Usability evaluation of E-books

The eye movements of native English speakers, native Chinese speakers, and bilingual Chinese/English speakers who were either born in China (and moved to the US at an early age) or in the US were recorded during six tasks: (1) reading, (2) face processing, (3) scene perception, (4) visual search, (5) counting Chinese characters in a passage of text, and (6) visual search for Chinese characters. Across the different groups, there was a strong tendency for consistency in eye movement behavior; if fixation durations of a given viewer were long on one task, they tended to be long on other tasks (and the same tended to be true for saccade size). Some tasks, notably reading, did not conform to this pattern. Furthermore, experience with a given writing system had a large impact on fixation durations and saccade lengths. With respect to cultural differences, there was little evidence that Chinese participants spent more time looking at the background information (and, conversely less time looking at the foreground information) than the American participants. Also, Chinese participants' fixations were more numerous and of shorter duration than those of their American counterparts while viewing faces and scenes, and counting Chinese characters in text.

Eye-movement-contingent display changes were used to control the visibility of characters during the reading of Chinese text. Characters outside a window of legible text were masked by dissimilar characters, and effects of viewing constraints were ascertained in several oculomotor measures. The results revealed an asymmetric perceptual span that extended 1 character to the left of the fixated character and 3 characters to its right. The size of right-directed saccades extended across 2 to 2 1/2 character spaces, indicating that the perceptual spans of successive fixations overlapped slightly and that some linguistic information was integrated across fixations. The relatively small spatial overlap of successive spans appears to reflect a text-specific process. However, the results also revealed substantial similarities in the coding of morphographic Chinese and alphabetic English texts, indicating that text-specific coding routines are subordinated to general coding principles.