Eye movements within the scope of AOI in the unilingual (pure Chinese) and intra-sentential code-switching (Chinese and English) contexts and at three word-frequency levels were compared respectively, and the switch cost in the intra-sentential code-switching contexts was examined. Through the paired sample t-test, and the five observation points’ (FFD, FTT, FC, RC, and DT) analysis of the M and SD and the ANOVA for repeated measure within the scope of AOI at three word-frequency levels, it was found that the subjects’ scores in the intra-sentential code-switching contexts were higher than those in the unilingual ones; that if a switching cost occurred, it was not necessarily at the switching site; technical words in alternating languages did impair performance even when the switch occurred at a sentence boundary; word frequency had some effect on word recognition speed in the unilingual contexts instead of the code-switching ones.
Key Words: eye movement measure of AOI; unilingual; intra-sentential code-switching; switch cost; word frequency