YEAR TWO Second Language Acquisition
#8: Stephen Krashen's Second Language Acquisition Theory
In the late 1970s and early 1980s, the eminent American psycholinguist Stephen D. Krashen (e.g., 1977; 1981;
1982; 1985) developed five main hypotheses about second-language acquisition, viz.:
·ð the Acquisition-Learning Hypothesis ·ð the Monitor Hypothesis
·ð the Input Hypothesis ·ð the Affective Filter Hypothesis
·ð the Natural Order Hypothesis
1. The Acquisition-Learning Hypothesis (the Dual Competence model)
This hypothesis states that "adults have two distinct and independent ways of developing competence in a second
language" (Krashen 1982: 10): acquisition, which is subconscious and which is to be identified with LAD, and
learning, which is conscious and which is how most people access a foreign language in schools. The remaining
fundamental differences can be summarised thus: acquisition vs. learning
Ä…ð similar to child first-language acquisition Ä…ð formal knowledge of language
Ä…ð 'picking up' a language Ä…ð 'knowing about' a language
Ä…ð implicit knowledge of grammar Ä…ð explicit knowledge of grammar
Ä…ð formal teaching does not help Ä…ð formal teaching helps
In the light of the above, learning is a conscious process for developing ability in language. It does not involve the
use of the language 'mental organ' or LAD, but uses other faculties of mind to produce language-like behaviour
(Krashen 1985: 102). Consequently, 'conscious learning' is the result of a separate 'faculty of mind', outside the
language mental organ, and perhaps part of the 'science-forming' capacity used for gaining other knowledge as well
(Chomsky 1975: 24). On the other hand, the hypothesis under consideration claims that "no change is posited in
the LAD at puberty or at any other age, nor does the LAD degenerate. It also allows the possibility that 'perfect' post
puberty second-language acquirers may exist it predicts that such individuals will have had plenty of exposure to
comprehensible input, and will have very low affective filters" (Krashen 1985: 13).
2. The Input Hypothesis
According to the hypothesis in question, we are able to understand language containing unacquired grammar with
the help of context, which includes extralinguistic information, our knowledge of the world, and previously acquired
linguistic competence. In more technical terms, Krashen claims that we acquire language by understanding input
that is a little bit beyond our current level. His i + 1 formula is to be interpreted like this: the "i" is the acquirer's
current competence, or the last rule acquired along the natural order, and the "i + 1" means the next rule the
acquirer is 'due to' acquire or is eligible to acquire along the natural order (Krashen 1985: 101). Thus, listening
comprehension is of primary importance in the language programme and the ability to speak or write fluently in the
second language will come in its own time. Spoken fluency is thus not 'taught' directly; rather, speaking 'emerges'
after the acquirer has built up competence through comprehending input. Second-language competence develops
via output practice in communicative situations.
The strongest claim that the Input Hypothesis makes is that certain skills are attainable only indirectly, that true
competence in speaking, writing and grammatical accuracy are developed only via listening and reading for
meaning (Krashen 1985: 92). For example, speech is thus believed to be a result of acquisition and not its cause.
Krashen claims that speech cannot be taught directly but 'emerges' on its own as a result of building competence
via comprehensible input (Krashen 1985: 2).
Krashen emphasises the role of caretaker speech in providing comprehensible input. A teacher may try to fine tune
the input so that the student gets exactly i + 1 comprehensible input, but Krashen claims this is not so useful as
rough tuned comprehensible input where the speaker concentrates on communicating by getting the message
understood. This is what happens in caretaker speech (for children acquiring their first language) and in foreigner
talk. Thus, in teacher talk the instructor should concentrate on the message and so comprehensible rough tuned
input will be achieved. One of the best ways a teacher can do this is by doing class management and instructions in
the target language.
3. The Natural Order Hypothesis
This hypothesis states that we acquire the rules of language in a predictable order, some rules tending 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. Krashen (1985: 1) claims that, like
in first language acquisition, there is a natural order in the acquisition of grammatical structures in L2. Krashen
claims that the average order of grammatical morphemes is as follows:
PROGRESSIVE (-ing)
PLURAL (-s)
COPULA (to be)
AUXILIARY (PROGRESSIVE be)
ARTICLE (a, the)
IRREGULAR PAST (e.g. went)
REGULAR PAST (-ed)
3rd PERSON SINGULAR (-s) VERB
POSSESSIVE (-s)
Krashen believes that this order is derived from an analysis of empirical studies of second language acquisition and
is the same for people from different language backgrounds.
4. The Monitor Hypothesis
Krashen claims that conscious learning has a limited function in adult second language performance: it can only be
used as a monitor or editor. Our fluency in the second language comes from what we have acquired or 'picked up' in
natural communicative situations. Our 'formal knowledge' of a second language comes from rules we have learned
in class and from textbooks. Its function, according to Krashen, is to make repairs on the output of the acquired
system. For the monitor to be used successfully, three conditions must apply; the performer has to:
·ð have enough time (however, is this possible in normal conversation?)
·ð be focused on the form (and he must want to produce correct sentences)
·ð know the rule (but is it possible to know all the rules?)
While focusing on form may result in somewhat more grammatical accuracy, it does take more time. In a study
using adult subjects, it was reported that focusing on form took about 30 per cent longer and resulted in about 14
per cent less information transmitted (Hulstijn & Hulstijn 1984). This may seriously disrupt communication in
conversational situations (Krashen 1985: 2).
5. The Affective Filter Hypothesis
Krashen claims that there are many attitudinal factors which may prevent an acquirer 'taking up' the comprehensible
input. Such factors as stress, low self-esteem, lack of motivation may mean that the filter is up or high, so
acquisition does not take place. For example, the filter is typically 'up' when the acquirer is anxious, lacking in self-
confidence, or unmotivated, when he is 'on the defensive' (Stevick 1976), when he considers the language class to
be a place where his weaknesses will be revealed (Krashen 1985: 3). It is the task of the teacher to try and make the
atmosphere conducive to acquisition.
input filter intake LAD / UG acquired competence monitor output
("the black box")
According to Krashen (1985: 3), "the acquirer needs to be 'open' to the input. The 'affective filter' is a mental block
that prevents acquirers from fully utilising the comprehensible input they receive for language acquisition. When it
is 'up', the acquirer may understand what he hears and reads, but the input will not reach the LAD."