Input and output in second language acquisition

Learning English

This article deals with the input and output in second language acquisition. We will define concepts such as:

  • input vs output,
  • input, intake, and uptake,
  • and affordances vs emergence.

Input and output in second language acquisition

Input vs. output

The input refers to the processible language the learners are exposed to while listening or reading (i.e. The receptive skills). The output, on the other hand, is the language they produce, either in speaking or writing (i.e. The productive skills).

The input is multidimensional. It comes from the teacher, the coursebook, and the students themselves. It may also be derived from sources outside the confinement of the classroom (e.g. TV, podcasts, social media, etc.).

There is an interaction between the input and the output – between the receptive and the productive skills.

Figure 1 The input and the output in language teaching

As figure 1 shows, there is an interdependence between the input and the output. The four skills are interconnected to serve the learners’ interlanguage development.

The Input Hypothesis

The input that the students should be exposed to has to be comprehensible and should provide enough information to help them construct, consciously or unconsciously, their knowledge about the system. According to Krashen, comprehensible input is a prerequisite to language acquisition. It is more than enough for the internalization of the target language.  The condition that Krashen attaches to his Input Hypothesis is that the input should be pitched a little above the learner’s present state of competence. (i.e. Input + 1 or I + 1).

The output Hypothesis

On the other hand, Merrill Swain (1985) suggested that the input is not enough for language acquisition. According to her, there is a need for an Output Hypothesis. The learner needs to be pushed to produce language that is conveyed precisely, coherently and appropriately.  One argument in favor of pushing students to produce comprehensible messages is that the learners by doing so will notice the ‘gaps’ in their language knowledge, which will urge them to improve their existing interlanguage system. Another argument for Merrill Swain’s Output hypothesis is that, as Scott Thornbury (2010) suggests, when the learners are pushed to produce language in real time, they are ‘forced to automate low-level operations by incorporating them into higher-level routines’. This may contribute to the development of fluency and automaticity.

Input, Intake, uptake

As mentioned above, the input is the processible language that the learners are exposed to. It is the accessible data that is not necessarily understood yet.  It is only when the language data has been noticed, attended to and processed that the input becomes intake.  Sharwood Smith (1993) explains the difference between input and intake as follows:

“The input is the potentially processible language data which are made available, by chance or by design, to the language learner. That part of input that has actually been processed by the learner and turned into knowledge of some kind has been called intake.

It is important to note here that being exposed to a new language doesn’t mean that this input will necessarily become intake.   This input will be internalized and will become part of the learners’ knowledge only if it is noticed, attended to, processed and used in authentic situations. When language is learned in that way, it becomes uptake. 

Processible language.
Accessible language data.
Processed language.
Language noticed, attended to and processed.
Learned language.
Language that has become part of the learners’ interlanguage system.

Affordances and emergence

Traditionally, as mentioned above, the input refers to the language the leaners are exposed to. It should be slightly above the leaners level. Without comprehensible input, language acquisition does not take place. In the ecological approach to language teaching, instead of input and acquisition, new metaphors have been adopted, namely affordances and emergence.


Affordance is a term borrowed from ecology. It refers to what the environment offers to living things. It implies that organisms and the environment are complementary. As Scott Thornbury (2006) says:

“A leaf, for example, affords food for some creatures, shade for others, or building material for still others. It’s the same leaf, but its affordances differ, depending on how it is regarded, and by whom.”

In psychology, affordances are related to perception and action.  Menezes (2011) explains that:

“Animals, including humans, perceive what the niche offers them (substances, medium, objects, etc.), interpret the affordances and act upon them. Some actions are done automatically (e.g. drinking water) and others require complex cognitive processes (e.g.  finding the solution for a problem).” Menezes (2011, Page 2)


According to the Dogme approach to language teaching, learning opportunities offered by real talk in the real-world offer affordances for language to emerge rather than being merely acquired. As Leo Van Lier (2004, p 5) suggests emergence ‘happens when relatively simple elements combine together to form a higher-order system.’ Real interactions provide learning opportunities and it is only in this environment that language emerges.  This is a shift away from the traditional view of acquisition as a linear process.


Menezes V. (2011) Affordances for Language Learning Beyond the Classroom. In: Benson P., Reinders H. (eds) Beyond the Language Classroom. Palgrave Macmillan, London

Sharwood Smith, M. A. (1993). Input Enhancement in Instructed SLA: Theoretical Bases. Studies in Second Language Acquisition, 15, 165-179.

Swain, M. (1985) ‘Communicative competence: some roles of comprehensible input and comprehensible output in its development’. In Gass, S. and Madden, C. (Eds.)

Thornbury, S. (2006) An A-Z of ELT: A Dictionary of Terms and Concepts Used in English Language Teaching. Oxford, UK.: Macmillan Education.

Thornbury, S. (2010, July 11).P is for Push. Retrieved from


2 thoughts on “Input and output in second language acquisition”

  1. Pingback: Quando parlerà nella seconda lingua? - Piccoli Camaleonti

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