The predictability of an upcoming word has been found to be a useful predictor in eye movement research, but is expensive to collect and subjective in nature. It would be desirable to have other predictors that are easier to collect and objective in nature if these predictors were capable of capturing the information stored in predictability. This paper contributes to this discussion by testing a possible predictor: conditional co-occurrence probability. This measure is a simple statistical representation of the relatedness of the current word to its context, based only on word co-occurrence patterns in data taken from the Internet. In the regression analyses, conditional co-occurrence probability acts like lexical frequency in predicting fixation durations, and its addition does not greatly improve the model fits. We conclude that readers do not seem to use the information contained within conditional co-occurrence probability during reading for meaning, and that similar simple measures of semantic relatedness are unlikely to be able to replace predictability as a predictor for fixation durations. Keywords: Co-occurrence probability, Cloze predictability, frequency, eye movement, fixation duration.
The present study explored the age-related changes of eye movement control in reading-that is, where to send the eyes and when to move them. Different orthographies present readers with somewhat different problems to solve, and this might, in turn, be reflected in different patterns of development of reading skill. Participants of different developmental levels (Grade 3, N = 30; Grade 5, N = 27 and adults, N = 27) were instructed to read sentences for comprehension while their eye movements were recorded. Contrary to previous findings that have been well documented indicating early maturation of saccade generation in English, current results showed that saccade generation among Chinese readers was still under development at Grade 5, although immediate lexical processing was relatively well-established. The distinct age-related changes in eye movements are attributable to certain linguistic properties of Chinese including the lack of interword spaces and word boundary uncertainty. The present study offers an example of how human eye movement adapts to the orthographic environment.