The ‘medium-of-learning effect’: Why the EDB guideline banning classroom code-switching is so difficult to follow

Code-switching (CS) is generally perceived as bad/pathological language behavior in society and the classroom. The putative causal relationship between CS and declining language standards is widely shared but supported by little empirical evidence. While switching to Chinese students’ first language, Cantonese, arguably reduces their exposure to English in EMI lessons, it overlooks the constructive role of CS in facilitating understanding as they struggle with the daunting task of learning content subjects in an unfamiliar language. Bilingual classroom research has shown that CS, used judiciously by teachers proficient in both the students’ first language and the language of ‘immersion’, may be pedagogically conducive, e.g., by making abstract and alien concepts cognitively more accessible, and maintaining class discipline. This paper presents empirical evidence of why CS is so difficult to avoid. Data were drawn from a project involving 108 educated Chinese-English bilinguals in Hong Kong and Taiwan. The ‘One day with only Cantonese/Mandarin’ experiment required them to use only their dominant community language for one day. The primary objective was to find out under what circumstances Chinese-English bilingual students would feel the need to codeswitch. The analysis of 108 reflective diaries and 13 two-hour focus-group interviews suggests that learning through the medium of English makes English-L2 students cognitively dependent on specialized terminologies in English. The tendency of cognitive dependence on English was clearly much stronger among participants in Hong Kong than in Taiwan. The findings point toward a psycholinguistic ‘medium-of-learning effect’ in the development of bilinguality. Implications for classroom code-switching will be discussed.