Abstract: It is well known that words were most important for alphabetic scripts reading (O’Regan & Jacobs, 1992). However, unlike alphabetic languages, Chinese texts consist of characters which take the same amount of horizontal extent, and there are no explicit boundaries between the words. Yang and McConkie (2004) proposed that Chinese readers developed oculomotor strategies that did not involve words. But recently, there were strong evidences supporting that word was the basic unit not only for comprehension of text but also for saccade target selecting (Bai, Yan, Liversedge, Zang, & Rayner, 2008; Yan, Kliegl, Richter, Nuthman, & Shu, 2010). We employed two disappearing text experiments aimed to resolve following confuses: First, was target selection of saccade based on characters or words? Second, if words, whether or not words in foveal and parafoveal vision, were identified serially or in parallel?
The sentences used in experiments were all composed of 7 to 10 two-character words. Our manipulations are as following: Experiment 1 contained four disappearing conditions and a control. In disappearing conditions, the fixated text disappeared after readers fixate on it 50~55ms. It reappeared immediately as the readers fixated on other text, and a refixation on the current text did not result in it reappearing. The disappearing conditions were (1) current character fixated disappeared, (2) current word fixated disappeared, (3) two adjacent characters (they were not belong to the same word) disappeared together when any of them was fixated, and (4) word n and word n+1 disappeared together when word n was fixated. We also conducted the Experiment 2, in which the word n-1, word n, word n+1, and the word n+2 disappeared respectively when word n was fixated after 50~55 ms.
The effects of the disappearing text manipulation on total reading times, number of fixations, and total runs of fixations were not reliable in the first experiment. There were significant effects of the presentation on mean saccade length, number of word refixated and skipped in the first experiment. The results of Experiment 2 have showed that readers spent more time on sentence reading when word n-1 disappearing than the normal. However, word n+1 and word n+2 disappearing conditions did not have any influence on the total reading time. The words refixated on word n disappearing condition was also less and words skipped on word n+1 disappearing condition was more than the control.
The gaze time, the number of words refixated and skipped supported the point of “saccade generating for target selection was word–based”, thus, the result of first experiment were compatible to cognitive control models rather than vision/oculomotor models. According serial computation models, word n-1 disappearing condition do not interrupt reading, word n+1 disappeared when word n was fixated after 50~55 ms does, however the results of both experiments showed were totally different from the predictions of serial computation models, such as E-Z Reader Model. The experiments were also largely been motivated by an important difference between serial and parallel computation models. So the results of both experiments provided evidences to support parallel processing models.

Key words: Chinese reading, disappearing text, eye movements, cognitive control models, parallel processing