Abstract: Readers obtain information from the word to the right of fixation and this effect was named preview benefit. Previous studies have indicated that the closer the launch site to the target word, the greater the preview benefit from the target word was observed (Briihl & Inhoff, 1995; McDonald, 2006; Rayner, McConkie, & Zola, 1980). Further, Kliegl, Hohenstein, Yan and Mcdonald (2012) reanalyzed McDonald's (2006) data and found that preview effects, which are typically summarized as “preview benefit”, were a complex mixture of preview cost and preview benefit. They suggested that the decrease in fixation time under the identical preview conditions was caused by the facilitation of processing, which belonged to "preview benefit"; and the increase in fixation time under the different preview conditions was due to interruption of invalid information and thus belonged to "preview cost". The current study was set up to examine the effect of saccade launch site on preview processing and discriminate the preview benefit and preview cost during reading of Chinese. Different from the previous studies that launch site was not experimentally controlled and its effect was evaluated by covariate analyses, the current experiment manipulated the position of the target word in the sentence and thus the launch site of the saccade to the target word. This is because the average saccade length of Chinese readers is 2-3 Chinese characters (Inhoff, 1998), when the target word is the fourth word and the fifth character (two-character word) in the sentence, it is very likely that the fixation to the target word was launched from the 3rd character. We referred this situation as launch site from a “short distance” condition. In contrast, we added 3-5 characters to the beginning of these sentences and pushed the target words further away from the sentence beginning. As the distance between the sentence beginning and the target word position became larger, the launch site to the target word could not be systematically close to the target word. For comparison, we referred this situation as launch site from a “long distance” condition. Another factor in the experiment was preview condition, including identical (to the target word) and different (from the target word) previews. The main result suggested that the preview effect, which was reflected by the difference between the identical and the different preview condition on the target word, was larger in gaze duration and go-past time when the saccade to the target word was launched from a long distance, as compared from a short distance. A further analysis indicated that the nature of these preview effect was actually a preview cost as the different preview brought larger difficulties in the long distance condition. It is worth noting that the preview effects, which are typically referred as "preview benefit", are actually a complex mixture of preview cost and preview benefit in reading Chinese. The current experiment helps people to understand the two kinds of preview effects and also factors may influence them.

Key words: eye movements, reading, preview benefit, preview cost, launch site

摘要： 本文试图用实验的方法，通过调整目标词在句子中的位置，操纵目标词上注视点的眼跳发起位置，考察该变量对预视效应的影响。主要结果发现，和目标词上注视点的眼跳发起距离近的条件相比，眼跳发起距离远时凝视时间和回视路径时间的预视效应更大；但对数据的进一步分析表明这是一种阻碍效应。虽然“预视效益”这个词常用来代表预视加工，它实质包含了预视促进和阻碍两种不同的加工。本研究的结果有助于大家理解这两种不同性质的加工及其可能的影响因素。

关键词: 眼动 阅读 预视效益 预视阻碍 眼跳发起位置