克拉申二语习得五假说

Krashen's five hypothesis
——Krashen's Monitor Theory Five basic hypotheses:
1) The Acquisition-Learning Hypothesis
Acquisition: naturally, subconscious,
informal,
Learning: consciously, formal, 'know about the second language, analysis and correction of errors formally and explicitly addressed.
Krashen supports this claim as follows:
(i) there can be acquisition without learning.
Competent language learners may
speak the language without consciously
knowing the rules.
(ii) there are cases where people can 'know' a rule but do not use it in normal
interaction.
(iii) in any case, nobody knows all the rules of a language. Grammatical explanations even in languages as widely studied as English do not cover the largely unconsciously knowledge of a native-speaker. It often takes linguists years to
describe rules which are relatively easily acquired (Ellis 1985).
Acquisition and Learning are not defined by 'where' a second language occurs. Formal learning in the street. The distinction is a central idea in education theory:
between deductive (推理:from general to particular) and inductive (归纟内［approaches; classroom and naturalistic learning; formal and informal language learning.
2) The Natural Order Hypothesis
Grammatical structures are acquired in a predictable order for both children and adults, irrespective of the language being learnt. Some rules tend to come early and others late. The order does not appear to be determined solely by formal simplicity and there is evidence that it is independent of the order in which rules are taught in language classes.
Whena learner engages in natural communication, then the standard order will occur.
3) The Monitor Hypothesis
The Monitor is an editing device that may operate before language performance.
Utterances may be modified by being acted upon by the Monitor of learnt knowledge. Such editing may occur before the natural output of speech; it may occur after the output via a correctingdevice.
Krashen suggests that monitoring occurs when there is sufficient time, when there is pressure to communicate correctly and not just convey meaning, and when the appropriate rules of speech are known.
Put it the other way:
1) there must be time for a speaker to use
conscious rules effectively. Normal
conversation does not allow for this
monitoring.
2) time alone is not enough. The speaker's attention must also be focused on Form.
3) the speaker must know the rule before the monitor can be used.
Examples include knowing the correct tense to use, when to use the third or first person and rules about plurals. This hypothesis has been criticized for being untestable and for a lack of supportive research evidence.
4) The Input Hypothesis
To explain how language acquisition occurs, Krashen proposes that when learners are exposed to grammatical features a little beyond their current level, those features are 'acquired'. Krashen emphasizes that 'acquisition' is the result of comprehensible language input and not of language production. Input is made
comprehensible because of the help provided by the context. If the language student receives understandable input, language structures will be, according to Krashen, naturally acquired. For Krashen, the ability to communicate in a second language
'emerges' rather than is directly put in place by teaching. Second language
is said to be caused by the process of understanding second language input.
Krashen lists a number of lines of evidence to support the input hypothesis:
O the sile nt period: this is based on the fact that childre n in an L2 situati on sometimes remain silent for several weeks. Similarly, young children are exposed to their mother tongue (and obviously understand it) before they begin to speak.
O age difference: younger learners mayget more comprehensible input because they tend to engage in 'here-and-now' interactions. Older learners may make faster progress initially, however, because they are exposed to more comprehensible input thanks to their broader world knowledge and because of the communicative strategies they have already developed in their L1.
O the effect of exposure: the more learners are exposed to comprehensible input, the more their language proficiency develops. Learners who do not have access to comprehensible input are held up in their development.
O immersion, bilingual and sheltered language teaching: students in these programs learn effectively because they receive comprehensible input where the focus is on the subject matter being taught rather than the form of the language.
O simple codes (care taker speech, motherese, foreigner talk, etc.) provide ideal input because (a) they are used to communicate meaning, not form, (b) they are roughly tuned to the learners' current level of linguistic competence, and they follow the 'here-and-now' principle which helps the learners understand.
O the effects of instruction: instruction is helpful when it is the primary source of comprehensible input. Formal instruction is only helpful because it is source
of comprehensible input. Methods that focus on comprehensible input are assumed to be superior to grammar-based or drill-based methods which focus on learning
Input is language which a learner hears or receives and from which he/she can learn. Intake is
input which is actually integrated into the learner's interlanguage.
'speakers acquire Ian guage in only one way - by un dersta nding messages, or by recei ving 'comprehe nsible (or better still comprehe nded) in put' •…Wemovefrom i, our current level, to i + 1, the next level along the natural order, by understanding input containing i +1'.
5) The Affective Filter Hypothesis
An affective filter was proposed by Dulay & Burt (1977) with the idea that there
is a filter that determines how mucha person learns in a formal orinformal language setting. The filter comprises affective factors such as attitudes to language, motivation, self-confidence and anxiety.
Thus learners with favorable attitudes and self-confidence may have 'a low filter' with consequent efficient second language learning. Those with unfavourable attitudes and / or high anxiety have 'high filters' and so the input of second language learning may be blocked or impeded. The affective filter proposed
by Krashen influences the rate of development in second language learning and the level of success in becoming bilingual.
Krashen: comprehensible input may not be utilised by second language acquirers if there is a 'mental block' that prevents them from fully profiting from it. If the affective barrier is down . when the learner is motivated, confident, and not anxious), comprehensible input reaches the Language Acquisition Device.
The affective filter has 4 functions:
i) it determines the selection of language models;
ii) it determines which part of the language will be attended to first;
iii) it determines when language acquisition efforts should cease;
iv) it determines the speed of acquisition
Summary of the 5 hypothesis
'People acquire second languages only if they obtain comprehensible input and if their affective filters are low enough to allow the input 'in'. When the filter is 'down' and appropriate comprehensible input is presented (and comprehended), acquisition is inevitable
It is, in fact, unavoidable and cannot be prevented - the language 'mental organ' will function just as automatically as any other organ'
(Krashen 1985:4)
Krashen's theory applied to the classroom (discuss)
(1) the goal of teaching must be to supply understandable input in order for the child or adult to acquire language easily. A good teacher therefore is someonewho continuously delivers at a level understandable by the second language speaker.
Just as father/mother talk (motherese) helps the young child to acquire the first language by a simplified and comprehensible language (and nonverbal language), so an effective teacher is said to facilitate second language learning by ensuring a close match between the level of delivery and the level that is understandable.
(2) teaching must prepare the learner for real life communication situations. The classroom needs to provide conversational confidence so that, when in the outside world, the student can both linguistically cope and continue language learning.
Language and communication are the two sides of the same coin.
Teachers should provide opportunities for communication. McNamara (1973) has argued that
'the really important part of motivation lies in the act of communication.
Rossier (1975) also emphasizes the importance of a desire to communicate, arguing that without this, students' motivation may not be effective. It is the need to get meanings across and the pleasure experienced whenthis is achieved that provides the motivation to learn an L2. Teachers also should provide opportunities for group work.
Teachers should try to ensure that students' interest is engendered as a result of a good rapport with the learners. As Finocchiaro (1981) puts it:
The moment of truth--- the enhancement of motivation--- occurs when the teacher closes the classroom door, greets his students with a warm, welcoming smile, and proceeds to interact with various individuals by making comments or asking questions which indicate personal concern.
(3) teachers must ensure that learners do not become anxious or defensive in
language learning. This relates to the Affective Filter hypothesis. The confidence of the learner must be encouraged in a language acquisition process.
Whena learner is relaxed, confident and not anxious, then the input of the classroom situation will be more efficient and effective. If teachers insist on children conversing before they feel comfortable in doing so, or a teacher constantly corrects errors and makes negative remarks, the learner may feel inhibited in learning.
(4) formal grammar teaching is of limited value because it contributes to learning rather than acquisition. Only simple rules should be learnt. Complex rules will not be used consciously or unconsciously by the language learner. Therefore, there appears little to be gained from formally teaching the rules of a second language.
(5) errors should not be corrected when acquisition is occurring. They may be corrected when the goal is formal learning. Error correction is valuable when learning simple rules but may have negative effects in terms of anxiety and inhibition.
For Krashen, a 'Natural Approach' is required in language teaching. The Natural
Approach is very different form traditional grammar teaching and language
laboratory types of approach. Its main tenets are as follows: communicative skills should be the aim of the good language classroom; comprehension of language should precede production (listening should precede speaking);
speaking and then writing will emerge when the language learner is ready and should not be forced; acquisition rather than formal learning is central in good language learning; and the affective filter needs to be kept low.
Problems with the Monitor Model
McLaughlin (1987) criticises Krashen for not defining his terms with enough precision and for basing his theory on weak empirical evidence. The theory, furthermore, fails to make clear predictions. McLaughlin lists the following problems:
★the learning -acquisition distinction is not clearly enough defined to allow for empirical testing. Leakage from learnt to acquired seems not only possible but well-substantiated.
When 'learnt' knowledge is automatised through practice it becomes 'acquired' ., available for spontaneous use).
★variation is explained in terms of monitored and unmonitored performance andthere is no provision for partial monitoring . the Monitor is either on or off).
Sociolinguistic research, however, shows that all speakers engage in 'small-m' monitoring in that their speech varies on a careful-non-careful continuum according to the level of attention to form. This attention to form does not necessarily imply the use of articulated rules of usage.
★Krashen's case for the natural order hypothesis is based largely on morpheme studies which are questionable and provide little information about the process of acquisition because they focus on final form . the product).
★the input hypothesis is untesta ble because no definition is given of 'comprehensible input' or of the constructs i and i +1. The hypothesis also fails to explain the elimination of incorrect intermediate forms in the learner's interlanguage and provides no way of distinguishing between different instructional methods because each,
if effective, can be argued to provide comprehensible input. There seems a contradiction between the emphasis placed on the crucial component of 'rough tuned' input (the external environment) and the natural order hypothesis (an internal process).
★the affective filter hypothesis is vague and does not explain how the filter develops or why, for example, it affects language acquisition in adults but not in children. Affectivity may just as well influence a learner's conscious learning by interfering with or aiding concentration, memory, hypothesis formation, or assiduity.
△many researchers agree with Krashen on basic assumptions such as the need to move from grammar-based to communication-based instruction, the role of affective factors in language learning and the importance of acquisitional sequences in second language acquisition.
The theory has, nevertheless, been criticized because it tries to achieve too much and makes assertions which cannot be proved or, indeed, contradicted by empirical evidence.。