Most AI detectors focus on word choice and sentence patterns. An arXiv preprint introduces a different approach: IdeaLens tries to estimate whether a document’s underlying ideas came from a human or an AI, even when someone else wrote the prose.
Researchers from the University of Maryland, Google DeepMind and Simon Fraser University built the system to separate what a document says from how it says it.
How IdeaLens works
IdeaLens converts each document into an outline. Every outline item pairs a discourse role, such as an event or evaluation, with a short description of the content. The outlines are then paraphrased to reduce overlap with the original wording.
The team trained IdeaLens on 1 million documents from FineWeb. Its training labels came from Pangram, an existing prose detector. A control model called ProseLens used the same documents and labels but analyzed the original text instead of outlines.
What the tests found
In the researchers’ IdeaShift benchmark, IdeaLens’s AI flag rate fell from about 95% to 7% as AI-generated documents incorporated increasingly detailed human plans. Pangram 4 still flagged about 92% of documents generated from full human outlines. When the plans came from AI instead, IdeaLens’s flag rate stayed above 96%.