Despite the fact that a large percentage of the world's population are readers of Chinese, much less is known about eye movements during reading of this logographic script in comparison to alphabetic writing systems (particularly English). Chinese text is formed by strings of equally spaced box-like symbols (called characters). Text used to be printed from top-to-bottom (with the columns printed from right-to-left) but it is now typically printed horizontally from left-to-right. However, Chinese is written without spaces between successive characters and words. Furthermore, individual Chinese characters differ considerably in complexity because they vary in (1) the number of strokes per character, (2) the number of radicals (or certain combinations of strokes that denote semantic or phonological information) and (3) the manner of construction (since radicals can be combined in different ways to form compound words). Thus, many visual details are packed into a constant, box-shaped area for each character.
Chinese characters differ in frequency of occurrence as well as in complexity. While the concept of a word is not as well defined in Chinese as it is in English (and Chinese readers often disagree concerning where word boundaries are located), as in English, some words occur more frequently than others. Most words are made up of two characters, although some words consist of only one character and some consist of three or more characters. Although it is sometimes assumed that Chinese characters are like individual words, in actuality a more accurate description is that most Chinese characters are more like morphemes.
To what extent do the eye movements of Chinese readers and readers of English differ? Obviously, there are differences that are due to the fact that the information is more densely packed in Chinese (Chen, Song, Lau, Wong, & Tang, 2003) than in English and due to the fact that there are no spaces between words. Thus, not surprisingly, the perceptual span (or region of effective vision) for Chinese readers is much smaller than that of readers of English (Chen & Tang, 1998). For Chinese readers, the span extends 1 character to the left of fixation to 2-3 characters to the right when reading from left-to-right (Inhoff & Liu, 1997, 1998); in contrast, the span extends 3-4 letters to the left of fixation to about 14-15 letters to the right of fixation for readers of English (Rayner, 1998). Given the smaller perceptual span, the average saccade size in reading Chinese is about 2.6 characters (Inhoff & Liu, 1997, 1998) compared with roughly 7-8 letters for English (Rayner, 1998).
Despite these differences in the informational density and spatial characteristics of the text, there are a number of similarities in eye movements between readers of Chinese and English. First, average fixation durations are very similar (about 225-250 ms) for readers of Chinese and English (Chen et al., 2003; Feng, Miller, Shu, & Zhang, 2001; Sun & Feng, 1999; Rayner, 2004). Second, regression rate is only slightly higher for Chinese readers, with skilled readers of Chinese regressing about 15% of the time compared with about 10% of the time for skilled readers of English (Chen et al., 2003). Third, word predictability influences eye fixation time for Chinese readers in a manner similar for readers of English (Rayner, Li, Juhasz, & Yan, 2005). Although Rayner et al. found that the pattern of skipping probabilities differed slightly between Chinese and English readers, the overall skipping rate did not differ much.
In this article, we address the question of how word and character frequency influence the eye movements of Chinese readers. In English, it is well-known that word frequency has a strong influence on fixation time on a word (Rayner, 1998). In Chinese, Yang and McConkie (1999) reported that both character complexity and word frequency influence fixation time on a word. Chen et al. (2003) used regression analysis techniques with Chinese adults' eye movement data and claimed that character complexity and frequency were more important than word frequency. They also reported regression analyses with children (2nd, 4th and 6th graders) that showed basically the same thing. While regression analyses are informative, such analyses can sometimes obscure certain aspects of data. For example, because frequency effects are attenuated with more exposures to target words (Rayner, Raney, & Pollatsek, 1995), such effects might not be as apparent in regression analyses across entire passages as they are in experiments. Issues of multicollinearity may also obscure the effects of predictor variables in regression analyses when those variables are themselves correlated (as is the case with character and word frequency in Chinese). Clearly, more work is needed to examine more precisely the extent to which word frequency influences the eye movements of Chinese readers. Furthermore, while prior studies have demonstrated that character complexity influences how long Chinese readers look at words, more information is …
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