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Automated Readability Scoring(also: ARSS, Automated Readability Scoring System, Readability Assessment)

The use of computational methods to automatically evaluate the reading difficulty level of a text. Traditional readability formulas like Flesch-Kincaid and Dale-Chall use surface features such as average sentence length, word length, and vocabulary frequency to assign…

Automatic Readability Assessment(also: Readability Prediction, Reading Level Assessment)

The computational task of predicting how difficult a text is for a reader, usually expressed as a grade level or a readability score. Modern systems treat readability as a machine-learning classification or regression problem that combines shallow surface features (sentence…

Coh-Metrix

A web-based tool developed at the University of Memphis that analyses text on more than a hundred measures of language, cohesion, and readability, including referential and semantic cohesion, lexical diversity, syntactic complexity, and latent semantic analysis. Coh-Metrix moves…

Dale-Chall Readability Formula(also: Dale-Chall, New Dale-Chall)

A readability formula first published by Edgar Dale and Jeanne Chall in 1948 and revised in 1995. Unlike formulas that rely only on surface counts, Dale-Chall compares every word in a text against a manually curated list of "easy" words familiar to fourth-grade readers; the raw…

Easy Read(also: Easy-to-Read, Easy Language, Plain Language for Cognitive Accessibility)

A method of presenting written information in a way that is accessible to people with intellectual disabilities, learning difficulties, or low literacy. Easy Read uses short sentences, common everyday vocabulary, active voice, and clear structure, often accompanied by images or…

Entity Density(also: Entity-Density Features)

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…

Entity Grid(also: Entity-Grid Model)

A model of local text coherence proposed by Barzilay and Lapata (2008) that represents a document as a two-dimensional grid: rows are sentences, columns are salient entities, and each cell records the grammatical role of that entity in that sentence (subject, object, other, or…

Fixation Duration(also: Fixation Time, Gaze Duration)

The length of time the eye remains relatively still on a specific point in a visual display during reading or visual processing. In eye-tracking research, fixation duration is a key metric for measuring cognitive processing load and readability — shorter fixations are associated…

Flesch Reading Ease(also: Flesch Readability Score, Flesch Score, FRE)

A readability formula developed by Rudolf Flesch in 1948 that rates text on a 100-point scale based on average sentence length and average number of syllables per word. Higher scores indicate easier-to-read text: scores of 60-70 are considered suitable for a general audience,…

Flesch-Kincaid Grade Level(also: Flesch-Kincaid, FKGL, Flesch-Kincaid readability)

A readability formula that estimates the U.S. school grade level required to comfortably read a given English text, based on average sentence length and average syllables per word. Developed for the U.S. Navy in 1975 by Rudolf Flesch and J. Peter Kincaid, the formula is widely…

Fluency(also: Text fluency, Grammatical fluency)

In natural language processing and text simplification, fluency is the degree to which a piece of text is grammatically correct and reads naturally in the target language. It is one of three standard evaluation dimensions for automatic text simplification alongside complexity…

Gunning Fog Index(also: Gunning FOG, FOG Index)

A traditional readability formula developed by Robert Gunning in 1952 that estimates the years of formal education a reader needs to understand a text on first reading. It is calculated from average sentence length plus the percentage of "complex" words — words with three or…

Italic Font Style(also: italics, oblique)

A slanted or cursive-style variant of a typeface, traditionally used for emphasis, titles, or foreign words. Eye-tracking research demonstrates that italic fonts create significant accessibility barriers—Arial Italic, for example, showed the worst reading performance across…

Jenga Format

Jenga format is a content transformation technique designed to enhance web page readability for non-native English readers. Developed by Chen-Hsiang Yu and Robert C. Miller at MIT, it restructures text presentation by visually grouping syntactic units within sentences, making…

Lexical Chain(also: Lexical Chaining, Lexical Cohesion)

A sequence of semantically related words running through a text — for example, "doctor", "hospital", "nurse", "patient" — connected by relations like synonymy, hypernymy, or hyponymy. Lexical chains capture the topical coherence of a document and are used in readability…

Lexile Framework(also: Lexile, Lexile Measure)

A commercial readability framework developed by MetaMetrics that places both texts and readers on a common scale — the Lexile measure — to support matching readers with materials at an appropriate level of challenge. A text's Lexile measure is computed from sentence length and…

Lexile Score(also: Lexile Measure, Lexile Level)

A standardised measure of text complexity and reading ability, expressed on the Lexile scale (roughly 0L to 1600L+). A Lexile text measure reflects sentence length and word frequency; a Lexile reader measure reflects the reader's ability. For accessibility, Lexile scores provide…

Monospaced Font(also: fixed-width font, fixed-pitch font, non-proportional font)

A typeface in which every character occupies the same horizontal space, regardless of its width. Examples include Courier, Consolas, and Monaco. Research shows monospaced fonts like Courier lead to shorter fixation durations for people with dyslexia, making them a strong choice…

Newsela

An educational content platform that publishes news articles in multiple professionally-edited versions simplified to different U.S. school reading levels, enabling teachers to assign the same story at grade-appropriate difficulty. Because Newsela pairs original articles with…

Plain Language(also: Plain English, Clear Language, Simple Language)

Plain language is communication that is clear, concise, and well-organized so that the intended audience can easily find, understand, and use the information. In accessibility, plain language is essential for making content accessible to people with cognitive disabilities, low…

Proportional Font(also: variable-width font)

A typeface in which characters have varying widths based on their natural proportions—a narrow "i" takes less space than a wide "m". Most fonts used in everyday reading are proportional, including Arial, Times New Roman, and Verdana. While proportional fonts create a more…

Readability formula(also: readability metric, readability index, readability measure)

A mathematical formula that estimates the difficulty of reading a text, typically based on features like sentence length, word length, syllable count, or vocabulary frequency. Common formulas include Flesch Reading Ease, Flesch-Kincaid Grade Level, SMOG, and Gunning Fog Index.…

Reading Fluency

The ability to read connected text accurately, at an appropriate pace, and with proper expression - distinct from word-level decoding skill on one side and from reading comprehension on the other. Fluency is typically measured along three dimensions: accuracy (proportion of…

Reading Level(also: Grade Level, Reading Grade Level)

An estimate of the education or skill level a reader needs to understand a text, usually expressed as a U.S. school grade (e.g., grade 4) or an equivalent band. Reading level is the target output of most readability formulas and automatic readability assessment systems, and it…

SMOG(also: SMOG Index, SMOG Grade, Simple Measure of Gobbledygook)

A readability formula developed by G. Harry McLaughlin in 1969 that estimates the years of education needed to understand a text, based on the number of polysyllabic words (three or more syllables) in a fixed sample of sentences. SMOG is widely used in healthcare communication…

Sans-Serif Font(also: sans serif, grotesque font)

A typeface that lacks the small projecting lines (serifs) at the ends of letter strokes. Sans-serif fonts like Arial, Helvetica, and Verdana are generally recommended for screen readability and are often preferred for users with dyslexia. Research shows sans-serif fonts lead to…

Serif Font(also: roman typeface)

A typeface with small decorative lines or strokes (serifs) at the ends of letter strokes. Common serif fonts include Times New Roman, Garamond, and Georgia. While traditionally associated with print legibility, serif fonts have shown mixed results for screen readability.…

Speed-Comprehension Trade-off(also: Speed-Accuracy Trade-off in Reading)

An empirical pattern in readability research: typographic, layout, and presentation choices that increase reading speed often reduce comprehension accuracy, and vice versa. For example, sans-serif faces and shorter line lengths tend to support faster reading but may yield lower…

Text Complexity(also: Linguistic complexity, Text difficulty)

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…

Typeface Classification(also: Font Classification, Typeface Categories)

The set of broad categories used to describe and compare typefaces. The most common groupings are: serif (letters with small projecting strokes at terminals, e.g. Times, Roboto Serif), sans-serif (no terminal strokes, e.g. Helvetica, Arial, Roboto), slab serif (heavy…

Visual-Syntactic Text Formatting(also: VSTF)

Visual-Syntactic Text Formatting (VSTF) is a content presentation method that formats text based on its syntactic structure, using indentation, line breaks, and visual grouping to align with the grammatical structure of sentences. Research has shown VSTF can improve online…

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