In Years 1 and 2, the OVP curve was observed with lexical decision task (during which a word was presented in isolation) and normal text reading task. In Year 1, the stimuli were middle to low frequency words whose NS1 and NS2 were less than 30 with means 12.3 and 12.0, respectively. We observed an OVP slightly to the right of the center of two-character words. The observation of rightward asymmetric OVP curve was inconsistent with findings in other languages. However, the OVP near the second-character of word-ending may result from the special property of Chinese text which has no space between words to indicate word boundary. Chinese readers may have learned that word-ending provides the disambiguating information and they read faster at the second-character position even in the isolated presentation task.
In Year 2, we analyzed OVP in continuous text reading. For two-character words, the probability of fixating word center was higher than that of word boundaries (preferred viewing location, PVL) and the probability of refixating the target word was lower when readers initially landed at word center (which implies the OVP). For three-character words, the PVL was slightly to the left of word center, while the OVP was near the word ending. Presumably because there was no visual cue for word boundaries, readers tended to fixate at word beginning; but for a long word, it was easier to determine word boundary when word ending was fixated. In a linear mixed-effects analysis (Baayen, et al., 2008), we found that gaze durations on words were shorter when the second character
was more likely to be used as word ending. Similarly, GDs were shorter when the first character was more likely to be used as word beginning (but this effect was less robust).
Also, the effect was more evident when the other character was less likely to be used at its current position. This finding suggests that Chinese readers are sensitive to statistical information such as the probability of within-word character position for word recognition during text reading. Although the second character seemed to produce a reliable effect, it was modulated by the congruency of the first character. This suggests that both characters have their effects during text reading.
In Year 3, we directly investigated how the information profile of sub-lexical units influences lexical processing. In Experiment 3-1, effects of neighborhood sizes of both constituent characters on recognizing two-character words were examined. We found that the first character played a dominant role. When NS1 was small, it was easy to recognize the target word, so there was no effect of fixation position. When NS1 was large, an OVP to the left of word center was found. The findings suggest that the OVP is affected by lexical constraint or information profile of words which play a role in the process of word recognition.
A different picture was observed for character recognition in Experiment 3-2.
Semantic combinability exerted an inhibitory effect while phonetic combinability exerted a facilitative effect. In addition, effect of one radical combinability was more evident when the other radical was less informative and when the other radical was fixated. These results suggest both radicals play important roles during character recognition. Unlike constituent characters in multi-character words, the function and the position of a radical in characters are highly related. Specifically, a majority of semantic-phonetic compound characters have their semantic radical at the left hand side and their phonetic radical at the right hand side. The close relationship between radical position and function may lead to the observation that both semantic and phonetic radicals are important for character recognition although they play different roles.
Taken together, whether one sub-lexical unit plays a dominant role or both units are equally important depends on the relationship between the function and position of the sub-lexical unit as well as on the task they involve in. In this project, the effects of the information profile of the sub-lexical units have been repeatedly observed under different
conditions. Using statistical information to decode the presented stimuli seems to be an implicit but common strategy during reading. Manipulating fixation position together with the informativeness of the sub-lexical units is a good technique to study this cognitive operation. In addition, the characteristics of Chinese writing system also provide a unique platform for this issue.
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