The first systematic analysis of the legibility of serif and sans serif typefaces among children was carried out by Zachrisson (1965, pp. 97–108). Groups of 36 boys in Grade 1 (aged 7–8 years) were drawn from two Swedish schools. At one school, reading instruction was based on material printed in a serif typeface; at the other school, it was based on material printed in a sans serif typeface. The boys were tested individually and were asked to read aloud two pages of text. They were randomly assigned to receive text that was printed in one of two serif typefaces (Bembo or Nordisk Antikva) or one of two sans serif typefaces (Gill Sans or Mager Konsul). Zachrisson analysed the number of errors made when reading the text. There was a significant variation among the four typefaces, but the overall difference between the serif typefaces and the sans serif typefaces was not significant, and the difference between the two schools (and hence the typefaces used for reading instruction) was not significant.

In a subsequent experiment (pp. 109–115), Zachrisson drew a sample of 24 boys and 24 girls from Grade 4 (aged 10–11 years) of the school where instructional material was printed in a sans serif typeface. They were asked to read silently two different passages, but their reading was interrupted from time to time by comprehension questions. Once again, the passages were printed in one of two serif typefaces (Bembo or Fairfield) or one of two sans serif typefaces (Fin Grotesk or Gill Sans). Each participant read one passage in a serif typeface and the other in a sans serif typeface. There was no overall difference in the time taken to read each passage between the serif typefaces and the sans serif typefaces, and there was no significant variation among the four typefaces.

For his next experiment (pp. 115–121), Zachrisson presented individual words in isolation by means of a tachistoscope; alternate words were presented in a serif typeface (Mediaeval) and in a sans serif typeface (Mager Futura). The sample consisted of 12 boys in Grade 1 at each of the schools involved in the first experiment, together with six boys and six girls in Grade 4 at the school involved in the second experiment. The words were presented for 40 ms to the younger children and for 20 ms to the older children. Zachrisson analysed the number of words correctly reported, with partial credit for words that were incorrectly reported. There was no significant difference between the two typefaces for either the younger children or the older children, and no significant difference between the two schools.

Zachrisson employed the same research design and materials in a further study that employed Weiss's (1917) focal variator (pp. 121–124), which was described in Sect. 1.2. In this case, he analysed the threshold at which the blurred image of a word was correctly recognised. The difference between the two typefaces was not significant for either the younger children or the older children. The difference between the two schools for the children in Grade 1 was highly significant, but Zachrisson did not report the direction of the difference. Zachrisson also adopted the same research design using a perimeter, which is a device for presenting visual material in peripheral vision (pp. 124–128). This study failed to yield any significant results, and he inferred that this was not a useful way to measure the legibility of typefaces.

Zachrisson had also asked the children who participated in his first two experiments to rank order the four typefaces in which the passages had been presented (pp. 131–132). They were instructed as follows: "The point is to say which of these you find most legible—inviting, pleasant, easy, to read, and in which order you want to put them according to their legibility. Which one do you like best, next best, third and least?" (p. 131). There was no significant difference in the ranks assigned to the four typefaces, no significant difference between the children in Grade 1 and the children in Grade 4, and no significant difference between children in Grade 1 at the two schools (and hence between the typefaces used for reading instruction). Zachrisson concluded on the basis of all his findings that "*there is no significant difference, in objectively measured legibility, or subjective opinion regarding ease of reading between the OF* [serif] *and SS* [sans serif] *type faces*" (p. 132, italics in original).

## **7.4 Other Research with Children**

Weiss (1978, 1982) asked 145 boys and girls in Grades 3 and 6 (aged 8–9 and 11–12) at two public schools in New York City to express their preferences among printed material that differed in page size, type size, and typeface. Each example was printed as a two-page spread of text but consisted simply of familiar words in a random sequence together with an arbitrary illustration presented in the top, middle, or bottom of the right-hand page. Weiss chose three typefaces that were easily discriminable: a sans serif typeface (Futura) and two serif typefaces (Paladium and Parinesy). The children were divided into three ability groups based on their scores in an achievement test and were interviewed individually about their perceptions and preferences regarding the different page sizes, the different typefaces, and the different positions of the illustrations.

Of the three factors, the typeface was regarded as important by children in Grade 3 but not by children in Grade 6, by boys but not by girls, and by children of medium ability but not by children of low or high ability. Children of low and middle ability tended to prefer the Futura sans serif typeface, whereas children of high ability tended to prefer the Paladium serif typeface. There was no significant difference in preferences between boys and girls or between the children in different grades. When asked to give reasons for their preferences, the children mainly referred to the legibility and the attractiveness of the printed material. As Weiss noted, this pattern is consistent with the results obtained by Tinker and Paterson (1942) in the case of adult readers.

Coghill (1980) carried out an informal study in which 38 children aged about 5 years who were being taught to read using materials printed in a sans serif typeface (Gill Sans) were asked to read aloud sentences printed in that typeface or in a number of serif typefaces: "In almost every case the children found little difficulty in reading alternative typefaces" (p. 257), and any reading errors tended to be repeated across the different typefaces.

Sassoon (1993) described a study in which 50 8-year-old children were shown a short passage in four different typefaces and four different settings and were asked to choose the typeface that they liked best and found easiest to read. There were two serif typefaces, Times Roman and Times Italic, and two sans serif typefaces, Helvetica and a slanting sans serif typeface that Sassoon herself had developed. Their preferences were fairly evenly distributed, and Sassoon argued that children were able to assimilate different typefaces as a result of their exposure to television graphics and other kinds of advertising. These findings led her to promote her own typeface, Sassoon Primary, in material for young readers (Bluhm, 1991). However, using two different procedures, Wilkins et al. (2009) found that children read words in this typeface less quickly (both aloud and silently) than they read words of the same x-height in the sans serif typeface Verdana. Wilkins et al. suggested that this was because, with Sassoon, neighbouring letters tended to use strokes that were more similar in shape.

De Lange et al. (1993) asked 160 schoolchildren to read two pages of text and to mark all occurrences of a particular word. Half received two pages in the same serif typeface (Times Roman), but the other half received the first page in Times Roman and the second page in a sans serif typeface (Helvetica). Each group contained equal numbers of children from each of four schools, equal numbers of children from Years 4 and 6, and equal numbers of children with high and low academic performance. De Lange et al. calculated the scanning speed on each page by dividing the number of marked targets by the scanning time and then calculated the gain in scanning speed from the first page to the second. There was no sign of any significant difference between the two conditions in the gain scores obtained by the children in either year. De Lange et al. concluded that there was no significant difference between the legibility of Times Roman and Helvetica as measured by a scanning process.

Walker and Reynolds (2003) presented excerpts from a children's reading book to 24 children aged 5–7 years in either a serif typeface (Century) or a sans serif typeface (Gill Sans) with or without infant characters. The typefaces were balanced across the four excerpts in different children. Walker and Reynolds measured the time taken to read each excerpt aloud as well as the errors that the children made in doing so. There was no significant variation in the time taken or in the number of errors made across the four typefaces. Walker and Reynolds took these results to confirm Coghill's (1980) view that children do not find non-infant characters problematic. The children were also asked to express their preferences among the typefaces: eight expressed no preference, but eight expressed a preference for Gill Sans without infant characters, and five expressed a preference for Gill Sans with infant characters.

Ripoli (2015) noted that in many Spanish-speaking countries children are taught to read using material printed in a cursive typeface before moving on to serif and sans serif typefaces. He tested 115 children who had been taught to read using a cursive typeface in the final year of preschool. They were asked to read aloud six short texts taken from a children's book in Spanish, each in one of six typefaces: a cursive typeface (Escolar 1), two serif typefaces (Sylfaen and Times New Roman), and three sans serif typefaces (Arial, Lexia Readable, and Comic Sans). Assignment of the six typefaces to the six texts was counterbalanced across different children, and the x-height of the lowercase letters in each typeface was matched to that of Arial 14-point type. There was significant variation across the six typefaces in the number of incorrect line breaks made by the children, but no significant variation in the number of words read correctly per minute or in the number of errors that they made. Ripoli observed that, despite having been taught to read using a cursive typeface, the children had no difficulty reading using non-cursive typefaces, even using Lexia Readable (which they had not previously encountered). There was also no difference in their performance on the serif typefaces and on the sans serif typefaces.

Griffiths (2020) devised the Comparative Rate of Reading Speed Test. This involved two displays, each consisting of 13 lines with 60 characters in each line. The characters were random groups of between one and seven lowercase letters. The first display was printed in black in the serif typeface Times, and the second display was printed in teal in the sans serif typeface Gill Sans. A total of 92 children aged 11–12 years were asked to read the characters aloud and were timed on their reading of the fifth line in each display. The mean times were 40.53 s for the Times display and 34.81 s for the Gill Sans display. The difference between these mean times was highly significant. Griffiths commented that the use of teal for the Gill Sans display had been "a concession to light sensitive subjects" (p. 11). He suggested that the result was due to binocular deficiency (i.e., unstable co-ordination of the eyes), but this only affects 15% of the general population (Hargreaves, 2008). He acknowledged that the effect of typeface had been confounded with that of colour, and he argued that the latter was the more important variable, possibly due to a reduction in contrast. However, since all of the children saw the displays in the same order, the result might simply have represented a practice effect.

## **7.5 Letter Reversals**

It has been known for more than a century that children who are learning to read tend to confuse pairs of lowercase letters that are mirror images of each other (e.g., *b* and *d*; *p* and *q*) (Mach, 1897, p. 50). This appears to be true in all cultures that use the Western alphabet in reading and writing (Goikoetxea, 2006). It is mainly apparent in the final year of kindergarten and the early years of compulsory education, and it is apparent in a variety of tasks extending beyond reading aloud and writing to dictation (Thompson, 2009). Such errors are found in normal readers as well as in children with learning disabilities and children who are dyslexic; nevertheless, they become less common in older children as their reading develops (Cossu et al., 1995; Davidson, 1936; Kennedy, 1954). (They are sometimes seen in older neurological patients and occasionally in healthy older adults: Balfour et al., 2007.)

In the regular forms of most sans serif typefaces, the relevant letter pairs are exact mirror images of one another (see Fig. 1.1 in Sect. 1.2). Some authors have argued that the addition of serifs enhances legibility by making individual letters more discriminable from one another (e.g., Legros, 1922, p. 11; McLean, 1980, pp. 42–44). Yule (1988) and Wiebelt (2004) argued in particular that serifs help to differentiate between confusable letter pairs because they are no longer exact mirror images of each other. (For instance, the left-hand panel of Fig. 1.1 shows that, in both the letters *b* and *d*, the serifs are on the left-hand side of the ascenders.) However, other authors have argued that, even with the addition of serifs, the relevant pairs of lowercase letters do not differ appreciably from each other (e.g., Potter, 1949, p. 11). Indeed, Lockhead and Crist (1980) found that more explicit cues were needed to enable children to discriminate between such letter pairs.

Evaluating the two positions is difficult, because most researchers who have described letter reversals in young children have not specified the typeface used in their reading tests. It is therefore impossible to say whether the children had been asked to read letters printed in serif or sans serif typefaces. Popp (1964) did specify the use of a serif typeface (Century) to present lowercase letters in a two-alternative forced-choice experiment where children had to match letters presented on a touchsensitive projection screen. Their error rate was highest on the pairs *b*–*d* and *p–q*, thus confirming that mirror reversals still occur with letters that are presented in a serif typeface.

In the study mentioned in Sect. 7.4, Ripoli (2015) examined the number of letter reversals made by 115 children when reading six texts printed in six different typefaces. The number of letter reversals was least for texts printed in the cursive typeface Escobar 1 and the sans serif typeface Lexia Readable, where there are additional cues that serve to differentiate the critical pairs of lowercase letters. However, there was no significant variation in the number of letter reversals for texts printed in the other four typefaces: two serif typefaces (Sylfaen and Times New Roman) and two sans serif typefaces (Arial and Comic Sans). These results imply that, in the absence of additional cues, the presence of serifs does not in itself help children to discriminate between pairs of letters that are otherwise mirror images of each other. In general, mirror reversals in children's reading and writing relate to structural properties of the relevant alphabet and not to the particular typeface used to render that alphabet (Treiman et al., 2014).

## **7.6 Older Readers**

Vanderplas and Vanderplas (1980) suggested on the basis of interviews carried out with older people that many did not read as much as they would have liked because of difficulties with illegible type, although some publishers do produce large-type versions of newspapers and books intended for older readers. The researchers asked 28 volunteers aged between 60 and 83 to read 30 passages of 30–33 lines taken from Samuel Butler's novel, *Erewhon*. The 30 passages were presented in one of five type sizes from 10 to 18 points and in one of six typefaces. Three were serif typefaces (Century Schoolbook, Times Roman, and Bodoni), and three were sans serif typefaces (Helvetica, Spartan, and Trade Gothic). The type sizes and the typefaces were counterbalanced, but the order of the passages reflected the narrative structure of the novel. After reading each passage, the participants were given a short test of their comprehension to ensure that they had actually read the material, and they then rated the passage on six aspects of its presentation using a 7-point scale.

Their reading speed was significantly faster for passages with serif typefaces than for passages with sans serif typefaces, but there was also significant variation in reading speed across the six typefaces: Century Schoolbook yielded the fastest reading speed, but Spartan yielded the slowest. Their reading speed generally tended to increase with the type size. The participants also rated passages with serif typefaces more positively than passages with sans serif typefaces on their apparent size, how easily they could be read, and how easily they could be understood. They also rated 12-point typefaces as being the easiest to read.

One situation in which older readers encounter problems is in reading labels on their medication, regardless of whether the labels are prepared using dot-matrix printers (Zuccollo & Liddell, 1985) or more advanced laser printers (Watanabe et al., 1994). Smither and Braun (1994) asked 19 younger adults (mean age 25.48 years) and 20 older adults (mean age 71.05 years) to read the labels on 18 prescription bottles printed in a serif typeface with proportional spacing (Century Schoolbook), a monospaced slab serif typeface (Courier), or a sans serif typeface with proportional spacing (Helvetica). They read more slowly and made more errors on the labels printed in Courier than on the labels printed in either Century Schoolbook or Helvetica. The older adults also read more slowly and made more errors than the young adults when reading labels printed in Courier.

Smither and Braun suggested that the participants might have had problems because of the curvature of medication bottles. They repeated their experiment with new participants and with the 18 labels placed on a flat surface. These participants once again read the labels printed in Courier more slowly, but they did not make more errors than on the labels printed in Century Schoolbook or Helvetica. The older adults read more slowly than the young adults across the board, but they did not make more errors. Smither and Braun inferred that reading medication labels was more effective if they were printed with proportional spacing (Century Schoolbook or Helvetica) than if they were printed with monospacing (Courier). However, the presence or absence of serifs seemed to have little or no effect on the legibility of medication labels.

## **7.7 Conclusions**

As novice readers, young children may be disproportionately affected by different typefaces. The use of different typefaces may also affect how readily children acquire the ability to read. Research by Burt (1959), Burt et al. (1955) and Kerr (1926) is often cited in support of the idea that serif typefaces are more legible. However, their accounts are inadequate and contain many contradictions. Zachrisson (1965) provided a more thorough account of the role of typographic variables in reading among children of different ages using various research methods and found no evidence for any difference in legibility between serif and sans serif typefaces. Subsequent research by other investigators has tended to confirm Zachrisson's conclusions. It has been known for more than 100 years that children tend to confuse letters that are mirror images of each other (such as *p* and *q*). This phenomenon occurs with both sans serif letters (which are true mirror images) and serif letters (which are not). Older readers tend to suffer from visual problems which may depend on typographical factors. This is of practical importance, as in the design of labels for medication containers. Nevertheless, there are no differences in the reading capability of older readers when presented with material printed in serif and sans serif typefaces.

**Open Access** This chapter is licensed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license and indicate if changes were made.

The images or other third party material in this chapter are included in the chapter's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the chapter's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder.

## **Chapter 8 Readers with Disabilities**

## **8.1 Readers with Visual Impairment**

Nolan (1959) tested 264 children with visual impairment aged between 8 and 20. Half of the children counted as legally blind, but the others did not. Within each group, the children were randomly assigned to different subgroups to read material presented in either 18-point type or 24-point type in either a serif typeface (Antique with Old Style) or a sans serif typeface (Metrolite Medium). The material itself consisted of 72 paragraphs, each of about 90 words; after reading each paragraph, the children had to answer a short comprehension question by choosing one of five alternative words. Nolan measured the number of paragraphs that they had read in 30 min, statistically adjusted for variations in their reading comprehension.

The results showed that the children with better vision read faster than the children with poorer vision, and that the material presented in Antique with Old Style was read more quickly than the material presented in Metrolite Medium There was no significant difference in reading speed between the two type sizes, and there were no significant interactions among the effects of reading ability, type size, and typeface. Nolan commented that Metrolite Medium had needed a greater line length than Antique with Old Style, and she suggested that it was this feature rather than the absence of serifs that explained the slower reading time. In fact, Nolan had standardised the line length at 8.5 in. (21.6 cm) in all four sets of material. Consequently, the material that was presented in Metrolite Medium would have needed more lines, which suggests that it was the number of lines rather than the presence or absence of serifs that had given rise to differences in reading performance between the two typefaces.

## **8.2 Shaw's Research**

During the 1960s, Alison Shaw was commissioned by the UK Library Association (now the Chartered Institute of Library and Information Professionals) to study the reading capabilities of people designated as *partially sighted*, defined as those who had difficulty reading normal sized book print but whose sight could not be fully corrected by the use of spectacles. The findings of the research were published as a formal report (Shaw, 1969). Shaw also published three short journal articles about the study, but these omit key information about her research methods and data analyses, and so this account is based on her formal report.

Shaw decided to investigate her participants' capacity for reading continuous printed text at a close reading distance (p. 9). She chose to investigate separate samples of adults and children, with a primary focus on the former (p. 17). She identified four aspects of the text which might be important: typeface, type weight, type size, and type spacing. With regard to typeface, she compared Plantin, a serif typeface which had been developed in 1913 by the Monotype Corporation, and Gill Sans, the sans serif typeface developed in 1928 by Eric Gill. She argued that these were representative examples of serif and sans serif typefaces that were relatively similar in terms of their x-height and their width (p. 23). With regard to weight, she compared the medium and bold versions of these two typefaces. With regard to size, she used 12-, 14-, 16-, 18-, 20-, and 24-point sizes. Each participant was tested to determine their visual acuity, and they received material in two successive point sizes that were just below and just above their acuity threshold (e.g., 16-point and 18-point sizes) (p. 24). With regard to spacing, she used four combinations of inter-letter, inter-word, and inter-line spacing (pp. 24–25), which yielded 32 different combinations of typeface, weight, size, and spacing.

Each participant received four of these 32 combinations. The materials consisted of short passages of common words that were combined to yield grammatical but semantically anomalous sentences (e.g., "Hungry bridges describe expensive farmers": p. 32). Each of the passages consisted of six sentences printed in five lines containing 38–41 characters. One passage was assigned to each of the 32 conditions, but a pre-test was carried out using ten readers with normal vision to ensure that the 32 passages were of comparable difficulty (p. 33). The conditions assigned to different participants and the order of their administration were counterbalanced using Graeco-Latin squares (p. 29).

Shaw measured the number of words in each passage that were read aloud correctly and the time taken to read them. She used this information to calculate the average time per correct word and normalised the latter by dividing it by the average time per word taken by the normal readers to read each passage. There was a positive correlation between the mean and the variability of the normalised data, and so the logarithms of these data were used. Finally, the four transformed values for each participant were expressed as deviations about their mean value in order to eliminate differences among the participants (p. 37). Multiple regression analyses were then used to identify the factors that were responsible for significant variations in performance.

A total of 288 adults with visual impairment were recruited through government agencies and voluntary associations. Shaw compared their characteristics with those of the population according to national statistics, and she concluded that the sample was broadly representative of the national population of adults with partial sight (p. 53). The multiple regression analysis found that an increase in type size from the smaller size to the larger size led to an improvement of reading performance of 16%; an increase in the type weight from medium to bold led to an improvement of 9%; changing the typeface from serif to sans serif led to an improvement of 4%; and variations in spacing did not lead to a significant change in reading performance (p. 50). Shaw noted that her findings contradicted "traditionalist views that a serif face is always more legible than a sans serif" (p. 61), and she concluded that the effect of differences between the two typefaces was of minor importance compared with the effects of size and weight (p. 65).

Shaw compared various subgroups in the sample of adults with visual impairment. The most common causes of visual impairment (some adults had more than one cause) were:

Comparing these subgroups, changing the typeface from serif to sans serif had significantly benefited participants with macular degeneration but not the other three subgroups (p. 50). Independent of this, 72 exhibited a congenital impairment, having been affected since birth or early childhood, whereas 112 exhibited an acquired impairment, having been affected since the age of 50 (p. 43). Changing the typeface from serif to sans serif had benefited the latter but not the former.

Shaw also recruited 48 children with visual impairment who had a reading age of at least 11 from schools for partially sighted children. Once again, Shaw compared their characteristics with those of the national population, and she concluded that they were representative of older, brighter children in schools for partially sighted children (p. 56). The multiple regression analysis found that an increase in type weight from medium to bold led to an improvement of reading performance of 7%, but that variations in type size, typeface, or spacing did not lead to a significant change in reading performance (p. 50). The most common causes of visual impairment were myopia, cataract, and nystagmus (which causes visual impairment by disrupting the normal pattern of eye movements), but these subgroups were too small for any further statistical analysis. After they had read the passages, the children were asked which of the four examples they thought was the clearest. There was no correlation between the children's personal subjective judgement and their objective reading performance (p. 49).

Shaw concluded that the sans serif typeface was slightly more legible than the serif typeface for her adult readers, but that there was no measurable difference for the children (p. 65). This might be taken to suggest that the advantage of the sans serif typeface was due to the adults' increased familiarity and experience in reading such typefaces. However, there are two problems with Shaw's study. First, although she carried out a large number of statistical tests on her data, she did not control for the possibility of Type I errors. As a result, some of the statistically significant differences which she found might have been spurious results due to chance variation.

Second, and more fundamentally, Shaw's focus on readers with visual impairment meant that she ignored the performance of the normal readers in her study. In normalising the performance of her participants on each passage against the performance of normal readers on the same passage, she ignored the possibility that the normal readers themselves might have shown significant differences between the serif and sans serif typefaces. Suppose that the readers with visual impairment produced reading speeds of 50 words/min on a passage printed in Plantin and 60 words/min on a passage printed in Gill Sans, and that the normal readers produced reading speeds of 100 words/min and 120 words/min on these passages. Normalising the former data would have yielded scores of 0.5 for both typefaces. (Taking logarithms and deviations about the mean value would not have changed this situation.) In other words, the normalisation process might well have obscured differences in legibility in *both* normal readers *and* those with visual impairment. Unfortunately, Shaw did not present the descriptive statistics to enable readers to establish whether or not this was a possibility.

## **8.3 Children in Special Education**

Pittman (1976) compared 48 children with learning disabilities and 48 nondisabled children in their reading comprehension. She showed them stories consisting of five paragraphs and then administered ten sentence-completion questions. Each story was presented over four trials. The children in each group received stories in one of four typefaces: one was in a serif typeface (Pica), two were in sans serif typefaces (Gothic and Primary), and one was in a cursive typeface (Script). Not surprisingly, the children's performance increased over the four trials. The nondisabled children obtained higher scores than did the children with learning disabilities. However, there was no significant difference among the children' scores on the four typefaces. Pittman concluded "that the style of type is not an important variable in the reading comprehension of LD [learning-disabled] and normal children" (p. 115). It might be noted that the results obtained by the comparison group of nondisabled children confirm the conclusion of Chap. 7 that there is no difference in the legibility of serif and sans serif typefaces among normal young readers.

Section 7.4 mentioned a study by Sassoon (1993) in which nondisabled children were shown a short passage in four different typefaces and were asked to choose the typeface that they liked best. Sassoon repeated this study with 50 children who were in special education and aged between 8 and 13. Apart from describing them as having "learning difficulties" (p. 158), she did not mention what their special needs actually were. In this case, there were clear differences: 44% chose the slanting sans serif typeface, 28% chose the serif Times Italic, 18% chose the sans serif Helvetica, and 10% chose the serif Times Roman. Sassoon attributed the low preference for Times Roman to the fact that its pronounced serifs and short descenders affected the identification of certain letters. However, in Sect. 7.4 it was noted that Sassoon had developed the slanting sans serif typeface herself and had been promoting it for use in material for young readers. It would have been better if Sassoon had employed assistants who were blind as to the specific research hypotheses to avoid the possibility of researcher bias.

Haugen (2010) tested 14 children in special education in Grades 3–6 (aged 8–11). Once again, apart from describing them as having "mild special education needs" (p. 17), she did not discuss what their special needs actually were. She asked them to read aloud four passages of between 260 and 440 words printed in different typefaces: Bookman, a serif typeface; Comic Sans, a sans serif typeface based on comic-book lettering; Helvetica, a more regular sans serif typeface; and Times, another serif typeface. Each passage took about 5–10 min to read. However, Haugen did not time the children exactly but instead monitored their behaviour. Finally, she showed them all four of the passages that they had read and asked them to say which style of letters they had found the easiest to read and which they liked the best (pp. 83–93).

All the children completed all four passages, but they appeared more restless when reading the passages in Comic Sans and Times than when reading the passages in Bookman and Helvetica. Haugen commented that the issue was not the difference between serif and sans serif typefaces but the design of each typeface when compared with that of the others. The number of words read incorrectly was similar across the four typefaces, although Times yielded the fewest while Comic Sans yielded the most. The children were more likely to skip words printed in the two serif typefaces than those printed in the two sans serif typefaces, whereas they were more likely to pause when reading words printed in the two sans serif typefaces than when reading words printed in the two serif typefaces. Finally, they were more likely to run together two successive sentences printed in Comic Sans than those printed in the other typefaces (pp. 121–128).

Nine of the 14 participants thought that one of the serif typefaces was the easiest to read, and five thought that one of the sans serif typefaces was the easiest to read, four of whom chose Comic Sans. However, their choice did not seem to bear any relationship to their actual reading performance. Moreover, 12 of the 14 participants chose a sans serif typeface as the one they liked the best (of whom eight chose Comic Sans), one chose a serif typeface, and one insisted on choosing a serif typeface *and* a sans serif typeface (pp. 129–139). Haugen argued that their preferences had been influenced by their prior experience of sans serif typefaces on game systems, computers, cellular phones, and other electronic devices (pp. 164–165).

## **8.4 Readers with Congenital Visual Impairment**

Uysal and Düger (2012) evaluated the effects of a 3-month training programme in 35 children with visual impairment at a Turkish primary school. Their preferences for different typefaces were assessed before and after the programme by showing them a 20-word sentence in Turkish in five different typefaces (Arial, Comic Sans, Tahoma, Times New Roman, and Verdana) and ten different type sizes. Their reading speed was averaged across all the typefaces and sizes. Before the programme, they preferred the sans serif typefaces such as Verdana (11 children) or Arial (8 children) as opposed to the serif typeface Times New Roman (3 children). The programme initially adopted their preferred typeface but gradually incorporated the other typefaces. It led to a significant increase in both their reading speed and their writing speed, but not in the judged legibility of their handwriting. After the programme, most children indicated that they were comfortable with any of the typefaces except for the sans serif Tahoma.

Skilton et al. (2018) conducted a focus group that involved eight people with deaf-blindness. Such individuals are born with a hearing loss and develop visual impairment during their early childhood. The aim of the focus group was to identify the participants' accessibility needs for their involvement in future research. Their recommendations included the provision of printed materials in a large size (18-point or higher) and in a sans serif typeface such as Arial. However, Skilton et al. acknowledged that these were among the recommendations that were typically provided for improving the accessibility of information of deaf-blind people. Their account left it unclear whether these recommendations were based on their own negative experiences with serif typefaces or whether they were just repeating back conventional attitudes that they had previously acquired from figures in authority.

## **8.5 Readers with Acquired Visual Impairment**

Prince (1967) suggested that the impact of typographical variables might be different in older people with acquired visual disorders. As mentioned in Sect. 8.2, Shaw (1969) had found an advantage for a sans serif typeface over a serif typeface for those with acquired visual impairment but not for those with congenital visual impairment.

Estey et al. (1990) showed 52 patients with an average age of 69.4 years admitted for cataract surgery a page of text printed in a 12-point sans serif typeface, Univers Medium. Only 65% of the patients said that they could read the text, while 35% found it blurry. Estey et al. then showed the patients two pages of text: One was printed in 14-point Univers Medium, and the other was printed in a 14-point serif typeface, Century Schoolbook. Only 2% of the patients said that they could not read these texts. Of the 52 patients, 65% said that they preferred Univers Medium, 33% said that they preferred Century Schoolbook, while 2% had no preference. Estey et al. argued that material for patients with visual deficits should be printed in 14-point sans serif typefaces.

Campbell et al. (2006) carried out two studies in people with age-related macular degeneration (AMD). Participants were recruited from the members of the Canadian National Institute for the Blind (now the CNIB Foundation). They were asked to compare samples of text printed in six different typefaces using reading aids if necessary. Two were serif typefaces (Times Roman and Lucida), while four were sans serif typefaces (Adsans, Arial, Clearview, and Verdana). Adsans had been devised in 1959 to be used in a small (4.75 point) size in newspaper classified advertisements. It is not available in common computer applications, but it was used as the basis for Verdana. Clearview was devised in the 2000s for use on road signs. In both studies, the participants rated how easy it was to read each typeface on a 7-point scale from "impossible to read" to "very easy to read." In the first study, they also ranked the samples from the easiest to the hardest to read. However, this proved to be rather demanding, and so ranking was not used in the second study.

In the first study, 241 participants aged 50 or older were shown excerpts from Robert Louis Stevenson's novel, *Treasure Island*, all printed in 16-point type. The passage printed in Adsans was given significantly higher ratings than any of the other samples, and it was ranked the easiest to read by more than 50% of the participants. In the second study, 157 participants were shown information leaflets for over-thecounter medicines amended to refer to unfamiliar products and printed in 7-point type. The leaflet that was printed in Adsans was once again given significantly higher ratings than any of the other samples. Campbell et al. remarked that in both studies Times Roman had been given low ratings despite being a relatively familiar typeface, which suggested that the participants were not simply rating the typefaces on the basis of their familiarity. These findings show that people with AMD have a preference for Adsans, but they do not constitute evidence with regard to its objective legibility.

Rubin et al. (2006) asked 43 patients with mild cataract or glaucoma to read texts printed in four different typefaces. One was Tiresias, a sans serif typeface developed for people with impaired vision by the Royal National Institute of Blind People in the United Kingdom. This was compared with the serif typeface, Times New Roman, and two other sans serif typefaces, Foundry Form Sans and Helvetica. Their reading speed was found to be significantly faster with Tiresias than with the other three typefaces. However, although nominally of the same point size, the four typefaces occupied different amounts of horizontal and vertical space. When this factor was statistically controlled, the advantage of Tiresias disappeared. Rubin et al. concluded that variations in typeface had little influence on the reading speed of people with mild to moderate sight problems.

Tarita-Nistor et al. (2013) tested 24 patients with AMD using reading charts printed in Times New Roman, Courier, Arial, and a version of Andale Mono. These required them to read individual sentences presented at progressively smaller sizes. Times New Roman is a serif typeface, and Courier is a slab serif typeface, whereas Arial and AndaleMono are both sans serif typefaces. Times New Roman and Arial are both proportionally spaced, whereas Courier and Andale Mono are both monospaced. Tarita-Nistor et al. measured three aspects of their participants' performance: their reading acuity, which was the smallest print size that could be read without significant errors; the maximum reading speed, which was the highest speed at which text could be read without regard to print size; and the critical print size, which was the smallest print size that could be read with maximum speed. There was no significant variation among the typefaces in either critical print size or maximum reading speed, but there was significant variation in reading acuity: surprisingly, and—contrary to the results of the study by Smither and Braun (1994) that was mentioned in Sect. 7.6—text printed in Courier yielded significantly better reading acuity than text printed in the other three typefaces, but text printed in Arial yielded significantly worse reading acuity than text printed in the other three typefaces.

Hedlich et al. (2018) administered reading charts containing sentences printed in the slab serif typeface Courier New or the sans serif typeface Arial to 16 patients with visual impairment before or after cataract surgery. They found no significant difference between the two typefaces in their reading acuity, in their critical print size, or in their maximum reading speed. One limitation of this study, apart from the small sample size, was that the reading chart printed in Arial was always presented before the reading chart printed in Courier New, so that the researchers had no control over the effects of fatigue or practice. They also asked the participants about their preference between the two typefaces: eight of the participants preferred Arial, four preferred Courier New, and four had no preference.

Nersveen et al. (2018) carried out a postal survey of adults with a wide variety of visual impairments. They identified ten typefaces for consideration. Seven were printed in regular font, including two serif typefaces (Scala and Times Roman) and five sans serif typefaces (Frutiger, Helvetica, Scala Sans, Tiresias, and Verdana). Three were printed in bold font, including one serif typeface (Scala Bold) and two sans serif typefaces (Scala Sans Bold and Tiresias Bold). The participants were a random sample of 5,000 members of the Norwegian Association of the Blind and Partially Sighted. Each typeface was presented in five different body sizes (8, 10, 12, 14, and 16 points, but scaled so that their x-heights matched those of Times Roman), and in ten variations in contrast (from black type on white background to white type on black background), yielding 500 conditions. Each was presented as three or more lines of text, together with a 4-point rating scale in which the response categories were "Easily readable", "Readable with some difficulty", "Difficult to read", and "Unreadable". This yielded a booklet consisting of 50 printed pages.

The participants were instructed to carry out the task only if they were partially sighted and able to read printed text (with a magnifying glass or with supplementary lights if necessary). Completed booklets were returned by 830 participants. Repeatedmeasures tests were employed to compare the ratings given to the serif typefaces and the sans serif typefaces. For typefaces at 12 and 14 points, the difference was not statistically significant. For those at 8, 10, and 16 points, sans serif typefaces received significantly higher ratings than did serif typefaces. Nevertheless, the differences were small in magnitude and only achieved significance because of the very large sample size. A similar pattern emerged when comparing the ratings given to the Scala typefaces and the Scala Sans typefaces (J. Nersveen, personal communication, June 22, 2020).

Although Nersveen et al. described their experiment as a study of the legibility of printed text, their data actually consisted of the participants' ratings of the subjective acceptability of the different typefaces rather than any measure of their objective legibility. The apparent preference for sans serif typefaces is thus consistent with the findings of Estey et al. (1990) and Campbell et al. (2006), although the effect was far less pronounced. One problem is the response rate of only 16.6%. This might be partly explained by the fact that the participants did not receive any personal reward for carrying out the task, although two respondents chosen at random were given a "prize" of a Digital Audio Broadcasting radio worth 1,000 Norwegian kroner. As a result, most of the participants may not have been willing to devote time and effort to a rather burdensome task. Whatever the cause, it does suggest that the study suffered from sampling bias, in that the respondents might not have been representative of the target population.

## **8.6 Readers with Aphasia**

The term *aphasia* covers a wide variety of disorders of spoken language, but a majority of people with aphasia also exhibit impairment of reading (Brookshire et al., 2014). Wilson and Read (2016) tested nine participants who had been diagnosed with mild-to-moderate aphasia as the result of cerebrovascular accidents. They were given a standardised test of reading comprehension that consisted of 35 short paragraphs. In each case, the participants had to choose one of four alternative words or phrases to complete the final sentence. For each participant, the paragraphs were randomly assigned to one of seven conditions. One involved the presentation of the original paragraph in a serif typeface (Times New Roman), and the other six involved different manipulations. For two manipulations, the typeface was amended either to a sans serif typeface (Verdana) or to an ornate cursive typeface (Harrington). The participants achieved significantly higher scores with the sans serif typeface than with either of the other two typefaces. Wilson and Read did not speculate as to why patients with aphasia might find serif typefaces less legible. Some researchers have found that people with aphasia prefer material printed in a sans serif typeface (Rose et al., 2011), but other researchers have not (Haw, 2017, p. 129; Herbert et al., 2019).

## **8.7 Readers with Dyslexia**

The term *dyslexia* refers to a specific disorder of reading that may result from a wide variety of causes (and may be either congenital or acquired). For many years, the British Dyslexia Association (2018) has recommended that documents printed for people with dyslexia should use sans serif typefaces, and this has been taken to encompass teaching materials for students (Shaw & Anderson, 2017). However, the Association did not cite any evidence to support this recommendation. In fact, relevant evidence has been obtained in attempting to evaluate Dyslexie, a typeface that was developed by Christian Boer in 2008 to try to facilitate reading among children and adults with dyslexia (http://www.dyslexiefont.com). It is a sans serif typeface characterised by a relatively large x-height and relatively wide vertical and horizontal spacing between the letters. It is available under licence for both Microsoft Windows and Apple computer systems.

Marinus et al. (2016) recruited 39 children who were undergoing remediation for low progress in reading. They were asked to read aloud four passages, each of 200 words. One passage was presented in a 14-point Dyslexie typeface. A second was presented in 16-point Arial, a sans serif typeface which matched the x-height of the letters in the first passage. A third passage was presented in 16-point Arial with an overall increase in spacing. The fourth passage was presented in 16-point Arial with increased spacing both between words and between letters within words to match the spacing used in the first passage. The order of the conditions and the assignment of the passages to the conditions was counterbalanced across different participants. The children were scored on the number of words that they had read correctly per minute in each of the four conditions. Marinus et al. found that their reading speed in the first condition was significantly faster than in either the second or third, but that it was not significantly different in the fourth condition.

Kuster et al. (2018) carried out two experiments to evaluate the Dyslexie typeface. In the first experiment, 170 children with dyslexia were asked to read aloud two passages at separate sessions. One passage was presented in 12-point Dyslexie; the other was presented in 13-point Arial, adjusted to match the vertical spacing of Dyslexie. The order of the two conditions was counterbalanced across the participants. The children read significantly more quickly and made fewer errors on the second passage than on the first. However, there was no significant difference in either reading time or the number of errors between the typefaces.

In their second experiment, Kuster et al. tested 102 children with dyslexia and 45 children without dyslexia. They were each asked to read aloud three lists of words of varying complexity at three separate sessions. At each session, one list was presented in Dyslexie, whereas the other two lists were presented in the serif typeface Times New Roman and the sans serif typeface Arial, in both cases adjusted to match the x-height and the vertical spacing of Dyslexie. The order of the three conditions and the assignment of word lists to conditions was counterbalanced, and the children were scored on the number of words that they read correctly in one minute. Not surprisingly, the children without dyslexia obtained higher scores than the children with dyslexia, and performance varied inversely with the complexity of the words. However, there was no significant difference in the performance of either the children with dyslexia or the children without dyslexia across the three typefaces.

Finally, Powell and Trice (2020) recruited 36 children with dyslexia. They were each asked to read aloud three stories; each story contained 200 words and was followed by three factual questions to test the children's comprehension. One story was presented in 12-point Dyslexie; the others were presented in 14-point Arial and 14-point Times New Roman, both adjusted to match the horizontal and vertical spacing of Dyslexie. The order of the three stories and the assignment of the stories to the three typefaces was counterbalanced across different children. There was no significant variation across the three typefaces in terms of the mean time that the children took to read the stories, no significant variation in terms of the number of errors that they made, and no significant variation in their comprehension scores.

All three of these studies indicated that the effectiveness of the Dyslexie typeface is due to its increased spacing and not to its different letter shapes. If other typefaces are adjusted to match the spacing used for the Dyslexie typeface, the reading performance of children with dyslexia does not differ across the different typefaces. However, both Kuster et al.'s (2018) second experiment and Powell and Trice's (2020) study show in addition that the reading performance of children with dyslexia does not differ between serif and sans serif typefaces if they are matched in terms of their spacing. This contradicts the recommendation made by the British Dyslexia Association (2018) that documents printed for people with dyslexia should use sans serif typefaces.

## **8.8 Conclusions**

Any differences in the legibility of serif and sans serif typefaces might become more apparent in readers whose visual systems are challenged as the result of disablement. In fact, the modal finding is that there are no differences in the reading capability of readers with a variety of disabilities when they are presented with material printed in serif and sans serif typefaces. It might be thought that children with congenital visual impairment would be more sensitive to typographical factors, but in fact such children rapidly adapt to reading both serif and sans serif typefaces. It has been suggested that the effects of acquired visual impairment might be different from the effects of congenital visual impairment, but both groups appear to be equally proficient in reading serif and sans serif typefaces. A majority of people with aphasia exhibit impairment of reading. In this field, it is often taken for granted that people with aphasia will find sans serif typefaces more legible, but there is only one study with a very small sample of participants that supports this position. Certainly, there is now good evidence that the reading performance of children with dyslexia does not differ between serif and sans serif typefaces when they are matched in terms of their spacing.

**Open Access** This chapter is licensed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license and indicate if changes were made.

The images or other third party material in this chapter are included in the chapter's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the chapter's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder.

## **Chapter 9 General Conclusions to Part I**

## **9.1 Key Findings from Part I**

As was mentioned in Sect. 1.4, Part I has reviewed diverse studies using diverse methods of data collection, and this precludes any formal meta-analysis to integrate the findings. One must instead focus on the most common finding—the *modal* finding—regarding the legibility of serif and sans serif typefaces: superiority of serif typefaces; superiority of sans serif typefaces; or no difference.

The research question is whether there are differences in the legibility of serif and sans serif typefaces when they are used to generate printed material. The modal finding from the research studies that have been reviewed is that there are not. This applies to four out of six experiments on reading letters and words (Sects. 4.1 and 4.3); the two Korean studies yielded contradictory results. It applies to five out of six experiments on reading sentences (Sect. 5.1; see also Sects. 6.1 and 6.2) and to all four experiments on the comprehension of text, whether using measures of speed or accuracy (Sect. 5.2). It also applies to all eight experiments on the reading capability of younger readers and to two of the three experiments on the reading capability of older readers (Chap. 7). Two studies have been cited in support of the supposed superiority of serif typefaces, but these can be discounted: one failed to report any empirical data on the issue (Burt, 1959; Burt et al., 1955), and the other suffered from irredeemable methodological problems (Wheildon, 1990, 2005).

It is unfortunate that there has been relatively little work on the legibility of serif and sans serif typefaces in readers with disabilities as opposed to their subjective preferences for different kinds of typeface (Chap. 8). Two studies found no difference in legibility between serif and sans serif typefaces (Pittman, 1976; Rubin et al., 2006). One found a superiority for serif typefaces among children with congenital visual impairment (Nolan, 1959), but this study seems to have suffered from methodological problems. A fourth study found a superiority for sans serif typefaces among patients with aphasia (Wilson & Read, 2016). It is generally assumed that sans serif typefaces are more appropriate for people with aphasia, and there is an urgent need for more research to evaluate this assumption. Finally, two studies have found that the reading performance of children with dyslexia does not differ between serif and sans serif typefaces when they are matched in terms of the spacing of the letters.

## **9.2 Preferences and Connotations**

With regard to research studies concerned with readers' preferences between serif and sans serif typefaces and the connotations of the two kinds of typeface, the modal finding is that among adult readers there is no overall preference between serif and sans serif typefaces, nor any overall difference in the connotations of serif and sans serif typefaces (Sect. 5.4). Even so, there is a suggestion that readers' preferences and the connotations of serif and sans serif typefaces may vary between different contexts (see Schriver, 1997, pp. 289–303; Zachrisson, 1965, pp. 156–62). This has major implications for educational publishing and educational assessment:

There is a need for research on whether reviewers' evaluations of academic manuscripts and teachers' evaluations of students' assignments are affected by their own preferences and expectations. Nevertheless, the available evidence suggests that these variations in readers' expectations and preferences depend on their prior experience and familiarity with different typefaces and not on any intrinsic properties of the typefaces themselves. Indeed, the results that were obtained by Uysal and Düger (2012) indicate that even readers who are visually impaired will find most typefaces relatively congenial after a gradual period of exposure.

## **9.3 Implications for Previous Assumptions**

Where does this leave previous assumptions about the legibility of serif and sans serif typefaces? There is no support for traditional beliefs that serif typefaces are superior to sans serif typefaces and certainly no support for Morison's (1959) assertion that "the serif is essential to the reading of alphabetical composition" (p. xi). Regarding the American Psychological Association's (2010) insistence that a serif typeface "improves readability and reduces eye fatigue" (pp. 228–229), Perea (2013) remarked: "There are no well-founded theoretical reasons to use of [*sic*] a serif font over a sans serif font—beyond subjective preferences" (p. 16). To this one might add: and there is no convincing empirical support, either.

The assertion contained in *Merriam-Webster's Manual for Writers and Editors* (1998) that "studies of typeface legibility have tended to demonstrate that standard serif typefaces can be read somewhat more easily and quickly than standard sansserif typefaces" (p. 330) is factually incorrect. Finally, the length of the reference list at the end of this book contradicts Kullmann's (2015) statement that there have only been "sporadic" studies on this issue (p. 1), and one can certainly dismiss his assertion that previous research has not led to any clear conclusion. On the contrary, based on the wealth of evidence that has accumulated over the last 140 years, the clear conclusion is that there is no difference in the legibility of serif typefaces and sans serif typefaces when they are used to produce printed material.

## **9.4 The American Psychological Association's Current Position**

The guidelines in the sixth edition of the Association's *Publication Manual* followed those in previous editions. However, a seventh edition was published while this monograph was being written; the new guidelines have already been adopted by the American Educational Research Association and are likely to be adopted by other organisations in the future. This seventh edition takes a rather different approach (American Psychological Association, 2020):

APA [American Psychological Association] Style papers should be written in a font that is accessible to all users. Historically, sans serif fonts have been preferred for online works and serif fonts for print works; however, modern screen resolutions can typically accommodate either type of font, and people who use assistive technologies can adjust font settings to their preferences. Thus, a variety of font choices are permitted in APA style. . . .

Use the same font throughout the text of the paper. Options include

We recommend these fonts because they are legible and widely available and because they include special characters such as math symbols and Greek letters. (p. 44)

An accompanying background paper confirms that the focus of the new guidelines is on the accessibility of typefaces for users with disabilities rather than on their legibility per se (Accessibility, 2020). The paper also refers to the Web Content and Accessibility Guidelines produced by the World Wide Web Consortium, suggesting that it is concerned with reading from screens rather than reading from paper, although this is not made explicit. With regard to the legibility of serif and sans serif typefaces, the paper makes the following statement:

It is a common misconception that serif fonts (e.g., Times New Roman) should be avoided because they are hard to read and that sans serif fonts (e.g., Calibri or Arial) are preferred. Historically, sans serif fonts have been preferred for online works and serif fonts for print works; however, modern screen resolutions can typically accommodate either type of font, and people who use assistive technologies can adjust font settings to their preferences.

Research supports the use of various fonts for different contexts. For example, there are studies that demonstrate how serif fonts are actually superior to sans serif in many long texts (Arditi & Cho, 2005; Tinker, 1963). And there are studies that support sans serif typefaces as superior for people living with certain disabilities (such as certain visual challenges and those who learn differently; Russell-Minda et al., 2007). ("Myth 1," paras. 1–2)

The choice of reference citations in this statement is rather odd. First, in discussing different styles of typeface, Tinker (1963, pp. 46–48) referred to the study by Paterson and Tinker (1932), who used a speed-of-reading test to measure the legibility of each of ten typefaces. Seven were serif typefaces that had been nominated by a large number of editors and publishers as being worthy of study, of which Scotch Roman was used as a benchmark. The results showed that "type faces in common use do not differ significantly" (Tinker, 1963, p. 48). The other three were chosen in order to be "radically different" (p. 46): Kabel Light, a sans serif typeface; American Typewriter, a slab serif typeface that imitated typewriting; and Cloister Black, an elaborate serif typeface. Both American Typewriter and Cloister Black were read significantly more slowly than Scotch Roman, but Kabel Light was not. Tinker concluded: "Type faces in common use are equally legible.... A serifless type, Kabel Light, is read as rapidly as ordinary type" (p. 64). In other words, Tinker (1963) did *not* show that serif typefaces were superior to sans serif typefaces. Indeed, in a subsequent annotated bibliography, Tinker (1966, p. 84) strengthened his conclusion in the light of research findings since the study by Paterson and Tinker (1932): "Typefaces in common use are equally legible. This includes the typefaces with serifs and those without serifs."

Second, in addition to the study by Arditi and Cho (2005) that was mentioned in Sect. 5.1 and involved the presentation of "scrambled" text, these researchers carried out an experiment where they asked just four participants to read aloud individual sentences. The sentences were presented one word at a time on a computer screen. Arditi and Cho found no difference in performance between sentences in a slab serif typeface and sentences in a sans serif typeface. It should be noted that they did not make use of "long texts". However, the main point is that, once again, Arditi and Cho did *not* show that serif typefaces were superior to sans serif typefaces.

Third, the review by Russell-Minda et al. (2007) on the legibility of typefaces for readers with visual impairment covered both research on reading from paper and research on reading from screens. They did indeed conclude: "Sans serif typefaces, such as Arial, Helvetica, Verdana, or Adsans, are more readable than is Times New Roman, for example" (p. 413). However, this was not supported by the evidence that they described: they cited eight studies, of which six had found no significant difference in legibility between serif and sans serif typefaces. In fact, their abstract stated, "Research has not produced consistent findings" (p. 402). Moreover, in the original report on which their published review was based, Russell-Minda et al. (2006) had arrived at a very different conclusion: "Based on results from existing studies, the effects of the presence or absence of serifs on text legibility seem to be inconclusive" (p. 23). In short, they definitely did *not* demonstrate that sans serif typefaces were superior for people living with certain disabilities.

In other words, each of these three reference citations is in error because it fails to support the statement to which it is attached. In the bibliographic research literature, these are referred to as "quotation errors", although they include indirect quotations, paraphrases, and summaries as well as direct quotations. Mertens and Baethge (2011) demonstrated that around 20% of reference citations in the medical and bioscience literature were quotation errors, but it is clearly unfortunate that such errors should occur in a document published by the American Psychological Association.

## **9.5 Conclusions**

This chapter concludes Part I by summarising and discussing the key findings. Are there any differences in the legibility of serif and sans serif typefaces when they are used to generate printed material? The modal finding from the research studies that have been reviewed is that there are not. Two studies in particular have been cited in support of the superiority of serif typefaces, but these can be discounted on scientific grounds. Are there any differences in readers' preferences and connotations between serif and sans serif typefaces when they are used to generate printed material? The modal finding is that there is no overall preference between serif and sans serif typefaces, nor any overall difference in their connotations. Even so, there is a suggestion that readers' preferences and the connotations of serif and sans serif typefaces may vary between different contexts, and the chapter discussed the implications of this for educational publishing and educational assessment.

The chapter considers the relevance of the findings for previously stated assumptions about the legibility of serif and sans serif typefaces. The traditional view that "everybody knows" that serif typefaces are easier to read on paper than sans serif typefaces is clearly untenable, since this view has never been supported by sound empirical evidence. Finally, the chapter concludes by assessing the position that is adopted in the seventh (2020) edition of the American Psychological Association's *Publication Manual*. The position confounds research on reading from paper with research on reading from computer screens, and the background paper on which it depends suffers from several quotation errors (that is, reference citations that do not support the statements to which they are attached).

**Open Access** This chapter is licensed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license and indicate if changes were made.

The images or other third party material in this chapter are included in the chapter's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the chapter's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder.

## **Part II Reading from Screens**

## **Chapter 10 "Everybody Knows": Reading from Screens**

## **10.1 Introduction**

The last 60 years have seen fundamental changes in the way that people acquire and share information. At the beginning of this period, information was mainly represented in the form of written text that was either read directly by readers themselves or else communicated by teachers or other speakers. Nowadays, much information is available on computer monitors or other screens. (One should, of course, recognise the "digital divide" both between people in the developed world and people in the developing world and also among diverse groups within the developed world in terms of their access to the relevant technologies.) The availability of this technology is particularly apparent in educational settings, where students routinely expect to acquire information through computer systems and also use such systems to submit their academic assignments to be evaluated by their teachers and other assessors.

Users of screen-based material have a choice in how they make use of that material. They can either read it in the form in which it is presented, or they can print it in hard copy. Shaikh (2004; Shaikh & Chaparro, 2004) carried out an online survey concerning reading habits and obtained responses from 330 participants: 120 were students, and the rest were recruited from a variety of e-mail lists. Most respondents were happy to read news items, newsletters, and product information online, but they preferred to scan articles in journals online before printing them off to read in more detail. This was consistent with the findings of previous studies that researchers and other professionals tended to print off articles or other important documents to read.

It used to be popular to assume that the increased use of digital technologies among young adults meant that they constituted a distinct population who thought and learned in qualitatively different ways from older people. They were variously called "Millenials" (Strauss & Howe, 1991), the "Net Generation" (Tapscott, 1998), "Digital Natives" (Prensky, 2001), and "Generation Y" (Jorgensen, 2003). However, these ideas were not supported by research evidence (see, e.g., Pedró, 2009). Surveys found *quantitative* differences between older and younger people in their attitudes to technology and their uses of technology, but there was no evidence for any *qualitative* differences in people born since the early 1980s (e.g., Jelfs & Richardson, 2013). In fact, many of today's students retain a strong preference for print (Baron et al., 2017; Mizrachi, 2015), although some do not (Singer & Alexander, 2017). (This may well depend on mundane factors such as local printing costs.)

Which typefaces should be used in the presentation of text on computer screens? One approach was to employ versions of typefaces that were already well established in conventional printing. The top row of Fig. 10.1 contains two examples of such typefaces. As was mentioned in Sect. 1.2, the serif typeface Times New Roman was devised in 1932 for use in the London newspaper *The Times*. Versions became popular in printing and publishing more generally, and in the 1980s these were provided by Macintosh and Microsoft in their word-processing software. The typeface known as "Times Roman" was adopted by Apple. The sans serif typeface Arial was devised in 1982 for use on IBM printers. It was adopted by Microsoft in 1990, and it was the default typeface for several years in some of its applications; it is also available for Macintosh users.

An alternative approach was to devise new typefaces, often with the aim of ensuring their legibility on small or low-resolution screens. The bottom row of Fig. 10.1 contains two examples of such typefaces. The serif typeface Georgia and the sans serif typeface Verdana were both developed for Microsoft in the 1990s and were released in 1996. They were subsequently made available for installation on Macintosh computers. Other researchers developed entire families of typefaces. In the United States, Bigelow and Holmes (1986) devised the Lucida family, while in Russia Paratype was devised for material in both Latin and Cyrillic text (Akhmadeeva et al., 2012). Other artificial typefaces were devised by Arditi (2004), Beier and Larson (2010), and Sanocki (1987), although some of these were so radically different from traditional typefaces that they might well have caused difficulties even for experienced readers.

It was mentioned in Sect. 5.1 that actual serif and sans serif typefaces typically differ in a number of characteristics. In principle, it should be possible to devise artificial typefaces in which serif and sans serif differ only in the presence or absence of serifs. In fact, efforts to devise such typefaces disclosed a major confound with the width of the letters and the inter-letter spacing. In particular, Arditi and Cho (2005) found that adding serifs to Arditi's (2004) sans serif style led to an increase in the mean width of the letters in order to accommodate the serifs. Conversely, Moret-Tatay and Perea (2011) found that removing the serifs from the serif style Lucida

**Fig. 10.1** Examples of common serif typefaces (Times New Roman and Georgia) and common sans serif typefaces (Arial and Verdana) for displaying text on screens

Bright led to an increase in the average inter-letter spacing. This confounding means that any results that are obtained using such typefaces are likely to be ambiguous.

In conventional paper-based printing, individual letters and other symbols are discrete physical entities. As was mentioned in Sect. 2.4, the overall height of typefaces (their *body size*) is traditionally expressed in terms of points, where one point is approximately equal to 0.35 mm. However, the size of typefaces is also expressed in terms of the dimensions of lowercase letters. The *x-height* of a typeface is the height of lowercase letters that do not have either ascenders or descenders (such as the letter *x* itself). When the same characters are presented on computer screens, they are simply fragmented digitised representations. Body size and x-height become relative terms since they depend on the size in which the characters are displayed on-screen. Rendering printed typefaces as digitised letter forms has been an exceedingly complex process involving complex debates and decisions (Bigelow, 2020a, b), although much of this process may well not be apparent to most display-screen users.

Section 2.5 argued that there was no reason to think that serifs and other features had the same consequences when people were reading from paper as when they were reading from computer monitors or other screens. In fact, with regard to reading from computer screens, designers and design educators have typically claimed that the legibility of sans serif typefaces was superior to that of serif typefaces (e.g., Poncelet & Proctor, 1993; Schriver, 1997, p. 508; "Universal Design", 1999, p. 5), hence my colleague's assertion, mentioned in Sect. 1.1, that "everybody knew" that sans serif typefaces were easier to read on screens than were serif typefaces. Even so, advocates of this position have usually failed to present any empirical evidence in support of this claim, and accordingly Part II of this book reviews the research literature with regard to the legibility of serif typefaces and sans serif typefaces when they are used to generate material on computer monitors and other screens.

## **10.2 Legibility of Serif and Sans Serif Typefaces Using Older Technology**

Before considering the legibility of typefaces using modern computers, it should be acknowledged that the use of technology to enable information to be presented in other ways than as material printed on paper is by no means a new phenomenon. From the eighteenth century onwards, speakers used epidiascopes (opaque projectors also known as episcopes) and "magic lanterns" (using transparent plates) to project images of objects and other material onto viewing screens for potentially large audiences. However, from the 1950s these were superseded by overhead projectors and slide projectors. The widespread adoption of the latter technologies led to the development of recommendations for best practice. It was widely asserted, in particular, that sans serif styles rather than serif styles should be used for the projection of textual material. Nevertheless, as Phillips (1976, pp. 18–19) observed, such assertions seem to have been based on personal preferences rather than empirical research.

Adams et al. (1965) compared the legibility of different typefaces in the images produced by an overhead projector. They tested 120 children in Grades 1, 2, 3, 5, and 6 (i.e., aged 6–12) of a university's laboratory school. The children in each grade rotated among five rows of seats at varying distances from the projection screen. They were shown groups of four uppercase letters produced on an electric typewriter in five different styles and sizes and were asked to list them on a prepared response form. For one style, the letters were in a sans serif typeface (Bulletin). For the other four styles, they were produced in different sizes in a serif typeface (Elite). One of these styles, Elite 6/32 in. (4.76 mm), was the same size as the Bulletin type. Adams et al. noted that letters in the Elite 6/32 in. style were significantly more likely to be reported correctly than were letters in the Bulletin style by children in four of the five grades. Even so, they added that this "may be a phenomenon of the sample and might not similarly be observed in a replication of the study" (p. 427).

Grooters (1972) carried out a similar study in which rows of ten uppercase letters were presented to 60 adult participants in four different sizes at four different distances by means of a Kodak Carousel slide projector. Instead of actual typefaces, he employed the templates that were in use at the time for lettering in technical drawing. The participants were required to read the letters aloud as if in an eye examination. He found that the sans serif style LeRoy Standard was marginally more legible than the slab serif style LeRoy Stymie Medium, but that both of these were significantly more legible than the sans serif style LeRoy Condensed Gothic, in which the letters were 60% of the width of those in LeRoy Standard. These results were found at all distances and in all sizes, except for the closest distance and the largest size where performance approached 100% for all three styles (in other words, there were ceiling effects).

Phillips (1976) similarly compared a slab serif style of lettering (Leroy Stymie) with a sans serif style (Twentieth Century). Using a Kodak Carousel projector, he presented 31 volunteers with six slides, each containing five lines of ten randomly ordered uppercase letters in decreasing size. Three slides contained letters printed in the slab serif style, and three contained letters printed in the sans serif style, in each case using a light, medium, or bold stroke width. Once again, the participants were asked to read the letters in each slide aloud, line by line. Overall, performance was better with the slab serif style than with the sans serif style (pp. 53–54). There was however a significant interaction between the effects of letter style and letter size, such that the difference between the two styles was only significant using one of the smaller letter sizes (pp. 56–57). There was also a significant three-way interaction with stroke width, such that the difference between the two styles was only significant for two of the 15 combinations of size and stroke width (pp. 59–60). Phillips concluded that performance was so poor with the smaller letter sizes that neither style would be acceptable for projected visual materials; but that conversely performance was so good using either style with the larger letter sizes that both serif and sans serif lettering would be acceptable for projected visual materials (p. 70).

Woods et al. (2005) showed pairs of lowercase letters to groups of children from kindergarten to fourth grade using a tachistoscope attached to a slide projector. The children had to say whether the letters in each pair were the same or different and to write them down. Each pair was presented in a serif typeface (Times New Roman) or in a sans serif typeface (Arial), and the two typefaces were presented either in separate blocks of slides or in the same block. The children's scores on both discrimination and identification were higher for letters that were presented in the sans serif typeface than for those presented in the serif typeface. This was true regardless of the children's age or the size of the typeface used. One problem with this study is that the children were tested in small groups, and some cheating had taken place.

Overhead projectors and slide projectors have in turn been superseded by computer-based projection software, most obviously by Microsoft PowerPoint. (This was developed in the 1980s by an independent software company to produce both overhead transparencies and slides. However, the company was acquired by Microsoft in 1987, and it was then developed to display presentations through digital projectors on both Windows and Macintosh systems.) PowerPoint has been in general use since the early 1990s, and in practice its applications in education and in other fields have tended to borrow techniques adopted with the older technology of slide projectors. In particular, presenters are still being advised to use sans serif typefaces rather than serif typefaces in their PowerPoint presentations (e.g., Garon, 1999). More recently, Ing et al. (2017) found that 14 out of 17 speakers at an ophthalmology conference had used sans serif typefaces in their presentations. They suggested that "serif fonts may be harder to read in digital slides" (p. 172). Phillips' (1976) suggestion that such advice is based more upon personal preference than upon empirical research probably still applies, but one study has evaluated this directly.

Earnest (2003) compared the legibility of serif and sans serif typefaces for material presented using PowerPoint. He assigned 138 students to five different groups. Four groups viewed a recording of a speech given by their university's president incorporating a slide presentation, whereas the fifth group only viewed the speech. Two of the first four groups viewed slides using a serif typeface (Times New Roman), and the other two groups viewed slides using a sans serif typeface (Verdana). Immediately afterwards, the students answered nine multiple-choice questions on factual points mentioned in the speech. Nine days later, they were asked to complete the test for a second time. Earnest found that the groups who had viewed slides obtained higher scores than the group who had only viewed the speech. However, there were no significant differences between the groups who had viewed the slides in a serif typeface and the groups who had viewed the slides in a sans serif typeface.

The limited number of studies using these older technologies have failed to produce unequivocal evidence favouring either serif or sans serif typefaces. Consistent with this idea, participants tend to give similar qualitative ratings of serif and sans serif typefaces presented using either slide projectors (Kastl & Child, 1968) or PowerPoint (Mackiewicz, 2007). There is certainly no support for the notion that sans serif styles should be routinely preferred for the projection of textual material.

## **10.3 Issues with Screen Technology**

Early computers typically lacked the facility for generating visual displays; instead, they produced text that was generated using rudimentary printers. In the 1960s, however, it was realised that visual displays might be useful, and appropriate technology was at hand to facilitate this in the form of cathode-ray tubes (CRTs), which were widely used in scientific research (as oscilloscopes) and most obviously in television sets. In CRTs, an electron gun stimulates pixels arranged in a checkerboard pattern on a phosphorescent screen, and this process is carried out repeatedly in a systematic manner to generate a visible display. Early monitors tended to be very low resolution, meaning that the details of images were lost. Indeed, this is probably the origin of the idea that sans serif typefaces should be used, because serifs would have been among the lost details. Schriver (1997, p. 403) noted that designers for television had mainly used sans serif typefaces for many years (see also McVey, 1985). Even so, technology improved, and by the year 2000 high-resolution colour CRT monitors had been developed.

In the 1990s, however, an alternative form of technology became available through liquid crystal displays (LCDs). These use liquid crystals to modulate the light emitted from a background to generate images on a computer screen, again using a checkerboard pattern of pixels that is repeatedly scanned. LCD monitors were initially developed for use with laptop computers because of their reduced size, weight, and power consumption; however, during the 2000s they became available more generally, and their resolution typically exceeded that of CRT monitors. As a result, since the late 2000s LCD monitors have generally superseded CRT monitors in computer-based applications.

One issue with the presentation of text using both CRTs and LCDs is that of aliasing. In general terms, this is the under-sampling of the information needed to produce an accurate reproduction of a particular character. More specifically, in both CRT and LCD technology, text is displayed in the form of arrays of square pixels. If a stroke in a character is oblique rather than horizontal or vertical, its contour will receive only an approximate representation as an array of pixels. As a result, it will appear irregular and ragged rather than continuous (an effect sometimes known as "staircasing" or "the jaggies"). In theory, such "aliased" text should be less legible than text printed on paper, and the effect should be more pronounced with low-resolution monitors than with high-resolution monitors.

This issue was originally handled by means of anti-aliasing software. This smoothed the edges of characters by averaging the surrounding pixels to yield varying levels of grey scale in the contours of the displayed text. Gould et al. (1987) found that text presented on paper was read significantly faster than aliased text presented in the same typeface on a CRT; however, the difference became nonsignificant when text presented on paper was compared with anti-aliased text presented in the same typeface. An analogous process known as "scale-to-grey" was used when displaying images scanned from printed text on computer monitors. Sheedy and McCarthy (1994) found that scale-to-grey led to enhanced reading performance compared to simple black-and-white text, and participants reported fewer symptoms of eye strain as a result of reading scale-to-grey text; as expected, both differences were greater with low-resolution CRTs than with high-resolution CRTs.

The increasing use of LCDs in the 1990s enabled a different approach to be taken to the aliasing issue. In LCDs, each pixel consists of three vertical bars representing the colours red, green, and blue. In 1998, Microsoft introduced ClearType software which used sub-pixel rendering with the aim of enhancing the legibility of text presented in LCDs. However, later research using a variety of tasks failed to show an unequivocal advantage of ClearType text over aliased text (Aten et al., 2002; Dillon et al., 2004, 2006; Gugerty et al., 2004; Slattery & Rayner, 2010; Tyrrell et al., 2001). Gugerty et al. (2004) also compared ClearType text with anti-aliased text using 10-point Verdana. They found that words presented in anti-aliased text were read significantly more slowly and less accurately than words presented in ClearType or aliased text, and they argued that anti-aliasing software should not be employed with smaller type sizes.

One problem with ClearType software was that the resulting characters had coloured borders that were generally thought to be distracting for readers. Microsoft therefore offered ClearType with five levels of sub-pixel rendering that varied from greyscale with no colour filtering to a high level of colour contrast. Sheedy et al. (2008) evaluated both objective performance and subjective preference for material presented in a sans serif typeface (Verdana) with all five levels of sub-pixel rendering. They found that readers preferred a moderate level of ClearType rendering to higher levels or to greyscale, but that ClearType rendering did not improve text legibility, reading speed, or reading comfort.

Another issue with screen technology is the rate at which images are refreshed: with CRTs, too slow a refresh rate leads to flicker. Wilkins (1986) showed that flicker tended to disrupt readers' saccadic eye movements, even when the refresh rate was sufficiently high to render the flicker imperceptible. (Wilkins showed that eye movements were also disrupted when readers read a printed page that was illuminated by conventional fluorescent lighting.) With LCDs, the screen itself does not flicker, but in many models the screen is backlit using pulse width modulation. The flicker may not be perceptible, but readers' eye movements may be disrupted, and they may complain of discomfort (Brown et al., 2020; Wilkins, 2021). Thus, any findings regarding participants' eye movements obtained when reading from either CRTs or LCDs need to be interpreted with caution.

## **10.4 Conclusions**

This chapter has discussed the increased use of screen-based reading in education and in daily life generally. Readers usually have the option of printing off screen-based material to be read on paper, and this seems to be popular when researchers have to read more serious material. Both the use of computer technology and attitudes to such technology seem to vary with the user's age, but there is no support for the so-called "digital natives" hypothesis. Some existing typefaces were taken over to use in computer systems, while other typefaces were developed specifically for onscreen use. The chapter discussed the legibility of serif and sans serif typefaces when projected by means of older technology such as slide projectors, overhead projectors, and PowerPoint, but this did not show any consistent difference in their legibility. Finally, the chapter described some of the technical issues concerning the way that images are displayed using CRTs and LCDs.

**Open Access** This chapter is licensed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license and indicate if changes were made.

The images or other third party material in this chapter are included in the chapter's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the chapter's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder.

## **Chapter 11 The Legibility of Letters and Words**

## **11.1 Reading Letters and Words in Serif and Sans Serif Typefaces**

One of the earliest uses of computers in vision research was as tachistoscopes for the brief presentation of visual stimuli. One fundamental problem was that cathode-ray tubes (CRTs) suffered from the decay time or persistence of the phosphor in the individual pixels, which led to inaccurate measurements (see Hutner et al., 1999). (It should be noted that traditional tachistoscopes were by no means immune to such problems: Mollon & Polden, 1978.) Liquid crystal displays (LCDs) are generally regarded as more appropriate for vision research (Wang & Nikoli´c, 2011). Even so, it is generally regarded as being good practice to use a *backward-masking* procedure in which a second stimulus or *mask* (perhaps only a random pattern) is presented after a brief interval to overwrite the visual trace of the original stimulus.

Suen and Komoda (1986) used this approach to compare the recognition of individual uppercase and lowercase letters that had been digitised using an optical scanner from print in a slab serif typeface (Courier), a sans serif typeface (Letter Gothic), and the output of a dot-matrix printer. All three typefaces were monospaced or nonproportional (that is, each character occupied the same width). The characters were presented on a high-resolution CRT screen controlled by an Apple microcomputer. (The actual duration of the presentation was not specified.) They were followed by a mask after 0 ms, 16.7 ms, or 33.3 ms. If the mask was presented immediately after the letters, performance was best with the sans serif typeface and worst with the dotmatrix style. The differences among the three styles were much reduced if the mask was presented after a delay, but this may have been a ceiling effect, since performance was 80% or better with all three styles, presumably because of the additional time available for processing the letters.

As mentioned in Sect. 4.1, Korean is another language where the alphabet can be rendered in either serif (or Ming) typefaces or sans serif (or Gothic) typefaces. Hwang et al. (1997) presented Korean participants with CRT screens consisting of 12 windows, each containing letters in one of six different sizes. The participants' task was to find and read aloud a particular target letter and then to report how much visual fatigue they had experienced while carrying out the task. The letters were presented using either an unspecified Ming typeface or an unspecified Gothic typeface. The participants' response times were faster, their accuracy was higher, and their reported visual fatigue was lower when reading letters in a sans serif typeface than when reading letters in a serif typeface. Even so, different results were obtained by Kong et al. (2011) in a study that was described in Sect. 4.1. They asked Korean participants to read aloud sets of four one- or two-syllable letters of varying sizes and to rate how much discomfort they had experienced when reading each set. The letters were presented either on paper or on an LCD screen using either an unspecified Ming typeface or an unspecified Gothic typeface. When the letters were presented on an LCD screen, there was no difference between the serif typeface and the sans serif typeface either in the participants' performance or in their reported discomfort.

As was mentioned in Sect. 5.1, Arditi (2004) devised software to generate typefaces with slab serifs of varying size. Arditi and Cho (2005) used this software to construct lowercase typefaces of uniform thickness with slab serifs extending 0% (sans serif), 5%, or 10% of the cap height (the height of capital or uppercase letters). In theory, the resulting typefaces should have varied only in the size of the serifs, but, as was mentioned in Sect. 10.1, Arditi and Cho found that an increase in the spacing between successive letters had been required to accommodate the serifs. They therefore used an inter-letter spacing of 0%, 10%, or 40% of the cap height, yielding a 3 × 3 design. Arditi and Cho measured size thresholds when random five-letter strings were presented on a CRT computer screen as black letters against a white background. Data were obtained from four participants with normal vision. There was a large effect of spacing such that closely spaced letters yielded higher thresholds (i.e., poorer performance). There was also a significant but small effect of serif size, such that serifs of 5% or 10% led to lower thresholds (i.e., better performance) than a sans serif typeface, which Arditi and Cho ascribed to the concomitant increase in spacing required to accommodate them.

After Microsoft introduced ClearType software with the aim of tackling the aliasing issue in text presented on LCDs (see Sect. 10.3), a range of new typefaces was commissioned to try to exploit this new technology. They included two serif typefaces (Cambria and Constantia) and four sans serif typefaces (Calibri, Candara, Corbel, and Consolas, the last for use mainly in programming). Chaparro et al. (2006a, b, 2010) evaluated the legibility of these new typefaces in comparison with that of the serif typeface Times New Roman and the sans serif typeface Verdana. Nine participants were presented with individual characters from all eight typefaces for just 34 ms each (but with no backward mask) using an LCD monitor with ClearType software enabled and were asked to say each character's name aloud. The proportion of characters reported correctly was highest for Consolas, Cambria, and Verdana and lowest for Times New Roman, Candara, and Corbel. Taking Times New Roman as the reference, accuracy was significantly better for Consolas, Cambria, and Verdana but not for the other four typefaces (Chaparro et al., 2010). Despite these somewhat ambivalent findings, Microsoft made Calibri the default typeface for all its Office applications in 2007 (and it remains the default at the time of writing).

Moret-Tatay and Perea (2011) used a lexical decision task in which Spanish students had to say whether or not stimuli were genuine words. Half the stimuli were Spanish words, and the other half were nonwords created by changing two letters in genuine Spanish words. Each was presented in the centre of an LCD screen in either a serif typeface (Lucida Bright) or a sans serif typeface (Lucida Sans). Once again, the typefaces should have differed only in the presence or absence of serifs, but, as mentioned in Sect. 10.1, Moret-Tatay and Perea noted that the serifs had occupied some of the space between the letters, and so removing the serifs led to a slight *increase* in the inter-letter spacing. They found that participants responded significantly more quickly to words presented in a sans serif typeface than to words presented in a serif typeface, and they suggested that this might have been due to the slight increase in inter-letter spacing.

## **11.2 The "Stripiness" of Words Displayed on Screens**

Section 4.2 described research by Wilkins et al. (2007) which measured the vertical "stripiness" of a word by the height of the first peak of the autocorrelation between an image of the word and a second, horizontally displaced image of the same word. They had found that words with a higher first peak (i.e., more stripy words) were read more slowly than words with a lower first peak (i.e., less stripy words). However, it was not clear whether this led to variations in how quickly words in different typefaces were read.

Liversedge et al. (2006) had displayed sentences to 15 students as white letters on a black background using a CRT screen and monitored the movements of both their eyes. They found that in normal binocular reading the two eyes were often misaligned after a saccade, so that part of the duration of the subsequent fixation was taken up correcting this disparity in order to achieve binocular vergence. Jainta et al. (2010) presented 32 German participants with 120 unrelated sentences in blocks of 10 to read silently from a CRT screen. They found that the participants achieved better binocular vergence when the sentences contained words with a higher first peak, but that this took longer to achieve and led to a longer overall fixation duration. They argued that these findings explained the longer overall reading time for words with higher first peaks.

Wilkins et al. (2020) observed that different typefaces appeared to vary in the periodicity of their letters' vertical strokes. In two serif typefaces, Times and Palatino, the letter strokes were relatively evenly spaced, whereas in two sans serif typefaces, Arial and Verdana, the spaces between the strokes within a letter were greater than the spaces between the letters, leading to low periodicity. Wilkins et al. determined the first peak of the horizontal autocorrelation for passages from two novels when they were printed to the Retina (LCD) screen of an Apple Macbook Pro in each of nine serif typefaces and in each of 11 sans serif typefaces. They found that the first peak of the horizontal autocorrelation was significantly greater for the serif typefaces than for the sans serif typefaces. Wilkins et al. argued that this difference in the first peak of the horizontal autocorrelation was not due to the serifs themselves but to the effect of the serifs on the rhythm or periodicity of the typefaces. However, Wilkins et al. did not provide any evidence that these differences led to significant variations in how quickly words in different typefaces were read.

## **11.3 Confusions Among Letters in Serif and Sans Serif Typefaces**

In their original study involving the presentation of uppercase and lowercase letters in either a slab serif typeface or a sans serif typeface (mentioned in Sect. 11.1), Suen and Komoda (1986) observed that with both typefaces errors often consisted of confusions between uppercase and lowercase forms of the same letter or confusions between letters that were visually similar in the same case. The total number of confusions was similar in the two typefaces, but there were certain differences in the pattern of confusions. For instance, with the sans serif typeface, lowercase letters tended to be mistaken as their uppercase counterparts rather than vice versa, but the reverse tended to be true for the slab serif typeface. Suen and Komoda ascribed these trends to the design of the characters in the relevant typefaces rather than to the presence or absence of serifs.

Using a laptop computer with an LCD screen, D. Fox, Chaparro, and Merkle (2007) presented individual characters (the 26 lowercase letters plus the digits 0–9 and 11 common mathematical and scientific symbols) to ten participants in ClearType rendering for just 34 ms (but with no backward mask) in each of 20 different typefaces. The participants were asked to say each character aloud and were scored on their accuracy. Fox et al. focused on errors for the letter *e* (which is confusable with the letter *c* and the number *0*) and for the number *0* (which is confusable with the letters *e* and *o*). For the letter *e*, the most accurate performance was obtained with the sans serif typefaces Clearview Text and Verdana, and the least accurate performance was obtained with the serif typeface Garamond. For the number *0*, the most accurate performance was obtained with the serif typefaces Centaur and Rockwell, and the least accurate performance was obtained with the serif typeface Constantia.

In further results from this study, Fox et al. (2008) compared the data for the numbers *0* and *1* (which is confusable with the letter *l*). For the number *1*, the most accurate performance was obtained with the sans serif typeface ClearView Text, and the least accurate performance was obtained with the serif typeface Centaur. Fox et al. employed classification tree analysis to identify the physical features of different typefaces that might be responsible for variations in legibility for both numbers, although they did not include the presence or absence of serifs as a feature in these analyses. Taken together, the findings of this study suggest that some characters tend to be more legible when presented on-screen in sans serif typefaces than when presented on-screen in serif typefaces, whereas the opposite is true for some other characters.

Beier and Larson (2010) constructed three new artificial typefaces. In each case, they varied the presence or absence of slab serifs with no other changes to the letters themselves. In a pre-test, each of 34 participants viewed the letter *d* presented on the LCD screen of a laptop computer that had been placed on a podium at eye-level height at a distance of 10 m. They approached the podium until they could correctly identify the letter. The relevant distance was then used for the presentation of individual uppercase and lowercase letters in the main experiment. Beier and Larson found that serifs could serve either to enhance or to impair the relative differentiation of individual letters. For instance, a slab serif added to the top of the stem of the letter *i* led to improved identification, but this was not the case when slab serifs were added to both the top of the stem and the baseline. In Sect. 4.2, it was noted that similar findings had been obtained with the identification of individual characters when reading from print (Harris, 1973; Tinker, 1963, p. 36). However, Vernon's (1929) findings, again based on reading from print, imply that such confusions would be much less likely if letters were presented in the context of meaningful text, as in normal reading.

## **11.4 Conclusions**

As with reading from print, the earliest research on the legibility of different typefaces when reading from screens was concerned with recognising individual letters and words under different conditions. Studies that employed authentic typefaces showed at most that *some* sans serif typefaces are more legible than *some* serif typefaces. Research using artificial typefaces suffers from confounding between (a) the presence or absence of serifs and (b) variations in the width of the letters and the spacing among successive letters. The horizontal autocorrelation of individual words differs across different typefaces, but it is not clear whether this leads to differences in how quickly different typefaces can be read. The vertical stripiness of serif typefaces tends to be greater than that of sans serif typefaces, but there is little evidence that this leads to variations in how quickly words in different typefaces are read. As with printed letters and words, identification errors are often the result of confusions among visually similar letters, but visual confusions are not more likely with sans serif typefaces than with serif typefaces, contradicting an old hypothesis that serifs make letters easier to discriminate (Legros, 1922, p. 11).

**Open Access** This chapter is licensed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license and indicate if changes were made.

The images or other third party material in this chapter are included in the chapter's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the chapter's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder.

## **Chapter 12 Reading and Comprehending Text**

## **12.1 Reading Text in Serif and Sans Serif Typefaces**

The work by Gould et al. (1987) was mentioned in Sect. 10.3. In another experiment, Gould et al. followed a number of previous studies comparing screen and paper presentation in a proof-reading task: 18 research workers read through articles of about 1,000 words to try to locate between 1 and 10 misspelled words by saying them aloud to the experimenter. The screen versions were presented as antialiased characters on a cathode-ray tube (CRT) screen using a system which had been specifically designed to simulate their appearance on paper, and high-quality printed versions were generated using the same script files. The screen and paper versions of each article were both presented using a serif typeface (Press) and two sans serif typefaces (Letter Gothic and Univers). Each participant read one article on-screen and one article on paper in each of the three typefaces. Overall, the paper versions were read significantly faster than the screen versions, although this might have been partly because the screen system required 1.5 s scrolling time to go from one page of text to the next. There was no significant difference in the participants' accuracy between the two versions. There was no significant variation across the typefaces and no significant interaction between the effects of display mode and typeface in either speed or accuracy.

Also using a CRT screen, Tullis et al. (1995) compared the legibility of four typefaces available in the Microsoft (MS) Windows operating environment: two serif typefaces, MS Serif and Small Font, and two sans serif typefaces, Arial and MS Sans Serif. Each was used in two, three, or four different sizes, yielding 12 combinations of typeface and size. Each of these was shown in either a bold or regular style and against a white or grey background, resulting in a total of 48 conditions that were administered in a random sequence. All of the participants viewed the same paragraph of text presented in each condition and were asked to count the number of typographical errors that it contained. After they had read the paragraph, they pressed the "Enter" key and reported the number of errors using a dialogue box. Tullis et al. measured the time taken to read the paragraph and whether or not the correct number of errors had been reported. The two sans serif typefaces yielded faster reading times, higher accuracy, and higher ratings than the two serif typefaces, especially with larger type sizes.

Garcia and Caldera (1996) asked ten students to read aloud paragraphs of 30 words from a computer screen (neither the computer nor the monitor was specified). The paragraphs were presented in three different type sizes and in five different typefaces: a serif typeface (Times New Roman), three sans serif typefaces (Arial, System, and MS Sans Serif), and a cursive typeface (i.e., a typeface intended to mimic handwriting) (Lucida Casual). There was significant variation across the 15 conditions, with 10-point Arial yielding the fastest reading time. System yielded the second fastest time, but no further results were reported.

Stone et al. (1999) asked 48 female survey interviewers to read aloud 24 sets of material, each consisting of 30 random words chosen to be at the eighth-grade reading level. Half of the sets were presented in black ink on white paper, whereas the other half were presented in black type against a white background on the liquid crystal display (LCD) screen of a laptop computer to simulate the former. In both cases, each set of words was presented on a single page, and the order of the conditions was counterbalanced. The sets of words were presented in three different typefaces: a sans serif typeface (Helvetica), a serif typeface (Times Roman), and a slab serif typeface (Courier). Stone et al. found that their participants read the sets in serif typefaces faster than the sets in sans serif typeface, but there was no significant variation in the number of errors made. There was no significant difference in either reading speed or accuracy between the sets presented on paper and those presented on-screen, and neither of the interactions with the effects of typeface and mode of presentation was significant.

Josephson (2008) carried out an exploratory study of eye-movements in reading from screens. She presented six participants with four news stories of around 250 words on a high-resolution monitor, and their eye-movements were tracked using a corneal reflection system. The stories were presented in the four different typefaces shown in Fig. 10.1 in Sect. 10.1. Afterwards, the participants were asked to rate each typeface on several 10-point scales and then to say which was easiest to read and which they liked the most. The story presented in Verdana was read the fastest, followed by that presented in Times New Roman. The story presented in Times New Roman yielded the fewest fixations, whereas that presented in Verdana yielded the most. Conversely, the story presented in Verdana yielded the fewest backward movements to reread previously presented words, whereas that presented in Times New Roman yielded the most. Verdana was rated highest whereas Times New Roman was rated lowest of the four typefaces. When asked which typeface was the easiest to read, three of the participants chose Verdana, whereas none chose Times New Roman. Apart from the small number of participants, one limitation of this study was that one story was assigned to each typeface, and so differences among the typefaces were directly confounded with differences among the news stories themselves.

Banerjee and Bhattacharyya (2011) presented 40 young postgraduate researchers with 18 passages of roughly the same length on an LCD monitor. The passages were presented in one of three serif typefaces (Times New Roman, Georgia, and the slab serif Courier New) or one of three sans serif typefaces (Arial, Tahoma, and Verdana) in one of three sizes (10, 12, or 14 points). The passages were assigned at random to the 18 conditions for each participant and presented in a different random order to each participant. The time taken by the participants to read each passage was recorded, they then rated the overall ease or difficulty of reading each passage, and finally they completed a short questionnaire on the mental workload involved in reading each passage. Their eye movements were also tracked using a binocular eye movement recorder.

There was a significant interaction between the effects of typeface and type size on the participants' reading time. The effect of type size was significant for Courier New and Arial, but not for the other four typefaces. The mean reading time was significantly less for the serif typefaces than the sans serif typefaces, but only for 10-point and 14-point sizes. Courier New and Arial also yielded the fastest average reading time. Verdana in 14-point was rated as easier to read than any other combinations of typeface and size, and Arial in 14-point was rated as the second most preferred. Verdana in 14-point was also rated as having the least mental workload, followed by Arial in 14-point and Tahoma in 14-point. Courier New yielded the lowest fixation duration, followed by Verdana and Arial; Courier New also yielded the lowest total gaze duration, followed by Verdana. In contrast, Times New Roman yielded the longest fixation duration and the longest total gaze duration. However, there were no overall differences between serif and sans serif typefaces in eye movement parameters.

Perea (2013) presented 24 Spanish undergraduate students with individual sentences on a computer screen and measured their eye movements using a videobased eye-tracking device. Each sentence appeared when the participant looked at a square on the left-hand side of the screen, and the participant pressed a key when they had finished reading the sentence to themselves. To check on their comprehension, a yes/no question was presented after 20% of the sentences. (Overall, 96% of these questions were answered correctly.) The sentences were presented in four blocks of 30. Half were presented in the serif typeface Lucida, whereas half were presented in the sans serif typeface Lucida Sans. There was no significant difference in the participants' reading times, in the total number of fixations, or in the mean duration of their fixations between the serif and sans serif sentences. Perea concluded that the presence or absence of serifs did not materially affect the process of normal reading, although different results might have been obtained with longer extracts, as in Josephson's study.

## **12.2 Comprehending Text in Serif and Sans Serif Typefaces**

As with research on reading from paper (see Chap. 5), asking the participants to read continuous text provides less opportunity for researchers to impose experimental control over their reading behaviour. Some researchers have therefore focused on their participants' *comprehension* of meaningful material read from screens rather than upon its legibility per se.

Williams (1990) carried out an experiment in which 56 students read two passages on a CRT monitor and answered four comprehension questions after each passage. Each passage contained 650–700 words and filled seven screens, so that the students had to scroll down to read the complete passages. The material was presented in either a serif typeface (10-point Times Roman) or a sans serif typeface (9-point Helvetica); the use of different type sizes ensured that the typefaces were of similar x-height. The participants were randomly assigned to five different groups. Four groups saw the two passages in different typefaces, with the order of the two passages and the order of the two typefaces counterbalanced across the four groups. The fifth group saw both passages in the sans serif typeface to check for any difference in difficulty between the two passages. The monitor screen also contained a clock, and the students were asked to record the times when they started and finished reading each passage. The comprehension questions were multiple-choice with five alternatives. The fifth (control) group showed no difference in mean reading rate between the two passages. Across the other four groups, the mean reading rate was 14.75 words/min faster for the sans serif typeface than for the serif typeface, but the difference was not statistically significant.

Lenze (1991) used a personal computer to present 84 students with a brief paragraph and then asked them a question based on its content to which they would have to type a one-word answer. The paragraph was initially presented for 1 s; if the participant answered incorrectly, the paragraph was presented for 1 s longer, and this process was continued until they answered the question correctly. They were then presented with three further paragraphs in the same way. Half the participants chosen at random were shown the paragraph in a serif typeface, and the other half were shown the paragraph in a sans serif typeface. (Neither of the typefaces was specified.) Finally, all the participants were shown examples of text in both serif and sans serif typefaces and were asked which they preferred. Lenze found that there was no sign of any significant difference between the two groups of participants in the time needed to achieve comprehension of the texts, which suggested that serif typefaces and sans serif typefaces were equally effective in supporting reading comprehension. Even so, 77% of the students preferred the sans serif typeface to the serif typeface.

Boyarski et al. (1998) compared the serif typeface Georgia and the sans serif typeface Verdana, both of which had been designed for on-screen display. Sixteen university staff and graduate students read two passages from a standard reading test presented in the two typefaces in the same body size in Microsoft Word without antialiasing. The orders of the typefaces and the passages were both counterbalanced. They were allowed 1 min to read each passage and were then asked four questions to test their comprehension of the passage (each answer being scored between 0 and 3). Finally, the participants were asked to compare the two typefaces. A measure of "effective reading speed" was obtained by dividing their comprehension score by their actual reading time on each passage in order to allow for the possibility of a trade-off between speed and accuracy. Their comprehension scores were significantly higher for passages in Georgia than for passages in Verdana. Nevertheless, there was no significant difference between the two conditions either in their actual reading time or in their effective reading speed. The participants judged the passage presented in Verdana to be easier to read than the passage presented in Georgia, but there was no significant difference in their ratings of the passages' sharpness or legibility.

Hojjati and Muniandy (2014) presented 30 international students at a Malaysian university with four 200-word English texts in different typefaces. Two were presented in the serif typeface Times New Roman, and two were presented in the sans serif typeface Verdana; in each case, one text was presented single-spaced, and the other was presented double-spaced. After each text, the students were presented with questions designed to test their retention of its content. Finally, they were asked to rate the ease with which they had been able to read each text on a 6-point scale. Regardless of spacing, they found text displayed in Verdana easier to read than text displayed in Times New Roman, they read text displayed in Verdana more quickly, and they recalled more of the content of text displayed in Verdana. However, the researchers had used Amazon Kindles (which use microcapsules containing electronic "ink") rather than LCDs, and at least some of the texts did not fit completely onto the visible area of the screens (p. 167). The material had been taken from Wikipedia and other sources and had been checked by subject experts, but the texts themselves suffered from grammatical and stylistic problems. It is also not clear whether the typefaces used for different texts were counterbalanced across participants or whether each text was always presented in the same typeface.

Csilla et al. (2016) asked 74 Hungarian students to read to themselves four selfcontained excerpts from a Hungarian translation of *The Nature of Space and Time* by Hawking and Penrose (1999). The excerpts ran for four pages in the original book but had been reformatted to fit onto two pages of European A4-sized paper. Each excerpt was prepared in six different typefaces and then saved in Portable Document Format. Two excerpts were presented on paper, and two were presented on an LCD computer monitor. In each case, one excerpt was presented in a serif typeface randomly chosen from Book Antiqua, Garamond, and Times New Roman, and the other was presented in a sans serif typeface randomly chosen from Arial, Calibri, and Verdana, so that each student saw four different typefaces. The order of the four texts was randomised for each student. The students timed themselves reading each excerpt and then answered a number of questions about its content.

Csilla et al. analysed the data for each of the four excerpts separately and carried out independent-groups tests comparing (a) the participants who had read the excerpt on paper with those who had read the excerpt on-screen and (b) the participants who had read the excerpt in a serif typeface with those who had read the excerpt in a sans serif typeface. There were no significant differences in either reading time or comprehension for any of the four excerpts. It is unfortunate that Csilla et al. did not increase the statistical power of their analysis by using the data from all four excerpts and carrying out repeated-measures tests on the variables of presentation medium and typeface within the 74 participants. They also did not examine whether there was any interaction between the effects of these two variables on either reading time or comprehension.

## **12.3 Rapid Serial Visual Presentation**

The introduction of new technologies that enable images to be presented in a variety of visual forms prompted new research methods to be used for investigating reading. One such method is that of rapid serial visual presentation (RSVP), in which letters, words, or groups of words are presented one at a time at the reader's point of fixation. This method was first developed by Gilbert (1959a, b), who presented sentences containing eight words using a movie projector to each of 76 participants and asked them to write down immediately afterwards what they had seen. He found that they were much more accurate when successive pairs of words were shown at the point of fixation than when successive pairs of words were presented across the screen as if in a line of text. Gilbert concluded that the former procedure enhanced the identification of stimuli by eliminating the need for eye movements.