Readability is the ease with which a reader can understand a written text. The concept exists in both natural language and programming languages, though in different forms. In natural language, the readability of text depends on its content (the complexity of its vocabulary and syntax) and its presentation (such as typographic aspects that affect legibility, like font size, line height, character spacing, and line length). In programming, things such as programmer comments, choice of loop structure, and choice of names can determine the ease with which humans can read computer program code.
Higher readability in a text eases reading effort and speed for the general population of readers. For those who do not have high reading comprehension, readability is necessary for understanding and applying a given text. Techniques to simplify readability are essential to communicate a set of information to the intended audience.
Definition The term "readability" is inherently broad and can become confusing when examining all of the possible definitions.Dale, Edgar and Jeanne S. Chall. 1949. "The concept of readability." Elementary English 26:23. Readability is a concept that involves audience, content, quality, legibility, and can even involve the formatting and design structure of any given text.Harris, Theodore L. and Richard E. Hodges, eds. 1995. The Literacy Dictionary, The Vocabulary of Reading and Writing. Newark, DE: International Reading Assn. Different definitions of readability exist from various sources. The definition fluctuates based on the type of audience to whom one is presenting a certain type of content. For example, a technical writer might focus on clear and concise language and formatting that allows easy-reading. In contrast, a scholarly journal would use sophisticated writing that would appeal and make sense to the type of audience to whom they are directing information.
Applications Readability is essential to the clarity and accessibility of texts used in classrooms, work environments, and everyday life.
Much research has focused on matching prose to reading skill, resulting in formulas for use in research, government, teaching, publishing, the military, medicine, and business.Fry, E. B. 1986. Varied uses of readability measurement. Paper presented at the 31st Annual Meeting of the International Reading Association, Philadelphia, PA. Readability measurement in non-English languages has also been the focus of various studies.Rabin, A. T. 1988 "Determining difficulty levels of text written in languages other than English." In Readability: Its past, present, and future, eds. B. L. Zakaluk and S. J. Samuels. Newark, DE: International Reading Association.Antunes, H., Lopes, C.T. (2019). Analyzing the Adequacy of Readability Indicators to a Non-English Language. In: Crestani, F., et al. Experimental IR Meets Multilinguality, Multimodality, and Interaction. CLEF 2019. Lecture Notes in Computer Science, vol 11696. Springer, Cham. url=https://doi.org/10.1007/978-3-030-28577-7_10
The two publications with the largest circulations, TV Guide (13 million) and Reader's Digest (12 million), are written at the 9th-grade level. The most popular novels are written at the 7th-grade level. This supports the fact that the average adult reads at the 9th-grade level. It also shows that, for recreation, people read texts that are two grades below their actual reading level.
History
Early research For centuries, teachers and educators have seen the importance of organization, coherence, and emphasis in good writing. In the 1880s, English professor L. A. Sherman found that the English sentence was getting shorter. In Elizabethan times, the average sentence was 50 words long while in Sherman's modern time, it was 23 words long.Sherman, Lucius Adelno 1893. Analytics of literature: A manual for the objective study of English prose and poetry. Boston: Ginn and Co.
In 1889 in Russia, the writer Nikolai A. Rubakin published a study of over 10,000 texts written by everyday people. From these texts, he took 1,500 words he thought most people understood. He found that the main blocks to comprehension are unfamiliar words and long sentences.Lorge, I. 1944. "Word lists as background for communication." Teachers College Record 45:543–552. Starting with his own journal at the age of 13, Rubakin published many articles and books on science and many subjects for the great numbers of new readers throughout Russia. In Rubakin's view, the people were not fools. They were simply poor and in need of cheap books, written at a level they could grasp.
Reading ease
The earliest reading ease assessment is the subjective judgment termed text leveling. Formulas do not fully address the various content, purpose, design, visual input, and organization of a text.Clay, M. 1991. Becoming literate: The construction of inner control. Portsmouth, NH: Heinneman.Fry, E. B. 2002. "Text readability versus leveling." Reading Teacher 56 no. 23:286–292. Text leveling is commonly used to rank the reading ease of texts in areas where reading difficulties are easy to identify, such as books for young children. At higher levels, ranking reading ease becomes more difficult, as individual difficulties become harder to identify. This has led to better ways to assess reading ease.
In the 1920s, the scientific movement in education looked for tests to measure students' achievement to aid in curriculum development. Teachers and educators had long known that, to improve reading skill, readers—especially beginning readers—need reading material that closely matches their ability. University-based psychologists did much of the early research, which was later taken up by textbook publishers.Fry, Edward B. 2006. "Readability." Reading Hall of Fame Book. Newark, DE: International Reading Assn. In 1921, Harry D. Kitson published The Mind of the Buyer, one of the first books to apply psychology to marketing. Kitson's work showed that each type of reader bought and read their own type of text. On reading two newspapers and two magazines, he found that short sentence length and short word length were the best contributors to reading ease.Kitson, Harry D. 1921. The Mind of the Buyer. New York: Macmillan.
In 1923, Bertha A. Lively and Sidney L. Pressey published the first reading ease formula. They were concerned that junior high school science textbooks had so many technical words and that teachers would spend all class time explaining these words. They argued that their formula would help to measure and reduce the "vocabulary burden" of textbooks. Their formula used five variable inputs and six constants. For each thousand words, it counted the number of unique words, the number of words not on the Thorndike list, and the median index number of the words found on the list. Manually, it took three hours to apply the formula to a book.Lively, Bertha A. and S. L. Pressey. 1923. "A method for measuring the 'vocabulary burden' of textbooks. Educational administration and supervision 9:389–398.
After the Lively–Pressey study, people looked for formulas that were more accurate and easier to apply. In 1928, Carleton Washburne and Mabel Vogel created the first modern readability formula. They validated it by using an outside criterion, and correlated .845 with test scores of students who read and liked the criterion books.The Classic Readability Studies, William H. DuBay, Editor (chapter on Washburne, C. i M. Vogel. 1928). It was also the first to introduce the variable of interest to the concept of readability.Washburne, C. and M. Vogel. 1928. "An objective method of determining grade placement of children's reading material. Elementary school journal 28:373–81.
Between 1929 and 1939, Alfred Lewerenz of the Los Angeles School District published several new formulas.Lewerenz, A. S. 1929. "Measurement of the difficulty of reading materials." Los Angeles educational research bulletin 8:11–16.Lewerenz, A. S. 1929. "Objective measurement of diverse types of reading material. Los Angeles educational research bulletin 9:8–11.Lewerenz, A. S. 1930. "Vocabulary grade placement of typical newspaper content." Los Angeles educational research bulletin 10:4–6.Lewerenz, A. S. 1935. "A vocabulary grade placement formula." Journal of experimental education 3: 236Lewerenz, A. S. 1939. "Selection of reading materials by pupil ability and interest." Elementary English review 16:151–156.
In 1934, educational psychologist Edward Thorndike of Columbia University noted that, in Russia and Germany, teachers used word frequency counts to match books to students. Word skill was the best sign of intellectual development, and the strongest predictor of reading ease. In 1921, Thorndike published Teachers Word Book, which contained the frequencies of 10,000 words.Thorndike E.L. 1921 The teacher's word book. 1932 A teacher's word book of the twenty thousand words found most frequently and widely in general reading for children and young people. 1944 (with J.E. Lorge) The teacher's word book of 30,000 words. He also published his readability formula. He wrote that word skills can be increased if the teacher introduces new words and repeats them often.Thorndike, E. 1934. "Improving the ability to read." Teachers college record 36:1–19, 123–44, 229–41. October, November, December. In 1939, W.W. Patty and W. I Painter published a formula for measuring the vocabulary burden of textbooks. This was the last of the early formulas that used the Thorndike vocabulary-frequency list.Patty. W. W. and W. I. Painter. 1931. "A technique for measuring the vocabulary burden of textbooks." Journal of educational research 24:127–134. Until computers came along, word frequency lists were the best aids for grading reading ease of texts.Klare, G. R. and B. Buck. 1954. Know Your Reader: The scientific approach to readability. New York: Heritage House.
In 1981 the World Book Encyclopedia listed the grade levels of 44,000 words.Dale, E. and J. O'Rourke. 1981. The living word vocabulary: A national vocabulary inventory. World Book-Childcraft International. A popular strategy amongst educators in modern times is "incidental vocabulary learning," which enforces efficiency in learning vocabulary in the short-term rather than drilling words and meanings teachers hope will stick. The incidental learning tactic is meant to help learners build comprehension and learning skills rather than memorizing words. Through this strategy, students would hopefully be able to navigate various levels of readability using context clues and comprehension.
Readability studies
During the Great Depression of the 1930s, the U.S. government invested in adult education. In 1931, Douglas Waples and Ralph Tyler published What Adults Want to Read About. It was a two-year study of adult reading interests. Their book showed not only what people read but what they would like to read. They found that many readers lacked suitable reading materials: they would have liked to learn but the reading materials were too hard for them.Waples, D. and R. Tyler. 1931. What adults want to read about.Chicago: University of Chicago Press.
Lyman Bryson of Teachers College, Columbia University found that many adults had poor reading ability due to poor education. Even though colleges had long tried to teach how to write in a clear and readable style, Bryson found that it was rare. He wrote that such language is the result of a "...discipline and artistry that few people who have ideas will take the trouble to achieve... If simple language were easy, many of our problems would have been solved long ago." Bryson helped set up the Readability Laboratory at the college. Two of his students were Irving Lorge and Rudolf Flesch.