Neural Processing of Morphological Structure in Speech Production, Listening, and Reading

Two of the most central and critical questions for the cognitive science of language are “what types of linguistic content are stored in memory?” and “how are they accessed?” Making progress on such questions requires not just experimental precision, but also theoretical precision. Theoretical linguistics can provide a detailed hypothesis space for experiments, whose results in turn can refine and expand linguistic theory. In this chapter, we review selected neurolinguistic research that has investigated the questions of storage and access as they pertain to morphological processing in speech production, listening, and reading. Our starting point is the refined conception of the morpheme in current linguistic theory. Our summary highlights the importance of conceiving of the external form of morphemes—be they phonological, orthographic, or motor—separately from their grammatical feature representations. This separation is central to current linguistic theories like Distributed Morphology, as well as in work on speech production and aphasia that depends on a distinction between lemmas and lexemes. The research described in this chapter demonstrates how grammatical knowledge helps determine how form representations are stored and accessed. In strong confirmation of linguistic theory, the research supports the separation of the a-modal abstract level of the morpheme or lemma from the various modality-specific form representations at the level of the morph or lexeme.