Previous research on bilingual language processing has shed light on language control mechanism behind comprehension and speech production of bilinguals but the commonness or habitualness of code-switched terms in the design of the stimuli is seldom explored. This research attempted to explore the relationship between habitualness of code-switched terms and cognitive load level in Cantonese-English sight translation tasks among native Cantonese speakers in Macao through investigation from both objective and subjective data. The research collected and analysed eye-tracking data, audio data and NASA-TLX data. The results provided partial evidence that Macao native Cantonese speakers tended to experience lower cognitive load in the sight translation task when they were allowed to code switch the words they habitually applied in English; however, the correlation between code-switching and reduction of cognitive load was not significant. The findings suggest the selectivity of code-switching in language output and indicate that different levels of habitualness of the code-switched terms may modulate cognitive load.
