TY - JOUR
AU - Dong, Yenan
AB - Abstract In this study, we explored the effects that the font size and line spacing of simplified Chinese characters had on their readability on smartphones. One hundred and fifteen participants were recruited to complete Chinese text comprehension tasks and provide user preferences on a 5.9-inch smartphone. Nine test conditions were studied, consisting of three font sizes (10-, 12- and 14-point) and three line spacing variations (1.25-F, 1.5-F and 2-F). The results showed that both font size and line spacing significantly affect reading time, but only font size significantly affects reading accuracy; font size, line spacing and the interaction between them have significant effects on the difficulty of reading and the degree of visual fatigue. Medium and large font sizes are more comfortable to read with large line spacing, while small and medium font sizes are more attractive with large line spacing. The results provide useful information for mobile text interface design. RESEARCH HIGHLIGHTS |$\bullet $| Font size and line spacing had significant effects on reading time: the smaller the font size and line spacing were, the shorter the reading time required; |$\bullet $| Font size had significant effects on reading accuracy: the larger the font size was, the higher the accuracy achieved; |$\bullet $| Font size, line spacing and their interaction had significant effects on the difficulty of reading and the degree of visual fatigue; |$\bullet $| Medium and large font sizes with large line spacing made reading more comfortable, while medium and small font sizes with large line spacing improved visual aesthetics. 1 INTRODUCTION With the rapid development of the Internet and the advent of the mobile 5G era, mobile Internet has become a mainstream trend. The use of smartphones has become so popular that users spend much time reading on them every day. The readability of text is an important factor in the design of a mobile reading product and affects the reading experience of the user in several ways (Darroch et al., 2005). A good text layout can reduce the user’s visual fatigue, accelerate reading speed, promote understanding of the content and improve reading satisfaction to a certain extent (Bernard et al., 2003; Liu et al., 2016). According to the 44th Statistical Report on the Development of the Internet in China, published by the China Internet Network Information Center (CNNIC), by June 2019, the number of mobile Internet users in China had reached 847 million, and the proportion of Chinese Internet users using mobile phones to access the Internet had reached 99.1% (CNNIC, 2019). Because Chinese characters are composed of strokes (Huang et al., 2009) and have more structural details and more complex forms than alphanumeric characters, suggestions on the readability of alphanumeric text cannot be extended to Chinese text (Huang, 2019). There are two types of characters in Chinese—traditional Chinese characters and simplified Chinese characters. The traditional Chinese characters are generally more complex than the simplified Chinese characters. The legibility of characters with high-level complexity was significantly poorer than that of characters with low-level complexity (Liu et al., 2016). Furthermore, simplified Chinese characters are more widely used in China today. Therefore, it is necessary to study the readability of simplified Chinese fonts on mobile devices. Numerous studies have been conducted to investigate the readability of Chinese text on computer screens. Many factors have been found to influence the readability of computer-displayed text, including the font size (Chan and Lee, 2005; Chan and Ng, 2012; Hsiao et al., 2019; Hu et al., 2016; Liu et al., 2016; Yen et al., 2011), font style (Cai et al., 2001; Chan and Lee, 2005; Chan and Ng, 2012; Yen et al., 2011), line spacing (Huang, 2017; Chan and Lee, 2005), font spacing (Hu et al., 2016; Yen et al., 2011), number of characters per line and number of menu items (Hsiao et al., 2019), stroke width and character complexity (Cai et al., 2001; Liu et al., 2016), text direction and copy placement (Chan and Ng, 2012) and display polarity (Chan and Lee, 2005). However, reading on desktop computer screens is quite different from reading on handheld computer screens (Darroch et al., 2005; Karkkainen and Laarni, 2002) and smartphone screens (Huang, 2019). The monitor of a mobile device is much smaller than that of a computer, which consequently makes large fonts unsuitable for mobile devices (Huang et al., 2009). Moreover, users can adjust their viewing distance to get the best view on mobile devices, while most previous studies on desktop displays have limited the viewing distance to a fixed amount for reading tasks (Huang, 2019). Some studies have focused on the readability of Chinese text on mobile devices. For example, Huang (2019) concluded that small characters provide a better reading performance than large ones, as the negative effect of scrolling is significant for reading on a smartphone. Huang et al. (2018) investigated the effects of white space (e.g. page spacing, paragraph spacing and line spacing) on the reading performance of Chinese essays on smartphones, and they found that an appropriate use of white space increased user performance and satisfaction in reading a traditional Chinese text. Huang et al. (2009) investigated the impacts of font size, display resolution and task type on the readability of Chinese fonts on mobile devices and suggested optimum font sizes that provide good readability for Chinese characters under four different resolutions. Wang et al. (2008) investigated the effect of different spacing on Chinese text readability on mobile phone screens for senior citizens. They found that, when the font size is 15 × 15 pixels (8 points), an inter-line spacing of 6–8 pixels and inter-character spacing of 2–4 pixels is recommended for higher text readability, lower visual fatigue and higher user preference. From the above, we can see that font size and line spacing are two important variables frequently discussed and applied to graphics and visual communication design in previous studies on reading Chinese text on mobile devices. However, few recommendations have been made for a combination of font size and line spacing of simplified Chinese characters on smartphones. Therefore, it is necessary to explore the influence of these two factors on the readability of Chinese characters and find the best combination of font size and line spacing on smartphones. The above studies mainly focus on the younger group (Cai et al., 2001; Chan and Lee, 2005; Chan & Ng, 2012; Hu et al., 2016; Huang, 2017; Huang et al., 2009; Huang, 2019; Huang et al., 2018; Liu et al., 2016; Yen et al., 2011), and the participants in these researches all had normal or corrected normal visual acuity. As college students, all participants were assumed to be understanding generally at satisfactory levels in terms of reading practice (Huang, 2017). It was ensured that their reading speed and accuracy were not limited by visual ability. Only a few studies focused on older adults (Wang et al., 2008). The majority of people with vision impairment and blindness was over the age of 50 years. With increasing age, a growing number of people suffer from visual impairments (Kim et al., 2004). Vision impairment is the most common difficulty for elders reading text (Wang et al., 2008). It may be appropriate to study an unimpaired vision group and an impaired vision group separately rather than together. In this study, we focused on university students with normal or corrected normal visual acuity. In future studies, we will consider older and visually impaired readers. 1.1 Font size In the field of alphanumeric characters readability, font size is considered to have an important impact on the readability of text on paper (Rudnicky and Kolers, 1984), desktop computers (Bernard et al., 2002; Boyarski et al., 1998; Ramadan, 2011; Tullis et al., 1995) and handheld devices (Darroch et al., 2005; Lee et al., 2008; Lee et al., 2011). It is generally believed that larger fonts have higher readability and are superior to small fonts with regard to reading speed, reading comprehension, subjective preference and visual fatigue. For example, Tullis et al. (1995) found that there were significant differences between the various font and size combinations in terms of reading speed, accuracy and subjective preferences. The most preferred fonts were Arial and MS Sans Serif at 9.75 points. Bernard et al. (2002) found that the 14-point size and the examined sans serif typefaces were perceived as being the easiest to read, fastest, most attractive and most desirable for school-related material. Bernard et al. (2003) found that text with a 12-point font size produced a significantly higher perception of subjective readability and lower difficulty in reading than text with a 10-point font size. Lee et al. (2008) stated that E-paper displays may need greater illumination (700 lx or higher) and greater character size (3.3 mm or 22 min of visual angle). Lee et al. (2011) also found that, with an increase in font size, search speed and accuracy improved significantly. Ramadan (2011) studied 10-point, 12-point and 14-point font sizes. He found that large fonts were more readable than small fonts, and the former were more preferred by readers subjectively. However, the effect of character size on text readability is more complicated. Yen et al. (2011) pointed out that the ideal character size for optimizing text readability should be large enough to be clear and readable, but small enough to hold the maximum amount of information in the same space. There have also been some studies on the effect of font size on Chinese text readability on desktop computers (Chan and Lee, 2005; Chan and Ng, 2012; Hu et al., 2016; Liu et al., 2016; Yen et al., 2011), early handheld devices (Huang et al., 2009), current tablet computers (Hsiao et al., 2019) and smartphones (Huang, 2019). For desktop computers, early handheld devices and current tablet computers, researchers found that large Chinese characters were superior to small ones in terms of reading comprehension, reading speed, preference and fatigue. For example, Chan and Lee (2005) found that large fonts were associated with better comfort and lower fatigue, and 14-point Chinese characters were significantly superior to 10-point Chinese characters. In reading tasks and visual search tasks, Huang et al. (2009) found that when the reading distance was fixed, the reading speed and search speed using large fonts were faster than those using small fonts. Hsiao et al. (2019) found that a larger character size made a significant improvement in the visual search performance over smaller character sizes across the three age groups studied. The article points out that the results of this study may not be applicable to the design of user interfaces with different screen sizes and resolutions. In another study, Huang (2019) studied 10-point, 12-point and 14-point font sizes on smaller smartphone screens and found that small fonts yielded better reading performance than large fonts, and there was no significant difference in preference ratings between different font sizes. In the study of Chinese text, most scholars have studied three font sizes: 10-point, 12-point and 14-point. In the case of a fixed reading distance, large fonts have better readability than small ones, while in the case of adjustable reading distances, small fonts provide better reading performance than large ones. 1.2 Line spacing For alphanumeric characters, line spacing refers to the distance between the falling line of one text line and the rising line of the next text line. For Chinese characters, it refers to the distance between the bottom of a line and the bottom of the next line. In previous studies, some authors have defined line spacing as the blank distance between two adjacent horizontal lines (see the left side of Fig. 1), that is, if the blank distance was the height of a font, the line spacing was expressed as 1-F leading. Conversely, some authors have defined line spacing as the distance between the baselines of the bottom of the fonts of consecutive text lines (see the right side of Fig. 1), that is, if the blank distance was one font height, the line spacing was expressed as 2-F leading (Huang et al., 2018). For consistency, the second definition of line spacing is used in this study (as on the right side of Fig. 1). FIGURE 1 Open in new tabDownload slide Line spacing definition criteria. FIGURE 1 Open in new tabDownload slide Line spacing definition criteria. Previous studies have shown that, with increased line spacing, reading speed on computers increases, because increases in vertical word spacing may reduce the adverse effects of congestion between adjacent text lines. Moreover, large line spacing yields higher reading comfort and preference and lower visual fatigue (Chan and Lee, 2005; Chung, 2004; Ling and Schaik, 2007). Dobres et al. (2018) found that larger font size and larger line spacing significantly improved legibility; however, larger line spacing could not offset the loss of legibility that occurred at smaller font sizes. Huang (2017) presented an eye tracking study of how line spacing affects simplified Chinese reading and found that 17% line spacing seemed to be easier to read and produced better comprehension than larger line spacing. The results were not concordant with the findings of Chan and Lee (2005), probably because Huang (2017) used a normal reading task, but Chan and Lee (2005) used a slow reading task. In addition to the studies on computers, researchers have also studied readability with regard to mobile devices. It has been found that font size and line spacing influence each other. The larger the line spacing is, the better the readability, the lower the fatigue and the greater the aesthetic appeal (Wang et al., 2008). However, larger line spacing results in a longer reading time (Huang et al., 2018). In addition, Huang et al. (2018) also speculated that 2-F or 1.5-F line spacing might be the optimal line spacing for Chinese text on smartphones, but further empirical studies are needed to confirm this inference. 1.3 Study hypotheses The objective of the present study was to explore whether the two factors of the font size and line spacing of Chinese text have an impact on its readability on smartphones. According to the findings from existing relevant studies (Bernard et al., 2003; Chan and Lee, 2005; Dobres et al., 2018; Huang et al., 2009; Huang, 2019), the following hypotheses were proposed. Hypothesis 1. The larger the font size and line spacing are, the longer it takes to read. Most previous studies have shown that large fonts result in better reading performance than small ones (Bernard et al., 2003; Chan and Lee, 2005; Huang et al., 2009; Ramadan, 2011). However, these studies have fixed reading distances. According to the finding of a study allowing free adjustment of the viewing distance, the larger the font was, the longer it took to read (Huang, 2019). A study on line spacing has also shown that the larger the line spacing was, the longer it took to read (Huang et al., 2018). Thus, we speculated that large font size and line spacing would cause participants to spend more time reading. Hypothesis 2. Font size and line spacing have no effect on reading accuracy. Previous studies on computers have shown that font size affects reading accuracy (Chan and Lee, 2005). On mobile devices, however, the results have shown no effect of font size on reading accuracy (Huang, 2019). Moreover, studies on line spacing have rarely discussed the factor of reading accuracy. Because line spacing and font size are both external forms of expression, we speculated that both line spacing and font size would have no effect on reading accuracy. Hypothesis 3. The larger the font size and line spacing are, the easier it is to read and the less likely to cause reading fatigue. Almost all previous studies have shown that a large font size makes it easier for participants to read. The same findings have also been true for line spacing studies (Chan and Lee, 2005; Huang et al., 2018; Wang et al., 2008). Thus, we made the same assumption. Hypothesis 4. Large font size and large line spacing are more comfortable, while small font size and medium line spacing are more aesthetically pleasing. Previous studies have shown that a large font size is more comfortable to read, and large line spacing can also improve reading comfort (Chan and Lee, 2005; Huang et al., 2018). In terms of aesthetics, due to sampling from a young group, we speculated that small font size and medium line spacing would be pleasing, based on our visual perception when reading essays in different formats. Hypothesis 5. There is an interaction between font size and line spacing, and they will affect each other. Specifically, the interaction has no effect on reading time or on reading accuracy, but it has a significant effect on subjective evaluation scores. Because Tinker (1963) found that the two would affect each other for text printed on paper, we speculated that there might also be interactions on mobile devices. In addition, based on the findings of Dobres et al. (2018) that the interaction between line spacing and font size has little effect on readability, we speculated that it would have no significant effect on reading time or on reading accuracy on smartphones. However, that study focused on a vehicle-mounted interface. In addition, combined with the findings of Tinker (1963), we speculated that the interaction of the two factors would have an impact on subjective evaluation scores. 2 EXPERIMENT This study implemented a two-factor (3 × 3) within-subjects design, with font size (i.e. 10-point, 12-point and 14-point) and line spacing (i.e. 1.25-F, 1.5-F and 2-F) serving as independent variables. The specific experimental methods were as follows. 2.1 Participants Eligible participants were identified if they reported having normal or corrected-to-normal vision and healthy upper extremity function and if they had never previously undertaken any speed-reading training. One hundred and fifteen undergraduate and graduate students were recruited from a university in the Zhejiang Province of China. These subjects consisted of 54 males and 61 females, and the mean age was 22.64 years with a standard deviation of 3.15 years. 2.2 Materials A software prototype was developed by a research assistant using the Android platform to create task scenarios. The software prototype was administered using a Huawei Mate 10 mobile phone to control the experimental program and collect experimental data. The phone is 5.9 inches in size with a resolution of 2560 × 1440 pixels. Nine essays were chosen from reading comprehension tests used in a high school in China, with the same levels of difficulty. The lengths of the nine essays, including punctuation marks, were 748, 753, 755, 750, 755, 748, 754, 752 and 748 characters. Each of the nine essays appeared once in each experimental trial, and each essay corresponded to one of nine format combinations. 2.3 Task and procedures First, participants were required to perform Chinese text comprehension tasks on a smartphone. Before the experiment began, the participants were provided with instructions on the experimental procedures. There is no fixed sight distance in this study. To simulate the real context, the subjects can adjust the visual distance at any time (Huang, 2019). The smartphone displayed a preparation page. Participants needed to click the ‘Start Experiment’ button to enter the page, and then entered the personal information page, followed by the trial reading stage, as shown in Fig. 2. The purpose of the trial reading was to help the participants become familiar with the experimental process. The data from the trial reading essay were not counted. After the trial reading phase, participants entered the formal testing phase. FIGURE 2 Open in new tabDownload slide Personal information page. FIGURE 2 Open in new tabDownload slide Personal information page. The participants clicked the ‘start reading’ button to read the nine essays in turn. After reading each essay, the participants had to evaluate the experience of reading the passage in terms of the two attributes, reading fatigue and reading difficulty (Fig. 3). Each question was answered on a 5-point Likert scale, where a higher score means easier to read and less fatigue. Subsequently, three reading comprehension questions were completed, with questions involving the storyline, the theme and main idea of the essay. The system recorded the time the participants spent reading the essay and the correct rate of reading comprehension. To avoid fatigue, each essay was followed by a 1-minute break, during which the smartphone screen appeared black. FIGURE 3 Open in new tabDownload slide Essay page and answer page. FIGURE 3 Open in new tabDownload slide Essay page and answer page. FIGURE 4 Open in new tabDownload slide Mean reading times influenced by line spacing combined with font size. FIGURE 4 Open in new tabDownload slide Mean reading times influenced by line spacing combined with font size. Finally, the participants had to evaluate all the formats: they were asked to choose their three favourite design formats from the perspectives of comfort and aesthetics. In our study, the good and comfort feeling of the eyes means a comfortable user experience with a clear and legible vision when reading text on mobile devices. Aesthetics can be defined as visual appeal or sensual attractiveness (Lindgaard and Dudek, 2003). The essay format could be reviewed by clicking the corresponding number on the page. After the forms were completed, the end page appeared, and the experiment terminated. 3 RESULTS After the experiment, the data were sorted, and a total of 115 sets of data were obtained. After accounting for implausible reading times and particularly low accuracy rates of reading comprehension, there remained 96 valid data sets, with 19 invalid data sets having been eliminated. This section contains the outcomes of the gathered subjects’ reading performance and subjective preferences. First, basic descriptive statistics are demonstrated and described. Then, analysis of variance (ANOVA) and Duncan’s multiple comparison method were used to evaluate the impacts of font size and line spacing on the readability of the simplified Chinese fonts on smartphones. The results were as follows. 3.1 Reading time Figure 4 shows that the reading time increased as font size and space increased. The descriptive statistics indicated that the observed differences may be significant. To formally verify the significance of the differences between the examined factors, a two-way ANOVA, (font size) × (line spacing), was applied. The results of the ANOVA are shown in Table 1. TABLE 1 Variance analysis of reading time (seconds). Source of variation . Sum of squares . df . Mean square . F . P . Character size 16874.030 2 8437.015 14.493 0.000 Line spacing 11342.322 2 5671.161 9.742 0.000 Character size * line spacing 1066.657 4 266.664 0.458 0.767 Error 497741.406 855 582.154 Total 4109751.000 864 Source of variation . Sum of squares . df . Mean square . F . P . Character size 16874.030 2 8437.015 14.493 0.000 Line spacing 11342.322 2 5671.161 9.742 0.000 Character size * line spacing 1066.657 4 266.664 0.458 0.767 Error 497741.406 855 582.154 Total 4109751.000 864 Open in new tab TABLE 1 Variance analysis of reading time (seconds). Source of variation . Sum of squares . df . Mean square . F . P . Character size 16874.030 2 8437.015 14.493 0.000 Line spacing 11342.322 2 5671.161 9.742 0.000 Character size * line spacing 1066.657 4 266.664 0.458 0.767 Error 497741.406 855 582.154 Total 4109751.000 864 Source of variation . Sum of squares . df . Mean square . F . P . Character size 16874.030 2 8437.015 14.493 0.000 Line spacing 11342.322 2 5671.161 9.742 0.000 Character size * line spacing 1066.657 4 266.664 0.458 0.767 Error 497741.406 855 582.154 Total 4109751.000 864 Open in new tab Table 1 shows that font size had a significant effect on reading time (F = 14.493, P = 0.000), and line spacing had a significant effect on reading time (F = 9.742, P = 0.000); however, the effect of the interaction between them was not significant (F = 0.458, P = 0.767). Table 2 shows the significant differences between the font size and line spacing variables. Duncan’s multiple comparisons show that essays presented with 14-point fonts were associated with the longest reading time, followed by the 12-point and the 10-point fonts. With regard to line spacing, essays presented with 2-F leading were associated with the longest reading time, followed by 1.5-F leading and 1.25-F leading. TABLE 2 Duncan’s method applied to reading times for each level of independent variable. . Level . N . Subset for alpha = 0.05 . 1 . 2 . 3 . Character size 10 points 288 58.674 12 points 288 65.076 14 points 288 69.434 Line spacing 1.25-F 288 59.806 1.5-F 288 64.715 2.0-F 288 68.663 . Level . N . Subset for alpha = 0.05 . 1 . 2 . 3 . Character size 10 points 288 58.674 12 points 288 65.076 14 points 288 69.434 Line spacing 1.25-F 288 59.806 1.5-F 288 64.715 2.0-F 288 68.663 Means for groups in homogeneous subsets are displayed. aUses harmonic mean sample size = 288.000. bα = 0.05. Open in new tab TABLE 2 Duncan’s method applied to reading times for each level of independent variable. . Level . N . Subset for alpha = 0.05 . 1 . 2 . 3 . Character size 10 points 288 58.674 12 points 288 65.076 14 points 288 69.434 Line spacing 1.25-F 288 59.806 1.5-F 288 64.715 2.0-F 288 68.663 . Level . N . Subset for alpha = 0.05 . 1 . 2 . 3 . Character size 10 points 288 58.674 12 points 288 65.076 14 points 288 69.434 Line spacing 1.25-F 288 59.806 1.5-F 288 64.715 2.0-F 288 68.663 Means for groups in homogeneous subsets are displayed. aUses harmonic mean sample size = 288.000. bα = 0.05. Open in new tab 3.2 Reading accuracy Figure 5 shows that the highest reading accuracy, as influenced by font size and line spacing together, is obtained with 14-point size and 2-F line spacing. It shows that reading accuracy was not significantly affected by different line spacing when the font sizes were 10-point and 12-point. To formally verify the significance of the differences between the examined factors, a two-way ANOVA, (font size) × (line spacing), was applied. The results are shown in Table 3. FIGURE 5 Open in new tabDownload slide Mean of reading accuracy as influenced by the combination of line spacing and font size. FIGURE 5 Open in new tabDownload slide Mean of reading accuracy as influenced by the combination of line spacing and font size. TABLE 3 Variance analysis of reading accuracy. Source of variation . Sum of squares . df . Mean square . F . P . Character size 5635.824 2 2817.912 3.053 0.048 Line spacing 4524.250 2 2262.125 2.451 0.087 Character size * line spacing 8567.646 4 2141.911 2.321 0.055 Error 789090.000 855 922.912 Total 4800913.980 864 Source of variation . Sum of squares . df . Mean square . F . P . Character size 5635.824 2 2817.912 3.053 0.048 Line spacing 4524.250 2 2262.125 2.451 0.087 Character size * line spacing 8567.646 4 2141.911 2.321 0.055 Error 789090.000 855 922.912 Total 4800913.980 864 Open in new tab TABLE 3 Variance analysis of reading accuracy. Source of variation . Sum of squares . df . Mean square . F . P . Character size 5635.824 2 2817.912 3.053 0.048 Line spacing 4524.250 2 2262.125 2.451 0.087 Character size * line spacing 8567.646 4 2141.911 2.321 0.055 Error 789090.000 855 922.912 Total 4800913.980 864 Source of variation . Sum of squares . df . Mean square . F . P . Character size 5635.824 2 2817.912 3.053 0.048 Line spacing 4524.250 2 2262.125 2.451 0.087 Character size * line spacing 8567.646 4 2141.911 2.321 0.055 Error 789090.000 855 922.912 Total 4800913.980 864 Open in new tab Table 3 shows that font size had a significant effect on reading accuracy (F = 3.053, P = 0.048), while line spacing (F = 2.451, P = 0.087) and the interaction between the two (F = 2.321, P = 0.055) had no significant effect on reading accuracy. Duncan’s multiple comparisons in Table 4 show that the reading comprehension accuracy for the 14-point font size was the highest, whereas that of the 10-point font size was the lowest. TABLE 4 Duncan’s method applied to reading accuracy for each level of independent variable. . Level . N . Subset for alpha = 0.05 . 1 . 2 . 3 . Character size 10 points 288 65.6281% 12 points 288 66.7878% 66.7878% 14 points 288 71.5319% Line spacing 1.25-F 288 65.9778% 1.5-F 288 66.7851% 2.0-F 288 71.1851% . Level . N . Subset for alpha = 0.05 . 1 . 2 . 3 . Character size 10 points 288 65.6281% 12 points 288 66.7878% 66.7878% 14 points 288 71.5319% Line spacing 1.25-F 288 65.9778% 1.5-F 288 66.7851% 2.0-F 288 71.1851% Means for groups in homogeneous subsets are displayed. aUses harmonic mean sample size = 288.000. bα = 0.05. Open in new tab TABLE 4 Duncan’s method applied to reading accuracy for each level of independent variable. . Level . N . Subset for alpha = 0.05 . 1 . 2 . 3 . Character size 10 points 288 65.6281% 12 points 288 66.7878% 66.7878% 14 points 288 71.5319% Line spacing 1.25-F 288 65.9778% 1.5-F 288 66.7851% 2.0-F 288 71.1851% . Level . N . Subset for alpha = 0.05 . 1 . 2 . 3 . Character size 10 points 288 65.6281% 12 points 288 66.7878% 66.7878% 14 points 288 71.5319% Line spacing 1.25-F 288 65.9778% 1.5-F 288 66.7851% 2.0-F 288 71.1851% Means for groups in homogeneous subsets are displayed. aUses harmonic mean sample size = 288.000. bα = 0.05. Open in new tab 3.3 Subjective evaluation scores Figure 6 shows the highest subjective evaluation score, as influenced by font size combined with line spacing, was 12-point size and 2-F leading. Under the condition of small and medium spacing, the larger the font size, the higher the evaluation scores. When the line spacing is large, the medium font size scored the highest, followed by large ones and finally small ones. To formally verify the significance of the differences between the examined factors a two-way ANOVA, (font size) × (line spacing), was again applied. The results of the ANOVA are shown in Table 5. FIGURE 6 Open in new tabDownload slide Mean of subjective evaluation scores as influenced by the combination of line spacing and font size. FIGURE 6 Open in new tabDownload slide Mean of subjective evaluation scores as influenced by the combination of line spacing and font size. Table 5 shows that font size (F = 44.318, P = 0.000), line spacing (F = 53.249, P = 0.000) and the interaction between them (F = 3.478, P = 0.008) all had significant effects on the subjective evaluation scores. Duncan’s multiple comparisons in Table 6 show that the 12-point and 14-point sizes obtained higher scores, with no significant difference between them, followed by the 10-point size. For line spacing, 2-F leading obtained the highest scores, followed by 1.5-F leading and then 1.25-F leading. In other words, small font sizes and small line spacing were more difficult to read and can easily to lead visual fatigue. TABLE 5 Variance analysis of the subjective evaluation scores. Source of variation . Sum of squares . df . Mean square . F . P . Character size 65.948 2 32.974 44.318 0.000 Line spacing 79.238 2 39.619 53.249 0.000 Character size * line spacing 10.352 4 2.588 3.478 0.008 Error 636.148 855 0.744 Total 10777.350 864 Source of variation . Sum of squares . df . Mean square . F . P . Character size 65.948 2 32.974 44.318 0.000 Line spacing 79.238 2 39.619 53.249 0.000 Character size * line spacing 10.352 4 2.588 3.478 0.008 Error 636.148 855 0.744 Total 10777.350 864 Open in new tab TABLE 5 Variance analysis of the subjective evaluation scores. Source of variation . Sum of squares . df . Mean square . F . P . Character size 65.948 2 32.974 44.318 0.000 Line spacing 79.238 2 39.619 53.249 0.000 Character size * line spacing 10.352 4 2.588 3.478 0.008 Error 636.148 855 0.744 Total 10777.350 864 Source of variation . Sum of squares . df . Mean square . F . P . Character size 65.948 2 32.974 44.318 0.000 Line spacing 79.238 2 39.619 53.249 0.000 Character size * line spacing 10.352 4 2.588 3.478 0.008 Error 636.148 855 0.744 Total 10777.350 864 Open in new tab TABLE 6 Duncan’s method applied to the subjective evaluation scores for each level of independent variable. . Level . N . Subset for alpha = 0.05 . 1 . 2 . 3 . Character size 10 points 288 3.0103 12 points 288 3.5661 14 points 288 3.6225 Line spacing 1.25-F 288 2.9906 1.5-F 288 3.4942 2.0-F 288 3.7141 . Level . N . Subset for alpha = 0.05 . 1 . 2 . 3 . Character size 10 points 288 3.0103 12 points 288 3.5661 14 points 288 3.6225 Line spacing 1.25-F 288 2.9906 1.5-F 288 3.4942 2.0-F 288 3.7141 Means for groups in homogeneous subsets are displayed. aUses harmonic mean sample size = 288.000. bα = 0.05. Open in new tab TABLE 6 Duncan’s method applied to the subjective evaluation scores for each level of independent variable. . Level . N . Subset for alpha = 0.05 . 1 . 2 . 3 . Character size 10 points 288 3.0103 12 points 288 3.5661 14 points 288 3.6225 Line spacing 1.25-F 288 2.9906 1.5-F 288 3.4942 2.0-F 288 3.7141 . Level . N . Subset for alpha = 0.05 . 1 . 2 . 3 . Character size 10 points 288 3.0103 12 points 288 3.5661 14 points 288 3.6225 Line spacing 1.25-F 288 2.9906 1.5-F 288 3.4942 2.0-F 288 3.7141 Means for groups in homogeneous subsets are displayed. aUses harmonic mean sample size = 288.000. bα = 0.05. Open in new tab FIGURE 7 Open in new tabDownload slide Comfort and aesthetics results in relation to each combination of font size and line spacing. FIGURE 7 Open in new tabDownload slide Comfort and aesthetics results in relation to each combination of font size and line spacing. 3.4 Preference on visual aesthetics and reading comfort Finally, the participants were asked to choose their three favourite design formats from the nine combinations considering comfort and aesthetics. Figure 7 shows the comfort and aesthetics results related to each combination of font size and line spacing. With the font size held constant, larger line spacing was associated with better visual aesthetics and reading comfort. With line spacing held constant, a 12-point font size is generally more popular in terms of visual aesthetics and reading comfort. Participants generally thought that the medium and large font sizes were more comfortable to read with large line spacing, while medium and small font sizes were more attractive with large line spacing. 4 DISCUSSION In this study, the effects of font size and line spacing on mobile reading are discussed. 4.1 Effects of font size In terms of reading time, we found that participants spent more time reading the larger font size. This finding, in support of Hypothesis 1, is consistent with that of Huang (2019). Both in our test and in the test by Huang (2019) participants were allowed to adjust the viewing distance at will, and reading large text required more scrolling, while other studies used a fixed viewing distance. Moreover, the users needed to adjust the reading distance in a flexible manner for the actual reading scenario using smartphones. In terms of reading accuracy, we found that font size had a significant effect. Thus, Hypothesis 2 was not supported. Reading comprehension accuracy for large fonts (14 points) was higher than that for small fonts (10 points). The reason for the difference between our findings and previous results for mobile phones might be that the reading tasks established in the previous experiments were relatively simple, while the participants were generally highly educated and had good reading comprehension skills. Therefore, the essays used in the previous test were too easy for the participants (Huang, 2019). In our study, the essays used in the experiments were all selected from high school reading comprehension tests, which have a certain degree of difficulty, and this might account for the difference in reading accuracy. Our findings are the same as those found for computers and paper (Chan and Lee, 2005). It can be inferred that large fonts could provide better readability and improve the understanding of content to a certain extent. In terms of subjective evaluation scores towards the two dimensions of reading difficulty and visual fatigue, we found font size to have a significant effect. The larger the font size was, the greater the readability and the lower the fatigue became, thereby supporting Hypothesis 3. This finding is different from that of Huang (2019), who noted no significant difference in preference ratings between different font sizes. The reason for the discrepancy may be that each participant in that study only read one of nine design combinations at random; thus, there was no cross-condition comparison among different formats. In our experiment, each participant was required to read all nine formats for the essays, evaluate each format in terms of difficulty of reading and visual fatigue and finally select their three favourite formats out of the nine, a process that might more objectively reflect the participants’ preferences for different design combinations. In terms of reading comfort and aesthetics, for the same line spacing, the 12-point font size was more popular. In addition, most participants agreed that articles with small and medium fonts (10 points and 12 points) were more aesthetically pleasing, and medium and large fonts (12 points and 14 points) were more comfortable to read. These findings partly support Hypothesis 4. Through the interviews with participants, it was found that they generally believed that small fonts had more delicate visual effects, which was more in line with the aesthetic views of a younger group. Younger individuals have a broader field of vision, better contrast sensitivity and better sensory and perceptual abilities (Wang et al., 2008). Moreover, in terms of reading comfort, they thought that the medium and large fonts were more conducive to reading and could reduce visual fatigue. 4.2 Effects of line spacing We found that line spacing had a significant effect on reading time: the larger the line spacing was, the longer the time spent reading, thereby supporting Hypothesis 1. This finding is similar to that of most other studies on line spacing on smartphones (Huang et al., 2018). However, Wang et al. (2008) found that line spacing had no significant effect on reading time. The reason their results are contrary to ours might be that the research objectives were different. They performed research on the elderly, while we did it on the young. There are differences in vision between these two groups. Due to changes in the retina and nervous system, changes in vision occur in many elderly people, including decreases in vision, contrast sensitivity and the effective field of vision (Helve and Krause, 1972; Owsley et al., 1983). Visual impairment is the most common difficulty experienced by older adults. Visual problems in reading have mostly been related to text presentation, including font size, background colour, font style and text spacing (Hanson, 2001; Hawthorn, 1998). In future studies, we can carry out Chinese readability-related studies among the elderly. In terms of reading accuracy, our findings, in partial support of Hypothesis 2, showed that line spacing had no effect on reading accuracy. In terms of difficulty of reading and visual fatigue, our study also found that line spacing had a significant effect on both these dimensions and that text with larger line spacing was easier to read and was associated with lower fatigue. This finding, in support of Hypothesis 3, was consistent with those of previous studies (Chan and Lee, 2005; Wang et al., 2008). In terms of reading comfort and aesthetics, with font size held constant, the larger the line spacing, the higher the aesthetics and comfort appeared. Smaller line spacing was the least popular in terms of aesthetics and comfort. These findings partly support Hypothesis 4. In other words, this means that although people need to spend more time reading, larger line spacing is more comfortable and attractive. In addition, Huang et al. (2018) tested 2-F and 3-F leadings but did not study 1.5-F leading. They inferred from their experimental results that 2-F leading or 1.5-F leading might be the optimal line spacing for reading Chinese text on smartphones. In our study, 1.25-F, 1.5-F and 2-F leadings were tested. Considering the effect of reading speed and subjective preferences, it was found that 1.5-F and 2-F leadings were indeed suitable for Chinese text on smartphones. 4.3 Interaction between font size and line spacing The results showed that the interaction between line spacing and font size had no significant effect on reading time nor on reading accuracy but had a significant effect on subjective evaluation scores. Thus, Hypothesis 5 is supported. In terms of reading comfort and aesthetics, participants generally agreed that it was more comfortable to match medium and large font sizes with large line spacing, and it was more aesthetically pleasing to match small and medium font sizes with large line spacing. This suggests that one cannot simply assume that a particular size is comfortable or aesthetically pleasing. Tinker (1963) found that font size and line spacing are correlated with each other for newspaper type. Our research also produced this finding. This study has certain limitations. For example, this study only explored two elements that affect the readability of simplified Chinese characters on smartphones for young adults. Future research may extend our understanding of this design space along other dimensions, such as font type, background colour, display polarity and white space. The results of this study may not be applicable to the user interface design of different smartphone screen sizes and resolutions. For the best visual experience, we recommend a further investigation to determine the relationship between resolution and size of screen and various interface elements on a smartphone. Moreover, eye-movement techniques could be applied to the studies to examine how different variables affect the readability of simplified Chinese characters. Another limitation was that the present study did not focus on different groups of people, such as older adults and visually impaired individuals, to obtain richer design guidelines and achieve personalized and customized solutions. In future studies, we will consider older and visually impaired readers by adopting diversified methods. The final result of the research will help to improve the interface design of mobile reading software. For example, the software will intelligently recommend appropriate interface collocation for different categories of users. Furthermore, the assessment about aesthetic and comfort in this study is not detailed. More analyses in depth are needed to enrich the studies in future. 5 CONCLUSION In this study, we investigated the effects of font size and line spacing on the readability of simplified Chinese fonts on smartphones. The results showed that, with the currently used screen size, font size and line spacing had significant effects on reading time. The larger the font size and line spacing, the longer the reading time. Moreover, font size had a significant effect on reading accuracy. Larger font sizes improved understanding of the content to a certain extent. Font size, line spacing and their interaction all had significant effects on the difficulty of reading and the degree of visual fatigue. The larger the font size and line spacing were, the easier it was to read and the lower was the fatigue. It was determined that, if users were pursuing comfortable reading, medium and large font sizes with large line spacing should be used. For better visual aesthetics, small and medium font sizes with large line spacing should be used. The aim of this study was to provide useful recommendations of font size and line spacing combinations for simplified Chinese characters. These results have some implications and generated useful design guidelines for the interface design of smartphones, which usually present interactions in the form of scrollable and/or selectable lists (Dobres et al., 2018). As smartphone interfaces become increasingly complex and often rely on neat lists of text, it is important to recognize the trade-offs inherent in seemingly trivial design decisions (Dobres et al., 2018). Users can read articles anywhere on their smartphone at any time; however, before reading, they need to find the available options through the user interface. Although current mobile reading software has its default design and let users adjust the font size or line spacing separately, users cannot quickly set up a combination to suit their reading needs with a single click. Because of the user’s subjectivity, adjusting settings can be time-consuming and inefficient (Soubaras, 2020). This study may help to provide actionable guidance on the functional design of formatting options. For example, designers can establish an appropriate association mechanism between font size and line spacing. When users select a font size, the mobile reading software will automatically match the appropriate line spacing to achieve the best reading effect. Also, designers can set up different reading modes (i.e. fast, accurate, comfortable, aesthetic) as factory default settings for different user groups, so the users do not need to perform any manual setup. Of course, users will be able to switch between different modes when needed. Based on the results of this study, the reading parameters and operation mode of mobile reading application interfaces can be innovatively designed; that is, the most suitable typesetting format can be recommended intelligently according to the user’s age and preferences. The font size, line spacing and other reading settings can adapt to the user’s personal characteristics and reading demands. Such a design will bring great convenience to users in the reading process, save the time of repeatedly adjusting the reading parameters, meet the personalized reading needs of users and improve the readability and reading experience. As smartphone screens develop in the future, similar research methods can be used for further research on mobile readability. Acknowledgements The authors would like to thank the participants of the current study for participation and the reviewers who provided insightful and valuable suggestions for improving this paper. References Bernard , M. L. , Chaparro , B. 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TI - Effects of the Font Size and Line Spacing of Simplified Chinese Characters on Smartphone Readability
JF - Interacting with Computers
DO - 10.1093/iwc/iwab020
DA - 2021-08-18
UR - https://www.deepdyve.com/lp/oxford-university-press/effects-of-the-font-size-and-line-spacing-of-simplified-chinese-T09T0FhPIa
SP - 1
EP - 1
VL - Advance Article
IS - 
DP - DeepDyve
ER -