Chapter Two Literature Review
This chapter is mainly to review some research literature relevant to the presentstudy. For Uyghur college students，learning English as a third language necessarilyinvolves the cross-linguistic influence (CLI) from their known languages. Therefore，this chapter will start with the studies on cross-linguistic influence.
2.1 Studies on Cross-linguistic Influence
In recent years，cross-linguistic influence (CLI) has become a focus in thirdlanguage acquisition. As we all know, the knowledge of a known language must havesome impact on the acquisition of the target language. Language transfer always playsan important role in the acquisition of L2 and L3.During the 1940s - 1960s, many linguists and researchers studied languagetransfer from the academic perspective, and regarded transfer as an inevitablecharacteristic in language learning and use (Fries，1945; Weinreich, 1953; Haugen,1953; Lado，1957). Weinreich (1953) first defined transfer as "a phenomenon ofdeviating from any kind of language norm occurred in the bilingual speaking". Thisdefinition is focused on the negative transfer, because it considers the influeiice ofmother tongue as the obstacle of the acquisition and production of correct targetlanguage.In the 1980s，the definition of transfer made by Odlin (1989) was mostlyaccepted and often cited, because this definition encompasses many differentviewpoints: "transfer is the influence resulting from similarities and differencesbetween the target language and any other language that has been previously (andperhaps imperfectly) acquired，，（Odlin，1989). Odlin also pointed out that any studyof transfer cannot neglect the significance of trilingual and other multilingualsituations. The knowledge of two known languages may both affect the acquisitionof a third language (Odlin, 2001).Language transfer includes both positive transfer and negative transfer inaccordance with the varied effects produced by cross-lingxxistic similarities anddifferences. Accordingly, Kellerman & Smith (1986) proposed the neutral concept:cross-linguistic influence, referring to "allowing one to subsume under one headingsuch phenomena as transfer, interference, avoidance, borrowing, and L2-relatedaspects of language loss and thus permitting discussion of the similarities anddifferences between these phenomena."Cross-linguistic influence is a complicated cognitive phenomenon, ofteninfluenced by the perception, conceptualization, psychological association andpersonal choice of language users. There are many factors causing cross-linguisticinfluence，such as language types, learners' perceived language distance(psychotypology), language contact, language status，the learner's
