For an English teacher it is very important to depend on the work done by linguists and theoreticians while teaching the language.It helps the teacher to find the proper acceptable methods and approaches to guide the lessons so that the learning process would be effective.A modern approach to language learning is based on
two basic theories: behaviourist and cognitive theories of language. Both of these
theories explane language learning and present different
Behaviourists consider language learning as a process of conditioning
and the expected goal in learning is achieved by a series of stimulus and
responses. According to this learning happens because of the relationship between stimulus and learners responces to it.That is why the learner´s activity during the lesson is highly important-when a learner gives expected responce only then he has learned.This theory was very popular among linguists in the middle of the last century, as the result many teaching publications appeared based on this theory.
The behaviourist approach to language learning grew out of the belief that students could learn a second language by being taught to produce the correct “response” to the appropriate “stimulus”. The student would then receive either instant positive or instant negative “reinforcement” in the shape of either correction or praise from the teacher.(http://www.esl-lounge.com/blog/165/the-behaviorist-approach)
As for cognitive theorists,they consider that a learner has a cognitive structure into
which any new learning is absorbed. Cognitive theory also can be called ‘mentalistic’
because all cognitive interpretation of language learning rests upon the neuropsychological base of thought, a learner understands a new input and then connects it with the inputs and experiences which are familiar to him already.(https://explorable.com/cognitive-learning-theory)
Teaching English as a foreign language it is important to mention that learners acquire the language by combining different approaches and theories.The combination of different methods makes a good language teacher therefore the teacher´s task is to observe and notice what learning theories work better for different tasks and students.