Throughout the 20th century, structuralist and generative linguists have argued that the study of the language system (langue, competence) must be separated from the study of language use (parole, performance), but this view of language has been called into question by usage-based linguists who have argued that the structure and organization of a speaker’s linguistic knowledge is the product of language use or performance. On this account, language is seen as a dynamic system of fluid categories and flexible constraints that are constantly restructured and reorganized under the pressure of domain-general cognitive processes that are not only involved in the use of language but also in other cognitive phenomena such as vision and (joint) attention. The general goal of usage-based linguistics is to develop a framework for the analysis of the emergence of linguistic structure and meaning. In order to understand the dynamics of the language system, usage-based linguists study how languages evolve, both in history and language acquisition. One aspect that plays an important role in this approach is frequency of occurrence. As frequency strengthens the representation of linguistic elements in memory, it facilitates the activation and processing of words, categories, and constructions, which in turn can have long-lasting effects on the development and organization of the linguistic system. A second aspect that has been very prominent in the usage-based study of grammar concerns the relationship between lexical and structural knowledge. Since abstract representations of linguistic structure are derived from language users’ experience with concrete linguistic tokens, grammatical patterns are generally associated with particular lexical expressions.
Cognitive linguistics and morphology bear the promise of a happy marriage. Cognitive linguistics provides theoretical concepts and analytical tools for empirical analysis, while morphology offers fertile ground for testing hypotheses and refining core concepts. It is no wonder, then, that numerous contributions to the field of morphology have been couched in cognitive linguistics, and that morphological phenomena have figured prominently in cognitive linguistics. Cognitive linguistics is a family of closely related frameworks that share the idea that language should be analyzed in terms of what is known about the mind and brain from disciplines other than linguistics. Cognitive linguistics furthermore adopts a semiotic perspective, claiming that the raison d’êtreof language is to convey meaning. Another central tenet is the usage-based approach, the idea that grammar emerges through usage, which implies a strong focus on language use in cognitive linguistics. An example of how cognitive linguistics relates morphology to general principles of cognition is the application of general principles of categorization to morphology. Morphological categories are analyzed as radial categories, that is, networks structured around a prototype. Such category networks can be comprised of the allomorphs of a morpheme or be used to model theoretical concepts such as paradigm and inflection class. The radial category is also instrumental in analyzing the meaning of morphological concepts. Rather than assuming abstract invariant meanings for morphemes, cognitive linguistics analyzes the meaning of morphological phenomena through networks of interrelated meanings. The relationships among the nodes in a category network are analyzed in terms of general cognitive processes, such as metaphor, metonymy, and blending. The usage-based approach of cognitive linguistics manifests itself in the strong focus on frequency effects in morphology. It is argued that frequency is an important structuring principle in cognition, and that frequent forms have a privileged status in a morphological paradigm.
First-language acquisition of morphology refers to the process whereby native speakers gain full and automatic command of the inflectional and derivational machinery of their mother tongue. Despite language diversity, evidence shows that morphological acquisition follows a shared path in development in evolving from semantically and structurally simplex and non-productive to more complex and productive. The emergence and consolidation of the central morphological systems in a language typically take place between the ages of two and six years, while mature command of all systems and subsystems can take up to 10 more years, and is mediated by the consolidation of literacy skills. Morphological learning in both inflection and derivation is always interwoven with lexical growth, and derivational acquisition is highly dependent on the development of a large and coherent lexicon. Three critical factors platform the acquisition of morphology. One factor is the input patterns in the ambient language, including various types of frequency. Input provides the context for children to pay attention to morphological markers as meaningful cues to caregivers’ intentions in interactive sociopragmatic settings of joint attention. A second factor is language typology, given that languages differ in the amount of word-internal information they package in words. The “typological impact” in morphology directs children to the ways pertinent conceptual and structural information is encoded in morphological structures. It is thus responsible for great differences among languages in the timing and pace of learning morphological categories such as passive verbs. Finally, development itself is a central mechanism that drives morphological acquisition from emergence to productivity in three senses: as the filtering device that enables the break into the morphological system, in providing the span of time necessary for the consolidation of morphological systems in children, and in hosting the cognitive changes that usher in mature morphological systems in both speech and writing in adolescents and adults.