Reading Onscreen: The Effects of Line Length on Performance
by Dr. Bob Bailey
Do most of the primary users of your Web site prefer to read the information onscreen, or do they usually "print then read"? Second, if they prefer to read onscreen, how long should the line lengths be?
For over 125 years, one active area of usability investigation has been the influence of line length on the speed of reading prose text. Weber (1881) made the first research-based recommendations when he suggested that an ideal line length was four inches (Bailey, 2002). Almost 50 years later, Tinker and Paterson (1929) reported that line lengths between three inches and three and a half inches were ideal.
As computer monitors became more prevalent in "line-length" studies, longer line lengths seemed to enable faster reading performance. One of the first studies with computer monitors (Duchnicky and Kolers, 1983) found that longer text widths resulted in 28 percent faster reading times over narrower text widths. Other studies (cf. Dyson and Kipping, 1998; Youngman and Scharff, 1999) continued to show that reading rates increased as characters per line increased. These same studies have reliably shown that users prefer shorter line lengths (about four inches).
Reading from a Monitor
The opportunities for reading onscreen text are steadily increasing. In a 2004 survey by Shaikh and Chaparro (2004), they reported that users preferred to read longer articles, such as technical reports and journal articles in printed form; other documents, however, such as online news, newsletters, and product reviews were preferred in onscreen formats.
The Most Recent Study
Dawn Shaikh (2005) reported a study that examined the effects of line length on reading speed, comprehension, and user satisfaction when reading online news articles. She had 20 college-aged students read news articles displayed in 35, 55, 75, or 95 characters per line on a computer monitor This is equivalent to line lengths of four, six, eight and 10 inches on a 1024x768 pixel resolution monitor using the Arial font. Her results showed that passages formatted in the longest line length (95 characters per line or 10 inches) resulted in the fastest reading speed. The participants reported no reliable line length preferences.
The best available research suggests that users will read fastest if the line lengths are longer (up to 10 inches). If the line lengths are too short (e.g., two and a half inch columns), the line length probably will impede rapid reading. Users tend to prefer lines that are relatively short (about four inches).
Bailey, R.W. (2002). Optimal line length: Research supporting how line length affects usability, December, www.webusability.com/article_line_length_12_2002.htm.
Duchnicky, J.L. and Kolers, P.A. (1983). Readability of text scrolled on visual display terminals as a function of window size, Human Factors, 25, 683-692.
Dyson, M.C. and Kipping, G.J. (1998). The effects of line length and method of movement on patterns of reading from screen, Visible Language, 32, 150-181.
Shaikh, A.D. (2005),. The effects of line length on reading online news, Usability News, 7.2, downloaded April 15, 2006 - http://psychology.wichita.edu/surl/usabilitynews/72/LineLength.htm
Shaikh, A. D. and Chaparro, B. S. (2004). A survey of online reading habits of Internet users. Proceedings of the Human Factors and Ergonomics Society 48th Annual Meeting, 875-879.
Tinker, M.A. and Paterson, D.G. (1929). Studies of typographical factors influencing speed of reading: Length of line, The Journal of Applied Psychology, 13(3), 205-219.
Weber, A. (1881). Ueber die Augenuntersuchungen in den hoheren schulen zu Darmstadt, Abtheilung fur Gesunheitspflege, Marz. [Cited and discussed in Tinker and Paterson, 1929]
Youngman, M. and Scharff, L.V. (1998). Text width and border space influences on readability of GUIs, Proceedings of the Twelfth National Conference on Undergraduate Research, 2, 786-789.