Posted on February 17, 2008 by Alex Poole

Back in 1998 when Times New Roman was still widely used on the web, my then boss made sure we always designed our web sites with Arial, as she hated the look of serif fonts on the web. Was it the case that sans serif fonts were more legible, or was it just a matter of taste?

In 2003 as part of my master’s degree I reviewed over 50 empirical studies in typography and found a definitive answer.

Arguments in favour of serif typefaces Serifs are used to guide the horizontal “flow” of the eyes; The lack of serifs is said to contribute to a vertical stress in sans serifs, which is supposed to compete with the horizontal flow of reading ( De Lange et al., 1993 )

These are the most common claims when trying to make a case for the utility of serifs. However, serifs cannot in any way be said to “guide the eye”. In 1878 Professor Emile Javal of the University of Paris established that the eyes did not move along a line of text in one smooth sweep but in a series of quick jerks which he called saccadic movements (Spencer, 1968, p. 13 ; Rayner & Pollatsek, 1989, pp. 113-123 ). Unfortunately many graphic designers and typographers continue to use this rationale for the existence of serifs, due to a lack of communication and cooperation with the research community.

Serifs are used to increase spacing between letters and words to aid legibility

Serifs are not required to control letter and word spacing – in fact, serifs would be woefully inadequate for this purpose. In traditional letterpress systems, spacing is achieved with small pieces of metal inserted between the letters, and by the spacing between the letter form and the edge of the print block. Spacing is even easier to manipulate with modern computerised typesetting equipment. ( Sassoon, 1993 ; Rubinstein, 1988 )

Serifs are used to increase contrast (and irregularity) between different letters to improve identification

Well established research has shown that whole words can be recognised just as quickly as letters during an eye fixation and that single letters can be identified quicker when embedded in a word. Such a ‘Word superiority effect’ would indicate that serifs are not needed for distinguishing between single letters ( Reynolds, 1979 ).

Serifs are used to bind characters into cohesive ‘word wholes’

The simple Gestalt created by spaces between words would be enough to bind letters into ‘wholes’. Furthermore, other features such as character ascenders and descenders should have a much greater effect on word recognition than serifs ( Poulton, 1965 ).

Readers prefer body text set in serif typefaces, so they must be more legible

Many studies conducted in the past did indeed find a preference for serif typefaces (Tinker, 1963 ; Zachrisson, 1965 ). However, Tinker commented that perceived legibility was due to a great extent to familiarity with the typeface. 40 years ago sans serif typefaces were not as common as they are now, and if these studies were repeated, it would not be surprising to find completely different results. Indeed, more recent studies have shown that computer users prefer sans serif typefaces for body text online ( Boyarski et al., 1998 ,Bernard et al., 2000-2001 , Tullis et al., 1995 , Reynolds, 1979 ).

What is important to bear in mind is that in almost all legibility studies, reader preference or perceived legibility tends to be inconsistent with user performance ( Lund, 1999 ).

Serifs are used for body text because sans serif causes fatigue

It is often claimed that reading large amounts of body text set in sans serif causes fatigue, but there is no evidence to support this, as measuring fatigue has not been a concern in the vast majority of legibility research comparing serif and sans serif typefaces.

Furthermore, “no satisfactory objective method of measurement has been devised. Subjective assessments of fatigue are subject to modification by a great many factors which may be totally unrelated to the experimental situation”. ( Reynolds 1979, p313 )

Arguments in favour of sans serif typefaces Serifs are just an historical artefact

This could be true to a great extent, especially since claims attempting to justify serifs in retrospect have been less than convincing.

Many researchers attribute the origin of serifs to the Romans, some claiming that “Roman masons … terminated each stroke in a slab of stone with a serif to correct the uneven appearance made by their tools”. ( Craig, 1980; in Bix, 2002 ). Others state that “design by brush before execution in stone gave rise to … tapering serifs at the terminals of many strokes”. ( Bigelow, 1981; in Rubinstein, 1988, p10 ).

What ever their origin, serifs have been around for so long that perceived legibility is very likely to have been affected by familiarity – readers tend to rate as more legible the typefaces they are most used to ( Tinker, 1963 ; Zachrisson, 1965 ).

Sans serif are better on the web

Although studies of screen reading show no difference between reading from screen and from paper ( Dillon, 1992 ; Bernard, 2001 ), there could be some validity to this argument.

When typefaces are digitised for use on computers, the letter forms have to fit within a relatively small pixel grid, often leading to what are called the “jaggies” ( Rubinstein, 1988). Many web professionals such as graphic designers claim that this relatively low resolution cannot render effectively enough the fine finishing strokes of serif typefaces, and that sans serif typefaces lend themselves more naturally to being digitised, and come out cleaner and thus more legible.

However, this has not been borne out by recent evidence ( Bernard, 2001 , Boyarski et al., 1998 , Tullis et al., 1995 , De Lange ), that shows no difference in legibility between serif and sans serif font on the web.

Sans serif is better at small sizes. Sans serif fonts survive reproduction and smearing because of their simple forms

Some research has shown that serifs may actually become visual noise at very small sizes, detracting from the main body shape of the letter form ( Morris, et al., 2001 ). However, this has not been confirmed in tests of continuous reading ( Poulton, 1972 ). Other factors such as stroke thickness, counter size and x-height are likely to have a far greater effect in preserving the overall identity of a letter form whether it be through smearing or size reduction ( Poulton, 1972 ; Reynolds, 1979 ).

Sans serif is better for children learning to read

Books produced for children are often printed with sans serif text as teachers claim that the simplicity of the letter shapes makes them more recognisable ( Coghill, 1980) , Walker, 2001 ). But studies with child participants have found no difference in their ability to read either style of typeface. ( Coghill, 1980) ; Zachrisson, 1965 , Walker, 2001 )

3. Conclusion

What initially seemed a neat dichotomous question of serif versus sans serif has resulted in a body of research consisting of weak claims and counter-claims, and study after study with findings of “no difference”. Is it the case that more than one hundred years of research has been marred by repeated methodological flaws, or are serifs simply a typographical “red herring”?

It is of course possible that serifs or the lack of them have an effect on legibility, but it is very likely that they are so peripheral to the reading process that this effect is not even worth measuring ( Lund, 1999 ).

Indeed, a greater difference in legibility can easily be found within members of the same type family than between a serif and a sans serif typeface. ( Tinker, 1963 , Zachrisson, 1965 ). There are also other factors such as x-height, counter size, letter spacing and stroke width which are more significant for legibility than the presence or absence of serifs.Poulton, 1972 ; Reynolds, 1979 )

Finally, we should accept that most reasonably designed typefaces in mainstream use will be equally legible, and that it makes much more sense to argue in favour of serif or sans serif typefaces on aesthetic grounds than on the question of legibility. ( Bernard, 2001 ; Tinker, 1963 )