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What is the optimal line length when reading prose text from a monitor?
Certain aspects of usability have been researched for over 120 years.
One active area of 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 4 inches
(100 millimeters). He stated further that the maximum never should exceed
6 inches (150 mm). The same year Javel (1881) reported that line lengths
should be no longer than 3.6 inches (90 mm). Two years later, Cohn (1883)
confirmed that 3.6 inches (90 mm) was the best length, and that 4 inches
(102 mm) was the longest admissible line length.
These recommendations were for book, magazine and newspaper publishers,
and assumed the use of 10-point black characters typeset on white paper.
There only were about 2,000 typewriters in use in the early 1880s. Almost
50 years later there was another flurry of activity on this topic.
One of the best studies was done by Tinker and Paterson in 1929. Using
10-point black type on white paper, they found that line lengths between
3 inches and 3.5 inches (75 to 90 mm) yielded the fastest reading performance.
Paragraphs with line lengths of 7.3 inches (185 mm) were read slowest.
The authors proposed that longer line lengths obviously require greater
lateral eye movements, which seemed to make it more likely that users
would lose their place within the text.
As computer monitors were used more in these studies, longer line lengths
seemed to enable faster reading performance. Duchnicky and Kolers (1983)
found that a full screen length of 7.4 inches (187 mm) resulted in 28%
faster reading times over a 1/3 screen length of 2.4 inches (62 mm). In
fact, both full screen and 2/3 screen line lengths were read reliably
faster than the 1/3 screen length.
Dyson and Kipping (1998) also found that reading rates increased as characters
per line increased. In their study using 12-point type, the 4-inch line
length produced the slowest reading rate and the 7.3 inch line length
produced the fastest. However, users preferred the 4-inch (102 mm) line
lengths. They also reported that even though a single wide column was
read reliably faster than three columns, users preferred the 3-column
format.
Youngman and Scharff (1999) used 12-point type and found that with no
margins, an 8-inch line length elicited the fastest overall reading speed,
when compared with 4 and 6 inch line lengths. Again, users preferred the
4-inch line length.
Bernard, Fernandez and Hull (2002) had participants read 12-point prose
text with line lengths of 9.6 inches (245 mm), 5.7 inches (145 mm) and
3.3 inches (85 mm). They found no reliable differences in the average
reading speed for the differing line lengths. Their adult subjects preferred
the two shorter line lengths.
The research also suggests that line lengths (columns) can be too short.
Dyson and Kipping (1998) found that a line length of 5.5 inches (140 mm)
was read reliably faster than a narrower 1.8 inch (46 mm) line length.
A more recent study by Dyson and Haselgrove (2001) reported that a 4-inch
line length resulted in faster reading than the shorter line length of
1.7 inches
What can we conclude when users are reading prose text from monitors?
Users tend to read faster if the line lengths are longer (up to 10 inches).
If the line lengths are too short (2.5 inches or less) it may impede rapid
reading. Finally, users tend to prefer lines that are moderately long
(4 to 5 inches).
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References
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Bernard, M., Fernandez, M. and Hull, S. (2002), The effects of line length
on children and adults' online reading performance, Usability
News, 4.2. [This article had a line length of 9 inches on the screen
(1024x768 pixel resolution) and 6.2 inches when printed]
Cohn, H. (1883), Die Hygiene des Auges in den Schulen,
Leipzig. [See Tinker and Paterson, 1929]
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 Haselgrove, M. (2001), The influence of reading speed
and line length on the effectiveness of reading from a screen, International
Journal of Human-Computer Studies, 54, 585-612.
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.
Dyson, M.C. and Kipping, G.J. (1997), The legibility of screen formats:
Are three columns better than one? Computers &
Graphics, December, 21(6), 703-712
Javel, E. (1881), L'evolution de la typographic consideree dans ses rapports
avec l'hygience de la vue, Revue Scientifique,
1, 802-813. [See Tinker and Paterson, 1929]
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. [This journal article
had a line length of 3.8 inches (97 mm)]
Weber, A. (1881), Ueber die Augenuntersuchungen in den hoheren schulen
zu Darmstadt, Abtheilung fur Gesunheitspflege,
Marz. [See Tinker and Paterson, 1929]
Youngman, M. and Scharff, L. (1998), Text
width and margin width influences on readability of GUIs. [This Web
page had a line length of 15 inches on the screen (1024x768 pixel resolution)
and 7.8 inches when printed]
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