# An Effect of White Space on Traditional Chinese Text-Reading on Smartphones +
## 1 Introduction
### Line Spacing  
Line spacing, a kind of white spaces, refers to the distance between text lines. The size of line spacing is expressed by leading, the distance between the baselines of successive text lines. The baseline is a reference line on which the characters rest. Consequently, there is no white space span between the two successive lines when the leading is equal to a character height. Some authors define single line spacing as when the distance of empty spaces between two adjacent horizontal lines is one character high (cf. [6]). Under their definition, the leading of single line spacing is equal to two fonts high. Others denoted single line spacing as the distance of successive text baselines (cf. [6]). Under their definition, the leading of single line spacing is equal to one font high. For consistency, this study uses the line spacing defined by leading. Previous studies on English reading found that larger line spacing had an advantage on computer screens because it decreased lateral masking [7; 8; 9]. However, the findings may be not be appropriate to generalize to Chinese text. In English, an alphabetic writing system, the words are separated by spaces. On the contrary, written Chinese text is formed by strings of equally spaced symbols, not composed of letters, neither separated by spaces. In English reading, the spaces between words help demarcate the word boundary [10]. By contrast, Chinese readers depend on lexical knowledge to segment Chinese text into words [10]. Besides, Chinese characters have more structural details and are visually more complex in form than alphanumeric characters. Possibly, suggestions of alphanumeric typography could not be generalized to Chinese typography owing to the difference between alphanumeric and ideographic writing systems. Therefore, it is necessary to explore the line spacing effects of traditional Chinese characters on reading performance. Like alphanumeric typography, larger line spacing would decrease the lateral masking effect, reducing confusion in location of characters and facilitating reading performance when reading Chinese text in desktop displays [6; 11]. For example, [PERSON] and [PERSON] found that two-font leading produced faster reading speed than one-font leading and reported higher preferences for reading comfort, reading ease and low fatigue on a 15-in display [6]. [PERSON] and his colleagues also showed that two-font leading performed better than one-font leading on reading speed and correction rate when performing proofreading tasks on a desktop display [11]. Few studies explored the line spacing of Chinese text on smartphones because many people think that larger line spacing is a waste of the limited space on smartphones [12]. Despite this, [PERSON] et al. examined the differences between four leadings of Chinese text on a smartphone, including 1.125, 1.25, 1.325 and 1.5 fonts high [12]. They also found that participants preferred the larger line spacing because of higher readability, less fatigue, and more attractiveness; but they found no significant effect of line spacing on reading time [12]. However, it is not clear whether leading sizes more than two characters in height could facilitate reading performance because they did not investigate leadings over two characters high. Previous studies fixed the viewing distance in their experiments. However, users can adjust their viewing distances in real situations. Users can adjust their viewing distances to attain an optimal visual angle subtended to the retina to see the text clearly: short (near) for small character sizes; and long (far) for large character sizes. Consequently, all character sizes are legible and would not affect performance of reading Chinese text [10]. It may not be appropriate to generalize the findings to the typographic design of traditional Chinese texts on smartphones [10].