Abstract
Previous ERP and fMRI studies have shown that concurrent processing of units from alphabetic and non-alphabetic writing systems, such as Roman letters and Chinese characters, activate overlapping brain regions. It is unknown, however, whether different types of characters simply recruit separate yet nearby neural networks, or rather there are shared mechanisms for expert processing of characters independent of writing system. Here we study the functional overlap of expert character processing for different writing systems by examining the interference in a visual search task involving processing of multiple types of characters. Chinese-English bilinguals and English readers were asked to search for target Roman letters among images presented sequentially in a rapid serial visual presentation (RSVP) stream. The search for Roman letters occurred either in a sequence of Roman and Chinese distractors, or in a sequence of Roman and Pseudoletter distractors. Bilinguals performed worse than English readers during Roman letter search among Roman and Chinese characters, whereas there was no group difference in performance during Roman letter search among Roman and Pseudoletter distractors. In other words, the addition of Chinese distractors affected Roman letter search only for bilinguals. The existence of familiar distractors (Chinese characters for bilinguals) alone was insufficient to explain the finding. This can be shown in English readers, who performed similarly when searching for Pseudoletter targets among Pseudoletter and Roman (familiar) distractors compared with searching among Pseudoletter and Chinese (unfamiliar) distractors. Overall, we showed common expert processing mechanisms shared by characters in both alphabetic and non-alphabetic writing systems.
This research was supported by the Direct Grant (2020939) from the Chinese University of Hong Kong and the General Research Fund (452209) from the Research Grants Council of Hong Kong to A.W. and through the Temporal Dynamics of Learning Center (NSF Science of Learning Center SBE.