Abstract:

In written Chinese, over 80% of characters are compounds, in which independent constituents called radicals can be considered as the sub-lexical units. Some radicals can appear at different positions within a character. For instance, the radical 口 can appear on the left of 听 (listen), on the right of 知 (know), at the top of 呆 (stupid), or at the bottom of 杏 (apricot). The primary concern in prior behavioral studies on radical processing is whether radicals are represented with or without position in the Chinese lexicon (i.e., position-specific or position-general, respectively). However, ERP results confirmed that both position-specific and position-general radical representations existed in human mental lexicon. The new argument is that whether the position-specific radicals are activated at the first stage in character recognition, as reflected by the N/P150 effects. Although prior studies revealed that position-specific radical processing was related to the N/P150, the tasks used in those studies were not natural enough to reflect the situation in conventional reading. Therefore, unlike prior studies, a Go/NoGo semantic categorization task was used in the present study, which could guarantee the requirements in daily life reading. Using event-related brain potentials (ERPs), two types of radical information were manipulated: the number of characters containing a specific radical irrespective of position (i.e., frequency as a position-general radical) and the number of characters containing a specific radical at a particular position (i.e., frequency as a position-specific radical). The results showed that the effects of position-specific and position-general radical frequency were both related to P200 and N400. Characters of low radical frequency evoked a larger P200 and a smaller N400 than their high frequency counterparts. Moreover, no difference was found between the peak latency of the two P200 effects. More importantly, no N/P150 effects were found to be associated with the processing of position-general and position-specific radicals. Given that both position-general and position-specific radical frequency would influence the radical position dominance (the degree of dominance was calculated by dividing the sum frequency of characters that shared the same radical in each possible position by the total frequency of all characters sharing the radical irrespective of position; dominance = position-specific radical frequency / position-general radical frequency), both results associated with effects of position-specific and position-general radicals reflected the processing of radical position. Therefore, the current results indicate that radical position plays an important role in Chinese character reading, which influences not only the sub-lexical orthographic processing, but also the character semantic activation.

Key words: position-specific radical, position-general radical, ERPs, semantic categorization task