Stephen Krashen's Theory of Second Language Acquisition
Stephen Krashen
Language acquisition does not require extensive use of
conscious grammatical rules, and does not require tedious drill.
Acquisition requires meaningful interaction in the target language
- natural communication - in which speakers are concerned not with the form of
their utterances but with the messages they are conveying and understanding.
The best methods are therefore those that supply
'comprehensible input' in low anxiety situations, containing messages that
students really want to hear. These methods do not force early production in
the second language, but allow students to produce when they are 'ready',
recognizing that improvement comes from supplying communicative and comprehensible
input, and not from forcing and correcting production.
In the real world, conversations with sympathetic native
speakers who are willing to help the acquirer understand are very helpful.
Introduction
Stephen Krashen (University of Southern California) is an
expert in the field of linguistics, specializing in theories of language
acquisition and development. Much of his recent research has involved the study
of non-English and bilingual language acquisition. During the past 20 years, he
has published well over 100 books and articles and has been invited to deliver
over 300 lectures at universities throughout the United States and Canada.
This is a brief description of Krashen's widely known and
well accepted theory of second language acquisition, which has had a large
impact in all areas of second language research and teaching since the 1980s.
Description of Krashen's Theory of Second Language
Acquisition
Krashen's theory of second language acquisition consists of
five main hypotheses:
the Acquisition-Learning hypothesis;
the Monitor hypothesis;
the Natural Order hypothesis;
the Input hypothesis;
and the Affective Filter hypothesis.
The Acquisition-Learning distinction is the most fundamental
of all the hypotheses in Krashen's theory and the most widely known among
linguists and language practitioners.
According to Krashen there are two independent systems of
second language performance: 'the acquired system' and 'the learned system'.
The 'acquired system' or 'acquisition' is the product of a subconscious process
very similar to the process children undergo when they acquire their first
language. It requires meaningful interaction in the target language - natural
communication - in which speakers are concentrated not in the form of their
utterances, but in the communicative act.
The "learned system" or "learning" is
the product of formal instruction and it comprises a conscious process which
results in conscious knowledge 'about' the language, for example knowledge of
grammar rules. According to Krashen 'learning' is less important than
'acquisition'. (Veja o texto ao lado e também outra página em português sobre
Acquisition/Learning).
The Monitor hypothesis explains the relationship between
acquisition and learning and defines the influence of the latter on the former.
The monitoring function is the practical result of the learned grammar.
According to Krashen, the acquisition system is the utterance initiator, while
the learning system performs the role of the 'monitor' or the 'editor'. The 'monitor'
acts in a planning, editing and correcting function when three specific
conditions are met: that is, the second language learner has sufficient time at
his/her disposal, he/she focuses on form or thinks about correctness, and
he/she knows the rule.
It appears that the role of conscious learning is somewhat
limited in second language performance. According to Krashen, the role of the
monitor is - or should be - minor, being used only to correct deviations from
"normal" speech and to give speech a more 'polished' appearance.
Krashen also suggests that there is individual variation
among language learners with regard to 'monitor' use. He distinguishes those
learners that use the 'monitor' all the time (over-users); those learners who
have not learned or who prefer not to use their conscious knowledge
(under-users); and those learners that use the 'monitor' appropriately (optimal
users). An evaluation of the person's psychological profile can help to
determine to what group they belong. Usually extroverts are under-users, while
introverts and perfectionists are over-users. Lack of self-confidence is
frequently related to the over-use of the "monitor".
The Natural Order hypothesis is based on research findings
(Dulay & Burt, 1974; Fathman, 1975; Makino, 1980 cited in Krashen, 1987)
which suggested that the acquisition of grammatical structures follows a
'natural order' which is predictable. For a given language, some grammatical
structures tend to be acquired early while others late. This order seemed to be
independent of the learners' age, L1 background, conditions of exposure, and
although the agreement between individual acquirers was not always 100% in the
studies, there were statistically significant similarities that reinforced the
existence of a Natural Order of language acquisition. Krashen however points
out that the implication of the natural order hypothesis is not that a language
program syllabus should be based on the order found in the studies. In fact, he
rejects grammatical sequencing when the goal is language acquisition.
The Input hypothesis is Krashen's attempt to explain how the
learner acquires a second language. In other words, this hypothesis is
Krashen's explanation of how second language acquisition takes place. So, the
Input hypothesis is only concerned with 'acquisition', not 'learning'.
According to this hypothesis, the learner improves and progresses along the
'natural order' when he/she receives second language 'input' that is one step
beyond his/her current stage of linguistic competence. For example, if a
learner is at a stage 'i', then acquisition takes place when he/she is exposed
to 'Comprehensible Input' that belongs to level 'i + 1'. Since not all of the
learners can be at the same level of linguistic competence at the same time,
Krashen suggests that natural communicative input is the key to designing a
syllabus, ensuring in this way that each learner will receive some 'i + 1'
input that is appropriate for his/her current stage of linguistic competence.
Finally, the fifth hypothesis, the Affective Filter
hypothesis, embodies Krashen's view that a number of 'affective variables' play
a facilitative, but non-causal, role in second language acquisition. These
variables include: motivation, self-confidence and anxiety. Krashen claims that
learners with high motivation, self-confidence, a good self-image, and a low
level of anxiety are better equipped for success in second language
acquisition. Low motivation, low self-esteem, and debilitating anxiety can
combine to 'raise' the affective filter and form a 'mental block' that prevents
comprehensible input from being used for acquisition. In other words, when the
filter is 'up' it impedes language acquisition. On the other hand, positive
affect is necessary, but not sufficient on its own, for acquisition to take
place.
The Role of Grammar in Krashen's View
According to Krashen, the study of the structure of the
language can have general educational advantages and values that high schools
and colleges may want to include in their language programs. It should be
clear, however, that examining irregularity, formulating rules and teaching
complex facts about the target language is not language teaching, but rather is
"language appreciation" or linguistics.
The only instance in which the teaching of grammar can result
in language acquisition (and proficiency) is when the students are interested
in the subject and the target language is used as a medium of instruction. Very
often, when this occurs, both teachers and students are convinced that the
study of formal grammar is essential for second language acquisition, and the
teacher is skillful enough to present explanations in the target language so
that the students understand. In other words, the teacher talk meets the
requirements for comprehensible input and perhaps with the students"
participation the classroom becomes an environment suitable for acquisition.
Also, the filter is low in regard to the language of explanation, as the
students" conscious efforts are usually on the subject matter, on what is
being talked about, and not the medium.
This is a subtle point. In effect, both teachers and
students are deceiving themselves. They believe that it is the subject matter
itself, the study of grammar, that is responsible for the students"
progress, but in reality their progress is coming from the medium and not the
message. Any subject matter that held their interest would do just as well.
References
Crystal, David The Cambridge Encyclopedia of Language.
Cambridge University Press, 1997.
Krashen, Stephen D. Principles and Practice in Second
Language Acquisition. Prentice-Hall International, 1987.
Krashen, Stephen D. Second Language Acquisition and Second
Language Learning. Prentice-Hall International, 1988.