Linguists study the structure of language, ie sounds and meanings, and the grammar to which they relate, and they come together with psychologists who investigate how people acquire the structures and functions, and use them in speech and understanding. The work can be used to inform TEFL but also to help people with speech and language difficulties where some important component of communication may not have been acquired.

A knowledge of the difficulties of learning a foreign language is built into some degree courses in ESOL and Applied Linguistics by the syllabus including learning a foreign language from scratch in order to study the process by which we are taught and by which we learn (psycholinguistic study).