中文摘要：

研究采用移动窗口范式考察不同字号文本对读者阅读知觉广度和眼动模式的影响。实验结果发现，被试阅读小字号（18磅）和大字号（36磅）文本时的阅读知觉广度都是四个字，这表明至少在一定范围内字号大小不影响读者的阅读知觉广度。但是与大号字（36磅）文本相比，被试阅读小号字（18磅）文本的平均注视时间和总注视时间更长，平均眼跳距离更短，相对眼跳距离（单位为字的个数）更长，注视次数更多，并且阅读速度更慢。该结果表明字号大小可以影响读者在阅读时的具体眼动模式和阅读效率。

英文摘要：

The perceptual span is the area of effective vision from which useful information can be obtained during a fixation in reading. Previous studies had proved that the perceptual span will be influenced by reading skill, the age of readers, the different working memo ry capacity and the difficulty of different Chinese materials. So these factors have a great influence on the ongoing cognitive processing in a reading task. The size of perceptual span is determined by ongoing cognitive processing. In alphabetic writing systems, the effect of visual acuity on eye movements has been widely discussed. For example, the saccade length （in characters） remained constant across changes in the number of characters per degree of visual angle（ Morrison ＆ Rayner, 1981 ）. In an recent reading study, the result indi cates that the saccade target selection in Chinese reading depends highly on visual acuity at the end of the tobe fixated word（ Shu, Zhou, Yan, ＆ Kliegl, 2011 ）. However, little was known about the perceptual span and eye movements of different visual acuity infor mation conditions in Chinese reading. So the present study was to investigate the effects of visual acuity （manipulated by font size） on the perceptual span and eye movements in Chinese reading. The results could address the following question： Is the perceptual span constrained mainly by visual acuity or by ongoing cognitive processing？ The experiment design was a 2 （ font size ： 18 pounds and 36 pounds） x 6 （ display conditions ： two characters, three characters, four characters, five characters, six characters and whole line condition）mixed design. The moving window paradigm was adopted in this experiment. Latin square design was adopted in the experiment. Various display conditions were blocked, and the order of condi tions was counterbalanced across participants. Twenty four native Chinese readers read 120 sentences under twelve experimental condi tions with their eye movements being monitored. The Eye movements were