graphic of picture of George Klare
Fig. 8. George Klare. After serving as a navigator for the U.S. Air Force in WWII (in which he was shot down and captured by the Germans), Klare became a leading figure in readability research.
  • Know Your Reader: The Scientific Approach to Readability, which he wrote with Byron Buck (1954).
  • The Measurement of Readability (1963).
  • "Assessing Readability" in the Reading Research Quarterly (1974-75). The Institute for Scientific Information recognized it as a Citation Classic, one of the scientific works most frequently cited in other studies - with well over 125 citations so far.
  • "A Second Look at the Validity of the Readability Formulas" in The Journal of Reading Behavior (1976).
  • "Readable Technical Writing: Some Observations" in Technical Communication (1977), which won "Best of Show" in the International Conference of the STC in Dallas in 1978.
  • A Manual for Readable Writing (1975).
  • How to Write Readable English (1980).
  • "Readability" in Encyclopedia of Educational Research (1982).
  • "Readability" in The Handbook of Reading Research (1984).
  • "Readable Computer Documentation" in the ACM Journal of Computer Documentation (2000), which covered the latest research in readability.

Critics of the formulas (e.g., Redish and Selzer 1985) have complained that the readability formulas were developed for children and they never were never formulated or tested with technical documents. The record shows, however, that popular formulas such as the Flesch Reading Ease and the Kincaid formulas were developed mainly for adults and have been tested extensively on adult materials. For example, Klare (1952) tested the Lorge, Flesch Reading Ease, and Dale-Chall formulas against the 16 standardized passages of the Ojemann tests (1934) and the 48 passages of Gray and Leary (1935) tests, all developed for adult readers.

As we will see, several extensive studies (Klare et al. 1955a, Klare et al. 1957, Klare and Smart 1973, Caylor et al. 1973, Kincaid et al. 1975, Hooke et al. 1979) used materials developed for technical training and regulations in the military to formulate and test several of today's most popular formulas such as the Flesch-Kincaid grade-level formula.

Perhaps Klare's most important studies were those confirming the effects of prior knowledge, reading ability, interest, and motivation on adult reading (See below).

The cloze test

Wilson Taylor (1953) of the University of Illinois published "Cloze Procedure: A New Tool for Measuring Readability." Taylor cited several difficulties with the classic readability formulas such as the Flesch and Dale-Chall. He noted, for instance, that Gertrude Stein's works measured much easier on the readability scales than expected.

Taylor argued that words are not the best measure of difficulty but how they relate to one another. He proposed using deletion tests called cloze tests for measuring an individual's understanding of a text. Cloze testing is based on the theory that readers are better able to fill in the missing words as their reading skills improve.