Text Complexity

The degree to which a piece of writing demands advanced reading skills to comprehend, driven by factors such as vocabulary frequency, syntactic structure, sentence length, passage organisation, and background-knowledge assumptions. In Automatic Text Simplification and reading-assistance research, complexity is one of three standard evaluation dimensions alongside fluency (grammaticality) and faithfulness (meaning preservation). Complexity is typically measured via objective proxies such as Flesch-Kincaid grade level, reading speed, or comprehension questions, or via subjective Likert judgements of readability and understandability from the target reader group. Researchers working with disabled users including DHH adults, people with dyslexia, and people with aphasia have found that different metrics distinguish complexity levels with different reliability depending on the reader’s literacy level.