- System-centred approaches consider language as an object in itself, and one which can be studied from different angles according to the various strata of the language system, for example, sounds and groups of sounds, graphical signs and groups of graphical signs, lexical unities, syntactic entities, sentences, and discourse. They can involve both synchronic and diachronic dynamics, concern the disciplinary contributions of philology, grammar, linguistics (considered as language science) and the specialisation thereof, for example, phonetics, phonology, lexicology, semantics and morphology, and are related to sciences such as semiotics, anthropology and sociology.
The scientific target here is the mechanics of the language system: the way it functions and its evolutions.
- Ability-centred approaches focus on the mechanisms of language processing on an individual basis, stem from diverse functional angles (i.e. aspects of cognitive control, perception, production, etc.), and can take into account different types of phenomena (sound and graphic production, biophysical signals, macroscopic behaviour, etc.).
The scientific target here is the person, their communicative functioning and the evolution of this.
- Speech acts involve all identifiable modalities (production, reception, interaction and mediation), both in writing and orally. They can occur within various communication contexts, for example, in laboratories, families, care institutions, the workplace, prisons, and schools. They also occur under various types of pressure, including cognitive load, time pressure and adverse conditions of communication, stress, and mood fluctuations, all of which can have an influence on speech. They can be delivered by speakers with or without a disability (acquired, functional and/or developing congenital diseases) and also by mono- or multilingual speakers using their first, second or third language. In the latter case, the speech acts can take place within or outside a multilingual environment, and can have been the object of specific procedures of linguistic planning. The context of use can also be static (where language is considered stable) or dynamic (referring to language acquisition, development, rehabilitation and attrition).