Chapter I Introduction Describing and Explaining L2 Acquisition 1.1What is second language acquisition?Second language refers to any language that is learned subsequent to the mother tongue.1.2What are the goals of second language?The goals of SLA are to describe how L2 acquisition proceeds and to explain this process and why some learners seem to be better at it than others.1.3Two case studies of L2 learners1.3.1 A case study of an adult learner1.3.2 A case study of two child learnersWhat do these case studies show us?a. They raise a number of important methodological issues relating to how L2 acquisition should be studiedb. They raise issues relating to the description of learner languagec. They point out some of the problems researchers experience in trying to explain L2 acquisition.1.4Methodological issuesWhat is that needs to be described?a. What it means to say that a learner has acquired a feature of the target language?b. Whether learners have acquired a particular feature?c. How to measure whether acquisition has taken place? (Learner’s overuse of linguistic forms.)1.5Issues in the description of learner languagea. Learners make errors of different kinds.b. Learners acquired a large number of formulaic chunks, which will influence their performancein communication and the fluency of their unplanned speech.c. Whether learners acquire the language systematically?1.6Issues in the explanation of L2 acquisitionItem learning: formulaic chunksSystem learning: rulesInternal (mentalist) account:External account:Chapter2 the Nature of Learner Language2.1Errors and error analysis2.1.1 Identifying errors2.1.1.1 Compare the learner’s language with the normal ones.2.1.1.2 Distinguish errors and mistakes.Definition: Errors reflect gaps in a learner’s knowledgeMistakes reflect occasional lapses in performance.Methods: a. Check the consistency of learners’ performance.b. Ask them to correct their own utterance.Errors and mistakes:2.1.2 Describing errorsMethods: a. error type oriented:b. error maker oriented:Meaning: Classifying errors in these ways can help us to diagnose learners’learning problems at any one stage of their development and, also to plot how changes in error patterns occur over time.2.1.3 Explaining errorsErrors are systematic, predictable, and some of them are universal: (Learners has constructed some kind of “rule”, albeit a rule different from that of the target language) Eg: omission: leave out the article “the”, leave out the –s in plural nounsOvergeneralization error: eated---ateTransfer errors reflect learners attempt to make use of their L1 knowledge.2.1.4 Error evaluationTypes of errors: Global errors: violate the whole structure of the sentenceLocal errors: affect only a single constituent in the sentence2.2Developmental patterns2.2.1 The early stage of L2 acquisitionSilent period: children make no attempt to say anything to begin with.This period makes a preparation for subsequent production.Trials and errors: Mulaic chunks: they provide learners with the means of performing usefullanguage functions such as greetings and requests.Eg:“How do you do?”“My name is___”Propositional simplification: leave words outEg: “Me no blue”2.2.2 The order of acquisitionAccuracy order: there is a definite accuracy order and that this remains more or less the same irrespective of the learner’s mother tongues, age, and whether or not they have receive formal language instruction.2.2.3 Sequence of acquisitiona. The acquisition of a particular grammatical structure, therefore, must be seen as a process involving transitional constructions.b. Acquisition follows a U shaped course of development.c. The process in which learners reorganize their existing knowledge in order to accommodate new knowledge is called restructuring.2.2.4 Some Implicationsa. L2 is systematic and universal, reflecting ways in which internal cognitive mechanisms control acquisition, irrespective of the personal background of learners or the settings in which they learn.b. Some linguistic features are inherently easier to learn than others.2.3Variability in learner languagea. Variability is also systematic, that is, learners use their linguistic sources in predictable ways.b. Learners vary in their use of the second language according tolinguistic context (George playing football/ ..all the time)situational context.(kids/daughter)& psycholinguistic context (prepared/unprepared)c. form-function mappingd. free variation:e. fossilization:石化成因任何现象的出现都不是偶然的,是可以追溯出它的原因的,二语习得过程中出现的中介语石化现象也是有着根本性的原因的。