This document compares Stephen Krashen's Input Hypothesis from 1977 and Merrill Swain's Output Hypothesis from 1993 regarding second language acquisition. Krashen's hypothesis consists of five points including the idea that language is acquired through comprehensible input, while affective factors like anxiety can inhibit acquisition. Swain's hypothesis has three points and argues that language production is important for noticing gaps and modifying one's language. While the hypotheses differ on the importance of input versus output, the document concludes that both are needed to some degree and are more applicable to different learning goals like syntax versus vocabulary.

1. Input and Output Hypotheses; a Comparative Essay
Second language acquisition (SLA) has been an extensively discussed field
for the last 50 years. Up to date, several theories about second language acquisition
have been developed. Authors can vary from many places and many ages. The truth
is that as time changes, so the way to acquire a language does, which justifies the
fact that we can find several proposals when it comes to talk about SLA. One
interesting doctrine is Stephen Krashen’s Input Hypothesis, which was introduced
back in 1977 (Krashen, 1977), and Merrill Swain’s Output Theory which came out in
1993 (Swain, 1993). Both are the ideas being compared in this essay, but, in order
to decide how are they compared or contrasted, it is important to point out the main
ideas or structure of each one, presenting a systematic view below.
To begin with, Krashen’s theory, in contrast with Swain’s hypothesis, is made
up of five main points. However, it was not always like that, as it first came up as one
of the five theories, but over the time the term has come to refer to the five hypothesis
as a whole (Krashen, 1985). This five hypothesis includes first the Acquisition-
Learning process, which presents two independent ways of acquiring language, one
being at a subconscious level (acquisition), which is natural and intuitive, from which,
individual do not need to be aware. The other occurs at a conscious level (learning),
frequently in the form of language ‘rules’ or ‘grammar’. Second is the Natural Order
hypothesis, which presents the language as system that is acquired in a predictable
order. Thirdly is the Monitor hypothesis, which is about monitoring our own learning,
being conscious all the time of what we are doing, in other words, while the acquired
system produces the speech, the learned system checks what is being spoken.
Fourthly, is the Input Hypothesis, which claims that we acquire language in just one
way; by receiving an input (receiving skills), that input is said to be ‘comprehensible,
hence understandable to the learner. Lastly is the Affective Filter Hypothesis, which
argues that a learner must be disposed to learn in order to do it, for that he/she must
feel comfortable and also must not be forced to produce language if he/she does not
feel ready for that. A consequence of a learning who does not feel relaxed, would be
a high affective filter, blocking the receiving of input. These five theories build the
nowadays Krashen’s Input Hypothesis which is about to be compared with Swain’s
Output hypothesis presented below.
Compared to professor Krashen’s Input Hypothesis, Swain’s theory has only
three ideas (Swain, 1995). The noticing/triggering theory, which as in Krashen’s
monitor hypothesis, the learners are aware of their knowledge, but, in this case, it is
focused on monitoring mistakes, which triggers them to keep looking for the
adequate knowledge. With the use of this function, the learner can notice that there
are some problems to fix in order to move ahead. The next idea is The Hypothesis-
testing function, which states that, as Krashen also argues, at a conscious level
(Krashen, 1985), in which Swain proposes that the learner, during the process

2. creates his/her own hypothesis on how the language works, and tries them out along
the learning, resulting in feedback which can lead learners to modify or ‘reprocess’
their output (Swain 1995). The third idea refers to the metalinguistic (reflective)
function, which sees the language as a tool that leads to a reflection on the language
used by the teacher, peers and the student himself/herself (Vigotsky’s sociocultural
theory). When it comes to this theory, it is important to highlight the importance of
the meaning; which is not simply related to understand the meaning that the
transmitter sends to the receiver, but concerns a clear, precise coherent and
appropriate message. After finishing presenting both theories, it is time to make a
deeper comparison.
Moving forward, Krashen’s hypothesis claims that language input (listening
and reading) compose the main communicative process, from which we acquire a
second language (Krashen, 1982). For Krashen, in contrast with Swain, speaking
and writing skills will develop naturally in a learner as they are exposed through a
comprehensible input, losing importance to receiving skills. Such input is one level
more difficult than the current learner’s language level, represented by the formula I
+ 1 (Krashen, 1982) where ‘I’ stands for ‘input’. That is to say, if the second language
learner is adequately exposed to a comprehensible input, the output will be
generated spontaneously, in a natural way. Additionally, and as we have already
explained in the second paragraph, Krashen’s Affective Filter Hypothesis, proposes
that learners should not be forced to produce language (output) if they don’t feel
ready, as this would produce negative feelings developing a high affective filter
interfering with the learning. This is the way in which Krashen presents his idea of
the importance of the input, however, Swain’s thoughts are different.
On the other hand, Swain’s Output hypothesis states that the best way to
acquire a second language is through productive skills (speaking and writing). The
author of this hypothesis argues that thanks to the production of the language, the
learners can actually realize what they know or what they don’t developing
metacognition, or self-awareness of what is being produced. Swain introduces the
term gap to refer to what a learner wants to say but what he or she indeed says,
explaining the importance of producing to find this ‘gap’ so the student gets
motivated towards modifying their interlanguage in order to fill this gap. Also,
professor Swain presents the importance of producing language (output), in four
ways (Swain, 1993), which will serve as aid in SLA. First he presents the production
of the language as a chance for meaningful practice for the learners. The second
way in which producing language might serve in SLA, is that it may force the learner
to move from semantic processing to syntactic processing (Swain, 1993). The third
way is about getting the learners learn formulating their own hypothesis, which are
instantly tested and improved through production of language. Lastly the fourth one
is closely related to the third one, but including peers and the people included in the
communicative environment. Consequently, we can clearly see how the author who

3. issued this theory totally stands for the output over the input, however, can they be
related?
Although different, we can relate Krashen and Swain’s hypotheses. I hold the
position that both theories are right, but at the same time incomplete. It is true the
fact that, as the input theory hypothesizes, after some training with receiving skills,
learners will strengthen their productive competences, but it is not accurate to say
that it will happen half of the time, therefore comprehensible input is essential in SLA,
but not enough. On the other hand, Swain’s doctrine about producing language to
foster SLA, is also partially accurate, however, and in contrast with Krashen’s
proposal, it is also true that student shouldn’t be forced to produce language,
jeopardizing their motivation to learn a second language, losing it to the fear of
failure.
As a final conclusion we can argue that at the time of complementing the
ideas, we might say that indeed a certain amount of comprehensible input is
necessary before producing any kind of output. Furthermore, both theories are
suitable to different purposes, for example, if the focus is in syntax , the most
adequate theory to use is Swain’s Output Hypothesis, however, if we want to achieve
vocabulary knowledge, Krashen’s input theory will serve in a better way. Finally, and
after having analysed both hypotheses, I can strongly state that both are open to
further develop, and specialized in specific times in specific context with specific
goals.

4. References
Krashen, S. (1985). “The Input Hypothesis. Issues and Implications” pp. 77 – 109.
Krashen, S. (1977). "Some issues relating to the monitor model". Washington, DC.
Krashen, S. (1982). “Principles and Practice in Second Language Acquisition”,
University of Southern California.
Swain, M. (1993), “The Output Hypothesis” pp. 158 – 163.
Swain, M. (1995), “Three functions of output in second language learning”.