Sentence spacing studies
Sentence spacing studies analyse the effects of sentence spacing techniques on the readability of text. The only direct scientific studies have been conducted by researchers from the University of Georgia, for on-screen text. There are currently no direct sentence spacing studies for printed text.
The direct studies, started in 2002, analysed single, double, and triple sentence spacing to determine what was most readable on screen. The researchers concluded that their tests did not show a statistically significant difference between the various techniques, but that further testing was needed.
Effects on readability and legibility
Claims abound regarding the legibility and readability of the single and double sentence-spacing methods—by proponents on both sides. However, typographic opinions are typically anecdotal with no basis in evidence. According to Miles Tinker, "Opinions are not always safe guides to legibility of print," and when direct studies are conducted, anecdotal opinions—even those of experts—can turn out to be false. For example, text that seems readable at first glance may be shown to impair reading effectiveness when subjected to scientific study.
Direct studies include those by Loh, Branch, Shewanown, & Ali (2002), Clinton, Branch, Holschuh, & Shewanown (2003) and Ni, Branch & Chen (2004) with results favouring neither single, double, nor triple spacing. The 2002 study indicated that "the 'double space group' consistently took longer time to finish than the 'single space' group", but the authors concluded that "there was not enough evidence to suggest that a significant difference exists". The 2003 study analysed on-screen single, double, and triple spacing. Again, the authors stated that there was insufficient evidence to draw a conclusion. A similar study was conducted in 2009 using identical spacing variables. The authors concluded that the "results provided insufficient evidence that time and comprehension differ significantly among different conditions of spacing between sentences".
There are other studies that could be relevant to sentence spacing, such as the familiarity of typographic conventions on readability. Some studies indicate that "tradition" can increase the readability of text, and that reading is disrupted when conventional printing arrangements are disrupted or violated. The standard for the Web and published books, magazines, and newspapers is single sentence spacing.
David Jury's book, What is Typography? notes the following: "Changes in spacing either between letters and words, or between the words only ... do not appear to affect legibility. [These rather extraordinary conclusions are contrary to all other surveys on readability of texts.]"
A widespread observation is that increased sentence spacing creates "rivers" or "holes" within text, making it visually unattractive, distracting, and difficult to locate the end of sentences. Comprehensive works on typography describe the negative effect on readability caused by inconsistent spacing, which is supported in a 1981 study which found that "comprehension was significantly less accurate with the river condition." Another 1981 study on Cathode Ray Tube (CRT) displays concluded that "more densely packed text is read more efficiently … than is more loosely packed text." This statement is supported in other works as well. Canadian typographer Geoffrey Dowding suggests possible explanations of this phenomenon:
A carefully composed text page appears as an orderly series of strips of black separated by horizontal channels of white space. Conversely, in a slovenly setting the tendency is for the page to appear as a grey and muddled pattern of isolated spats, this effect being caused by the over-widely separated words. The normal, easy, left-to-right movement of the eye is slowed down simply because of this separation; further, the short letters and serifs are unable to discharge an important function – that of keeping the eye on "the line". The eye also tends to be confused by a feeling of vertical emphasis, that is, an up & down movement, induced by the relative isolation of the words & consequent insistence of the ascending and descending letters. This movement is further emphasized by those "rivers" of white which are the inseparable & ugly accompaniment of all carelessly set text matter.
Some studies suggest that readability can be improved by breaking sentences into separate units of thought—or varying the internal spacing of sentences. Mid-20th century research on this topic resulted in inconclusive findings. A 1980 study split sentences into 1–5 word phrases with additional spacing between segments. The study concluded that there was no significant difference in efficacy, but that a wider study was needed. Numerous other similar studies in 1951–1991 resulted in disparate and inconclusive findings. Finally, although various studies have been conducted on the readability of proportional vs. monospaced fonts, the studies typically did not decrease sentence spacing when using proportional fonts, or did not specify whether sentence spacing was changed.
- History of sentence spacing
- Sentence spacing in language and style guides
- Sentence spacing in digital media
- Space (punctuation)
- Wheildon 1995. p. 13.
- Tinker 1963. p. 50.
- Tinker 1963. pp. 88, 108, 127, 128, 153; Wheildon 1995. pp. 8, 35.
- Tinker 1963. pp. 50, 108, 128. A useful example is the Helvetica font, an ubiquitous font that is considered extremely legible (visually pleasing in the construction and viewing of its characters), but has been found to impair reading effectiveness (readability). See Squire 2006. p. 36.
- Leonard et al. 2003.
- Loh et al., 2002. p. 4. This study used "on-screen" text in its analysis.
- Clinton 2003. The study did not find "statistically significant differences, between reading time of single and double spaces passages".
- Ni et al. 2009. pp. 383, 387, 390. This study "explored the effects of spacing after the period on on-screen reading tasks through two dependent variables, reading time and reading comprehension".
- Rhodes 1999.
- Tinker 1963. p. 124.
- Haber and Haber 1981. pp. 147–148, 152.
- Williams 2003. p. 13.
- Jury, David (2004). About Face: Reviving the Rules of Typography. Switzerland: Rotovision SA. p. 52. ISBN 2-88046-798-5. The bracketed words in the text are Jury's. For the rest of the quoted passage, Jury appears to have drawn on a report by Alison Shaw, Print for Partial Sight: A Research Report, Library Association, 1969, that he identifies on pages 51 and 247. In Jury's endnote on page 247, he points to "research done before, and at approximately the same time as, this 1969 report: G.W. Ovink, Legibility, Atmosphere-value, and Forms of Printing Types, Leiden, 1938. Donald Paterson, Miles A. Tinker, How to Make Type Readable, Harper & Brothers, 1949. Sir Cyril Birt, A Psychological Study of Typography, Cambridge University Press, 1959. Miles A. Tinker, Legibility of Print, Iowa State University Press, 1965. Miles A. Tinker, Bases for effective reading, University of Minnesota Press, 1965. Herbert Spencer, The Visible Word, Lund Humphries, 1968. The ATypl Legibility Research Committee initial report (no named author), Journal of Typographic Research, 1968."
- Dowding 1995. p. 29; Felici 2003. p. 80; Fogarty 2008. p. 85; Schriver 1997. 270; Smith 2009; Squire 2006. p. 65.
- Garner 2006. p. 83; John Wiley & Sons 2007. p. 153; Jury 2009. p. 58; Jury 2004. p. 92; Rollo 1993. p. 4; Williams 2003. p. 13.
- Craig and Scala 2006. p. 64; The Design and Publishing Center, cited in Rhodes 1999; Garzia, R.P, and R. London. Vision and Reading. (1995). Mosby Publishing, St Louis. Cited in Scales 2002. p. 4. Other studies show that "irregular and uneven spacing" disrupts the text and may slow the reader; John Wiley & Sons Australia 2007. p. 270. The context of the "irregular and uneven spacing" is concerning justified text.
- Dowding 1995. p. 5; Jury 2004. p. 92.
- Campbell, Marchetti, and Mewhort 1981. cited in Schriver 1997. p. 270.
- Kolers, Duchinsky, and Ferguson 1981.
- Dowding 1995. pp. 5–6, 29.
- Tinker 1963; North and Jenkins 1951. p. 68., cited in Tinker 1963. p. 125.
- Hartley 1980. pp. 62, 64–65, 70, 74–75. The sentences averaged 25.4 words each. Hartley does not identify which font type and sentence spacing method was used in his study. The author notes other studies, three of which found a positive correlation between segmenting parts of sentences and reading efficacy, three that noted no significance, and one that indicated a negative effect. The additional studies noted were: "Coleman and Kim, 1961; Epstein, 1967; and Murray, 1976 (with positive results); those of Nahinsky, 1956; Hartley and Burnhill, 1971; and Burnhill et al., 1975 (with non-significant results); and that of Klare et al., 1957 (a negative result)" (64).
- Bever 1991. pp. 78–80, 83–87. The text materials used in the research inserted various characters, such as pound signs in the spaces between phrases, visually interrupting the "river" effect. This study also analyzed various spacing techniques. It did not vary spacing between sentences or identify font type used, and concluded that "isolating major phrases within extra spaces facilitates reading." The article lists similar studies. The research in 14 studies in 1951–1986 correlated with the findings in the article, and six studies in 1957–1984 were inconclusive.
- Payne 1967. pp. 125–136; Black and Watts 1993.
- Black, Allison; Watts, Darren (1993). "Proofreading Monospaced and Proportionally-spaced Typefaces". Visible Language. Visible Language. 27 (3): 364–377.
- Campbell, A.J.; Marchetti, F.M.; Mewhort, D.J.K. (1981). "Reading Speed and Text Production: A Note on Right-Justification Techniques". Ergonomics. Taylor & Francis. 24 (8): 633–640. doi:10.1080/00140138108924885.
- Clinton, Gregory; Branch, Robert Maribe; Holschuh, D.; Shewanown, S. (2003). "Online Reading Performance Time as a Function of Text Layout: Roundtable Paper Presented at the 2003 AECT Leadership & Technology International Convention, Anaheim, Ca".
- Craig, James; Scala, Irene Korol (2006). Designing With Type: The Essential Guide to Typography (5th ed.). New York: Watson-Guptill. ISBN 0-8230-1413-4.
- Dowding, Geoffrey (1995). Finer Points in the Spacing & Arrangement of Type (Revised ed.). Vancouver, BC: Hartley & Marks Publishers. ISBN 0-88179-119-9.
- Felici, James (2003). The Complete Manual of Typography. Berkeley, CA: Peachpit Press. ISBN 0-321-12730-7.
- Fogarty, Mignon (2008). Grammar Girl's Quick and Dirty Tips for Better Writing. New York: Holt Paperbacks. ISBN 978-0-8050-8831-1.
- Garner, Bryan A.; Jeff Newman, Tiger Jackson (2006). The Redbook: A Manual on Legal Style (2nd ed.). Thompson West. ISBN 978-0-314-16891-7.
- Haber, Ralph Norman; Haber, Lyn R. (1981). "Visual Components of the Reading Process". Visible Language. Visible Language. 15 (2): 147–182.
- Hartley, James (1980). "Spatial Cues in Text". Visible Language. Visible Language. 14 (1): 62–79.
- Jury, David (2004). About Face: Reviving the Rules of Typography. Switzerland: Rotovision SA. ISBN 2-88046-798-5.
- Jury, David (2009). "What is Typography?" (PDF). Rotovision. pp. 28–87. Retrieved 31 March 2010.
- Kolers, Paul A.; Duchinsky, Robert; Ferguson, Dennis C. (1981). "Eye Movement Measurement of Readability of CRT Displays". Human Factors. The Human Factors Society. 23 (5): 517–527. PMID 7319497.
- Leonard, Kristi; et al. (10 October 2009). "The Effects of Computer-based Text Spacing on Reading Comprehension and Reading Rate". AECT. Retrieved 1 February 2010.
- Loh, Christian Sebastian, Robert Maribe Branch, Saun Shewanown, and Radwan Ali. Loh, Christian Sebastian, Robert Maribe Branch, Saun Shewanown, and Radwan Ali (2002). "The Effect of Text Spacing After the Period on Time for On-Screen Reading Tasks". IVLA Book of Selected Readings: Selected Readings of the IVLA Annual Conference. IVLA.
- Ni, Xiaopeng; Branch, Robert Maribe; Chen, Kuan-Chung; Clinton, Gregory (2009). Sleeman, Phillip J, ed. "The Effects of Text Spacing on Screen Reading Time and Comprehension". International Journal of Instructional Media. 36 (4).
- North, A. J.; Jenkins, L. B. (1951). "Reading Speed and Comprehension as a Function of Typography". Journal of Applied Psychology. 35 (4): 225–8. doi:10.1037/h0063094. PMID 14861125.
- Payne, Donald R. (1967). "Readability of Typewritten Material; Proportional Versus Standard Spacing". The Journal of Typographic Research. 1 (2): 125–136.
- Rhodes, John S. (13 April 1999). "One Versus Two Spaces After a Period". Webword.com. Retrieved 21 March 2010.
- Scales, Alice Y. (2002). "Improving Instructional Materials by Improving Document Formatting" (PDF). ASEE Southeast Section Conference. Retrieved 10 February 2010.
- Schriver, Karen A. (1997). Dynamics in Document Design. New York, Chichester, Brisbane, Toronto, Singapore, Weinheim: John Wiley & Sons. ISBN 0-471-30636-3.
- Squire, Victoria; Willberg, Hans Peter; Forsmann, Friedrich (2006). Getting it Right with Type. London: Laurence King Publishing. ISBN 978-1-85669-474-2.
- Smith, Laurie (8 July 2009). "Don't Date Yourself by Using Two Spaces after a Period in Your Resume!". Executive Resumes and Career Transition Strategies: Reflections of an Executive Resume Writer. Creative Keystrokes™ Executive Resume Service. Retrieved 30 March 2010.
- Tinker, Miles A. (1963). Legibility of Print. Iowa: Iowa State University Press. ISBN 0-8138-2450-8.
- Wheildon, Colin (1995). Type and Layout: How Typography and Design Can Get your Message Across – Or Get in the Way. Berkeley: Strathmoor Press. ISBN 0-9624891-5-8.
- Wiley, John, & Sons Australia (2007). Style Manual: For Authors, Editors and Printers (6th ed.). John Wiley & Sons Australia. ISBN 978-0-7016-3648-7.
- Williams, Robin (2003). The Mac is Not a Typewriter: A Style Manual for Creating Professional-level Type on Your Macintosh (2nd ed.). Berkeley, CA: Peachpit Press. ISBN 0-201-78263-4.