8 leading theories in second language acquisition

Theories in language acquisition - illustration image

Second language acquisition (SLA) is a complex and multifaceted process that has long fascinated professionals across domains including linguistics, psychology, neuroscience and education. Their aim has been to understand how people who already know one language can best learn a second. Over time, a number of theories have been developed to explain the process. This blog post delves into eight of the most prominent second language acquisition theories, provides a concise overview of their fundamental tenets and outlines how language educators could use the theories in their own language classrooms.

At this point, it is important to note that the theories included below are not mutually exclusive. Considering the challenges involved in learning a new language, most language educators will draw on multiple theories in their language teaching approaches to deliver the best results for their students. Of course, individual learners may also benefit from different approaches based on their own learning circumstances and preferences.


1. Universal Grammar (UG)

First proposed by Noam Chomsky, UG argues humans are born with an innate ability for language and that there is a universal grammar that underlies all languages. This language acquisition device (LAD) is a mental blueprint that guides language learning and which enables infants to acquire and produce language.

Practical steps for use in your classroom:

  • Expose L2 learners to a wide variety of authentic language materials.
  • Encourage exploration and discovery of language patterns rather than explicit rule learning.
  • Employ a communicative approach that emphasises the underlying structure and patterns of the target language.
  • Encourage learners to compare and contrast the target language to their native language, highlighting similarities and differences in grammar and syntax.


2. Input Hypothesis

Developed by Stephen Krashen, the input hypothesis asserts that comprehensible input, or language input that is slightly beyond the learner’s current level of proficiency, is the primary driver of second language acquisition. This theory highlights the importance of exposing learners to meaningful and understandable target language content.

Practical steps for use in your classroom:

  • Use contextually rich and meaningful materials, such as stories, videos, and real-life situations. Take care to match language complexity to match learners’ abilities.
  • Utilise authentic materials such as news articles, songs, movies, and conversations with native speakers to enhance engagement and understanding.
  • Prioritise listening and reading activities and incorporate pre-reading and pre-listening activities to activate learners’ schemata and enhance comprehension.


3. Interaction Hypothesis

This theory of second language acquisition argues that meaningful interaction between L2 learners and native speakers (or proficient second language users) is a vital component of second language acquisition. First documented by Michael Long in 1976, the theory also highlights the importance of collaborative problem-solving in supporting language development.

Practical steps for use in your classroom:

  • Group activities, pair / peer interaction (e.g role plays) and collaborative projects should be encouraged.
  • Discussions and debates in small and large groups help to promote language use in meaningful contexts.
  • Consider how opportunities for language interaction can be maximised outside of the classroom.


4. Output Hypothesis

In 1995, Merrill Swain proposed the output hypothesis, which suggested that the process of producing language, both in written and spoken forms, played a crucial role in second language acquisition. This theory clearly emphasises the importance of giving learners the opportunities to actively use the target language.

Constructive feedback on any language output helps learners to notice gaps in their knowledge and is clearly vital to support students’ improvement. This is, of course, also true for all of the other theories outlined.

Practical steps for use in your classroom:

  • Provide ample opportunities for learners to produce the target language through writing, speaking, and presentation tasks.
  • Offer feedback on learners’ output, focusing on both accuracy and fluency.
  • Incorporate self-correction exercises to encourage learners to monitor their own language production and identify areas for improvement.


5. Sociocultural Theory (SCT)

This theory emphasises the role of social interactions and key cultural contexts as a vital force in shaping and driving language development. SCT, as pioneered by Lev Vygotsky and expanded upon by Michael Bakhtin, views language acquisition principally as a social and culturally-situated process. The real-world application of the target language and collaboration / group activities is therefore to be prioritised.

Practical steps for use in your classroom:

  • Create a classroom culture that values diversity, different cultural inputs and collaboration.
  • Integrate culturally authentic materials and activities to promote wider understanding and appreciation of different cultures and belief systems.
  • Encourage learners to engage in collaborative tasks or projects that involve real-world applications of the target language.


6. Behaviourist Theory

Typically associated with B.F. Skinner, the behaviourist approach suggests that language learning is a result of habit formation through imitation, reinforcement, and conditioning. In this manner, learners are rewarded for correct responses and “punished” for incorrect ones.

This theory is therefore characterised by its emphasis on repetition and drilling to reinforce key vocabulary and grammar structures.

Practical steps for use in your classroom:

  • Use drill-and-practice activities alongside frequent repetition of core principles to help learners solidify their understanding.
  • Employ positive reinforcement techniques, such as praise, reward, and encouragement, to motivate learners and maintain their engagement.
  • Break down complex language tasks into smaller, more manageable steps to provide learners with a sense of accomplishment and progress.


7. Cognitive Theory

As the name suggests, cognitive theory focuses on the role of mental processes such as attention, memory and problem-solving in language acquisition. It proposes that learners actively build up their knowledge of a new language through analysis, synthesis and evaluation. Evidently educators should prioritise activities that engage and stimulate such cognitive processes.

Practical steps for use in your classroom:

  • Use visuals, graphic organisers and mind maps to aid understanding and memory.
  • Provide learners with opportunities to engage in meaningful cognitive activities, such as summarising texts, solving puzzles, and engaging in discussions.
  • Encourage learners to use metacognitive strategies, such as planning, monitoring, and evaluating their own language learning process.
  • Create a supportive learning environment that fosters risk-taking and experimentation, allowing learners to make mistakes and learn from them.


8. Affective Filter Hypothesis

Also part of Krashen’s work (as referred above in Input Hypothesis), this learning theory proposes that emotional factors, such as anxiety, motivation and self-confidence, can influence language acquisition. It argues that if learners experience excessive anxiety or negative emotions, their ability to process and learn new language input is hindered. The opposite is, of course, also true.

The clear recommendation here is that fostering a positive and low-anxiety learning environment is crucial for effective language acquisition.

Practical steps for use in your classroom:

  • Create a positive and supportive learning environment that minimises anxiety and promotes a sense of belonging.
  • Connect language learning to learners’ interests and goals to enhance engagement and motivation.
  • Encourage learners to set realistic goals for themselves and celebrate their achievements along the way.
  • Provide opportunities for learners to personalise their learning, connecting new language concepts to their own interests and experiences.

These 8 theories have significantly enriched our understanding of second language acquisition and the key drivers for language learning success. By incorporating these strategies into their teaching approaches, language educators can create engaging and effective learning environments that foster successful second language acquisition for all learners.


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