Readability

Readability refers to the ease with which a written text is understood by a reader, usually reported as an index such as grade level. A text with a readability of 2.0 (second-grade level) is thought to be easier to read than a text with a readability of 8.5 (corresponding to eighth grade midway through the year).

Studies of text difficulty as judged by the number of uncommon words in a text were undertaken as long ago as the 1920s. In the decades that followed, educators and psychologists developed a variety of reading formulas meant to either guide writers and editors in composing a text to fit the needs of an intended audience or organize groups of texts (text leveling) as part of an instructional scheme aimed at teaching reading. Providing guidance for the writer was the original intention of readability. The development of reading materials associated with programmed instruction constitutes the majority of recent applications of the readability concept, initially through grade-level anthologies and more recently in the process of leveling books (i.e., sorting children’s literature selections into A–Z levels).

To derive a readability score, readability formulas use measures of text features such as average number of words per sentence and average number of syllables per word. In addition, some formulas also include word frequency information drawn from a large collection of written texts. While some formulas are free, widely available, and easy to use (such as the Fry Readability Graph), others (such as the Lexile score formula) are proprietary and require payment for use.

Critics of text readability note that the original intent was to aid writers rather than to focus on the reader’s experience. There are also concerns about the validity and reliability of readability formulas. Because different formulas register unacceptable disparities when applied to the same text, readability suffers from concerns about concurrent validity. For example, calculations of the range of readability scores of eight different available formulas showed that scores varied as widely as fifth-grade levels on picture book texts typically used in first or second grade and sixth-grade levels on picture books suited to middle school readers. In addition, discrepancies in readability measures when excerpts are scored in different places within the same text have raised questions about the reliability of readability as a construct.

The concept of readability is seated in a word-oriented theory of reading that is ultimately nonproductive because it fails to account for the wide variety of reader behaviors during uninterrupted [Page 1561]readings of authentic texts. Sociopsycholinguistic studies have shown that reading involves a dynamic transaction between a reader and a text, situated in a social context, and comprehension involves interpretation or active meaning construction. From this perspective, any reading transaction involves factors related to readers (such as purpose, knowledge, motivation, experiences, and interests) and factors related to social context (e.g., physical and social environment, nature of task) as well as text-related factors.