Entity Density

A discourse-level readability feature measuring how many distinct entities — named entities (people, places, organisations) and general nouns — a text introduces per sentence or document. High entity density increases working-memory load on readers because each new entity must be tracked and integrated with prior context. Entity density is particularly relevant to cognitive accessibility: it is one of the strongest single predictors of text difficulty for readers with intellectual disabilities and was introduced in accessibility-motivated readability research by Feng, Elhadad, and Huenerfauth.