The Characteristics of Bilingualism
Bilingual memory representation in the field of cognitive psycholinguistics focuses on how the bilingual brain operates，stores and organises two languages.Kroll and Stewart(1994)proposed“the bilingual memory representation of asymmetric mode”，as shown in Fig.5.1 below:
Fig.5.1 The asymmetrical model of bilingual representation
In bilingual memory，word and concept associations are activated simultaneously.When learning the target language，the link between the lexical realisation of the base language and the conceptual level(indicated by the solid diagonal arrow)is stronger than that between the target language and the conceptual level(dotted diagonal arrow).Similarly，the lexical link from target language to base(solid horizontal arrow)is stronger than that from base language to target(dotted horizontal arrow).With improved proficiency of learners’target language level，the strength of the links will change.
According to the asymmetric model of bilingual memory representation，two important conclusions can be drawn:first，the process of learning a target language is fundamentally different from that of acquiring one’s base language.When learning a target language，second language learners have already acquired a base language，stored a large number of concepts in their brain，and acquired thinking ability，and formed a relatively complete base language system closely related to their thinking ability.However，when learning a target language，second language learners always unconsciously use their base language for thinking activities and try to understand the concepts expressed in the target language by using the base language as an intermediary.Therefore，the learning of a target language does not start on a blank slate.The influence of the base language on the learning of a target language is an unavoidable problem，and the positive and negative transfer will be experienced by the second language learners.
Although the influence of base language on target language will be weakened when learners reach the advanced stage，it will never be completely eliminated.Therefore，in the process of second language teaching，especially in the initial stage，the appropriate use of the base language as an auxiliary tool of target language learning is completely in line with the cognitive psychology of bilingual learning.Furthermore，even for successful advanced second language learners，it is impossible for them to have exactly the same two-way translation ability between the two languages，and the receptive translation skill is better than the productive translation skill.