Research in neurolinguistics examines how language is organized and processed in the human brain. The findings from neurolinguistic studies on language can inform our understanding of the basic ingredients of language and the operations they undergo. In the domain of the lexicon, a major debate concerns whether and to what extent the morpheme serves as a basic unit of linguistic representation, and in turn whether and under what circumstances the processing of morphologically complex words involves operations that identify, activate, and combine morpheme-level representations during lexical processing. Alternative models positing some role for morphemes argue that complex words are processed via morphological decomposition and composition in the general case (full-decomposition models), or only under certain circumstances (dual-route models), while other models do not posit a role for morphemes (non-morphological models), instead arguing that complex words are related to their constituents not via morphological identity, but either via associations among whole-word representations or via similarity in formal and/or semantic features. Two main approaches to investigating the role of morphemes from a neurolinguistic perspective are neuropsychology, in which complex word processing is typically investigated in cases of brain insult or neurodegenerative disease, and brain imaging, which makes it possible to examine the temporal dynamics and neuroanatomy of complex word processing as it occurs in the brain. Neurolinguistic studies on morphology have examined whether the processing of complex words involves brain mechanisms that rapidly segment the input into potential morpheme constituents, how and under what circumstances morpheme representations are accessed from the lexicon, and how morphemes are combined to form complex morphosyntactic and morpho-semantic representations. Findings from this literature broadly converge in suggesting a role for morphemes in complex word processing, although questions remain regarding the precise time course by which morphemes are activated, the extent to which morpheme access is constrained by semantic or form properties, as well as regarding the brain mechanisms by which morphemes are ultimately combined into complex representations.
The Japanese psycholinguistics research field is moving rapidly in many different directions as it includes various sub-linguistics fields (e.g., phonetics/phonology, syntax, semantics, pragmatics, discourse studies). Naturally, diverse studies have reported intriguing findings that shed light on our language mechanism. This article presents a brief overview of some of the notable early 21st century studies mainly from the language acquisition and processing perspectives. The topics are divided into various sections: the sound system, the script forms, reading and writing, morpho-syntactic studies, word and sentential meanings, and pragmatics and discourse studies sections. Studies on special populations are also mentioned. Studies on the Japanese sound system have advanced our understanding of L1 and L2 (first and second language) acquisition and processing. For instance, more evidence is provided that infants form adult-like phonological grammar by 14 months in L1, and disassociation of prosody is reported from one’s comprehension in L2. Various cognitive factors as well as L1 influence the L2 acquisition process. As the Japanese language users employ three script forms (hiragana, katakana, and kanji) in a single sentence, orthographic processing research reveal multiple pathways to process information and the influence of memory. Adult script decoding and lexical processing has been well studied and research data from special populations further helps us to understand our vision-to-language mapping mechanism. Morpho-syntactic and semantic studies include a long debate on the nativist (generative) and statistical learning approaches in L1 acquisition. In particular, inflectional morphology and quantificational scope interaction in L1 acquisition bring pros and cons of both approaches as a single approach. Investigating processing mechanisms means studying cognitive/perceptual devices. Relative clause processing has been well-discussed in Japanese because Japanese has a different word order (SOV) from English (SVO), allows unpronounced pronouns and pre-verbal word permutations, and has no relative clause marking at the verbal ending (i.e., morphologically the same as the matrix ending). Behavioral and neurolinguistic data increasingly support incremental processing like SVO languages and an expectancy-driven processor in our L1 brain. L2 processing, however, requires more study to uncover its mechanism, as the literature is scarce in both L2 English by Japanese speakers and L2 Japanese by non-Japanese speakers. Pragmatic and discourse processing is also an area that needs to be explored further. Despite the typological difference between English and Japanese, the studies cited here indicate that our acquisition and processing devices seem to adjust locally while maintaining the universal mechanism.
Laurie Beth Feldman and Judith F. Kroll
We summarize findings from across a range of methods, including behavioral measures of overall processing speed and accuracy, electrophysiological indices that tap into the early time course of language processing, and neural measures using structural and functional imaging. We argue that traditional claims about rigid constraints on the ability of late bilinguals to exploit the meaning and form of the morphology and morphosyntax in a second language should be revised so as to move away from all or none command of structures motivated from strict dichotomies among linguistic categories of morphology. We describe how the dynamics of morphological processing in neither monolingual or bilingual speakers is easily characterized in terms of the potential to decompose words into their constituent morphemes and that morphosyntactic processing is not easily characterized in terms of categories of structures that are learnable and those that are unlearnable by bilingual and nonnative speakers. Instead, we emphasize the high degree of variability across individuals and plasticity within individuals in their ability to successfully learn and use even subtle aspects of a second language. Further, both of the bilingual’s two languages become active when even one language is engaged, and parallel activation has consequences that shape both languages, thus their influence is not in the unidirectional manner that was traditionally assumed. We briefly discuss the nature of possible constraints and directions for future research.
Niels O. Schiller
Neurolinguistic approaches to morphology include the main theories of morphological representation and processing in the human mind, such as full-listing, full-parsing, and hybrid dual-route models, and how the experimental evidence that has been acquired to support these theories uses different neurolinguistic paradigms (visual and auditory priming, violation, long-lag priming, picture-word interference, etc.) and methods (electroencephalography [EEG]/event-related brain potential [ERP], functional magnetic resonance imaging [fMRI], neuropsychology, and so forth).
Valentina Bambini and Paolo Canal
Neurolinguistics is devoted to the study of the language-brain relationship, using the methodologies of neuropsychology and cognitive neuroscience to investigate how linguistic categories are grounded in the brain. Although the brain infrastructure for language is invariable across cultures, neural networks might operate differently depending on language-specific features. In this respect, neurolinguistic research on the Romance languages, mostly French, Italian, and Spanish, proved key to progress the field, especially with specific reference to how the neural infrastructure for language works in the case of more richly inflected systems than English. Among the most popular domains of investigation are agreement patterns, where studies on Spanish and Italian showed that agreement across features and domains (e.g., number or gender agreement) engages partially different neural substrates. Also, studies measuring the electrophysiological response suggested that agreement processing is a composite mechanism involving different temporal steps. Another domain is the noun-verb distinction, where studies on the Romance languages indicated that the brain is more sensitive to the greater morphosyntactic engagement of verbs compared with nouns rather than to the grammatical class distinction per se. Concerning language disorders, the Romance languages shed new light on inflectional errors in aphasic speakers and contributed to revise the notion of agrammatism, which is not simply omission of morphemes but might involve incorrect substitution from the inflectional paradigm. Also, research in the Romance domain showed variation in degree and pattern of reading impairments due to language-specific segmental and suprasegmental features. Despite these important contributions, the Romance family, with its multitude of languages and dialects and a richly documented diachronic evolution, is a still underutilized ‘treasure house’ for neurolinguistic research, with significant room for investigations exploring the brain signatures of language variation in time and space and refining the linking between linguistic categories and neurobiological primitives.