforms the prose. The...
- Large language model (LLM)
- A neural network trained on large text corpora to predict likely next tokens. At inference, it generates text by sampling from probability...
- Stylometric signature
- The set of measurable linguistic features : function-word frequencies, sentence length, punctuation patterns, vocabulary richness : that characterises a specific writer's output...
Explained in
- AI-Generated Text: Authorship, Detection, and the New Evidential FrontierA measure of how surprising a sequence of words is to a language model. LLMs tend to generate low-perplexity text (predictable word choices); human writing oft...