Akira Omaki, Ph.D. - US grants

Language learners must identify linguistic properties that differ across languages in the language input that surrounds them, and much recent research has explored the potential importance of distributional regularities in the language input for successful learning. However, other recent findings on child sentence understanding have shown that children's immature language comprehension system is prone to mis-parsing of the input. This raises the possibility that informative distributional information might be missed by the learner: if a child misanalyzes sentences in the input, then the true input distribution from the perspective of adults and researchers may be different from the 'intake', i.e., the effective input distribution that feeds into the language learning mechanism. This project investigates this issue through studies of incremental sentence parsing and reanalysis in question constructions in English and Japanese.

Under the direction of Dr. Colin Phillips and Dr. Jeffrey Lidz, Mr. Akira Omaki will conduct studies using eye-tracking, question-after-story and truth value judgment measures in English and Japanese in order to assess a) whether children, like adults, make early commitments to the interpretation of questions ('active dependency processing'), and b) whether children are able to successfully reanalyze in cases where their initial interpretation turns out to be incorrect. The experimental findings will be supplemented with a corpus analysis and a computational modeling study will be combined with the experimental findings, in order to generate an estimate of how the distribution of wh-question constructions appears from a child's perspective. A novel feature of the project is that it combines experimental and corpus-based approaches to gain an understanding of how children's language comprehension system might lead them to apprehend distributional regularities that do not correspond to what is actually present in their input. Thus, one broader impact of the project is that it could have important implications for any research that emphasizes the role of distributional regularities in the language acquisition process. A second broader impact of the project is that it will help to establish new partnerships for language acquisition research on Japanese, based on developing institutional connections with preschools, and will facilitate future international collaborations on comparative language acquisition studies.

This INSPIRE award is partially funded by the Linguistics Program and the Perception, Action & Cognition Program in the Division of Behavioral and Cognitive Sciences in the Directorate for Social, Behavioral & Economic Sciences; by the Robust Intelligence Program in the Division of Information & Intelligent Systems in the Directorate for Computer & Information Science & Engineering; and by the Algorithmic Foundations Program in the Division of Computer and Network Systems in the Directorate for Computer & Information Science & Engineering.

Discrete, combinatorial systems of structured symbols permeate human cognition in domains such as language, motor control, complex action planning, learning, and higher-level vision. Nonetheless, the computational apparatus that the brain exploits is based on continuous, activation-based propagation of information through complex networks of neurons. A fundamental problem of the cognitive sciences is how to integrate gradient, continuous neural computation with the discrete combinatorial dimension of cognition. The solution to this puzzle will provide a deeper understanding of the mind and may also serve as the basis of a new generation of computing systems capable of authentically brain-like behavior.

Under the direction of Dr. Smolensky, the research team will develop an approach to this puzzle by exploring and testing the predictions of their theory of Gradient Symbolic Computation (GSC) in the domain of language. Their efforts will include the development of the formal, mathematical foundations of GSC. In parallel, the PIs will develop a framework for modeling Gradient Symbolic Processing. To that end, the PIs will use computational modeling and experimental psycholinguistic studies of phenomena that typify the morpho-phonological, syntactic, and semantic characteristics of language and language processing.

The broader impacts of the work include the potential to transform general computing for future approaches to computer design, to provide innovations in computer language processing, and to empower major advances in our understanding of human language, its impairment in disease, and its learning and remediation. The project also strongly engages STEM education. Undergraduate, graduate, and post-doctoral researchers will all play key roles in highly interdisciplinary STEM research integrating experimental, theoretical, and computational methods. The new type of computation created will provide an integrative framework for developing courses bridging computation theory, psychology, and linguistics. Pedagogical materials developed in these courses will be made publicly available to facilitate undergraduate and graduate program development at other institutions.

Understanding how children learn to comprehend language as efficiently as adults do is a central goal for theories of both normal and abnormal language acquisition. Developmental research has shown that, while much linguistic knowledge develops in the first few years of life, children are not necessarily adept at quickly using this knowledge during real-time language comprehension. For example, as sentences unfold, adult listeners and readers are able to continuously predict how the sentences are likely to continue, based on their knowledge of language or the distribution of sentence structures. However, children's prediction mechanisms sometimes diverge from those of adults, and they must somehow develop adult-like predictive mechanisms during the course of language acquisition. Understanding this developmental process could lead to advances in the pedagogical techniques that aim to enhance language comprehension in children. This may also improve clinical intervention methodologies for adult patients with language disorders, whose comprehension mechanisms show similar characteristics to those of children's.

This project investigates the development and adaptation of filler-gap dependency processing mechanisms in children and adults. In comprehending questions like "What was Emily eating the cake with -- ?," adults incrementally complete the dependency by associating the dislocated wh-phrase "what" with the verb, but children wait to complete the dependency until after the verb and its object is encountered. The main hypothesis of this project is that language experience and distributional regularities in the input play a key role in the development and adaptation of predictive processes in filler-gap dependency completion. The motivation for this hypothesis is two-fold. First, it is well established in developmental psychology that distributional regularities can bootstrap children's cognitive and linguistic development. Second, much work in adult psycholinguistics research has argued that syntactic priming, a processing facilitation that results from repetitions of abstract syntactic structures, reflects an implicit learning mechanism that adapts the comprehension procedures in accordance with the recent language experience. Taken together, children's comprehension mechanisms may adapt to an adult-like mechanism based on a) a long-term accumulation of filler-gap dependencies that complete at the verb position, as well as b) syntactic priming of such filler-gap dependencies within an experimental session. Conversely, adults' comprehension mechanisms should also adapt to the child-like, conservative mechanism after exposure to filler-gap dependencies that are completed at a post-verbal position. To test these predictions, Dr. Omaki will conduct i) a corpus study that investigates the distributional patterns of English filler-gap dependencies in adults' conversations and child-directed speech, and ii) five eye-tracking experiments with children and adults that explore the time course of filler-gap dependency processing, as well as its interaction with priming sentences that are designed to create a bias towards the alternative dependency completion mechanism. As such, this project links questions and methodologies in two traditionally separate fields of adult psycholinguistics and language development.

In everyday language use, speakers are able to produce sentences effortlessly, weaving together multiple words while following complex grammatical rules. The ease with which sentences are produced has led to speculations that sentence production may not rely on executive functions such as inhibitory control. This project aims to test whether inhibitory control plays a role in grammatical production by focusing on subject-verb agreement 'attraction' errors. In English, the subject of the sentence agrees with the verb in number (e.g., "The lion is red," "The lions are red"). Attraction errors arise when the sentence contains a second noun with a different grammatical number than the subject noun, as in "The lion next to the birds ARE red." Understanding the role of inhibitory control in sentence production could provide key insights on how to evaluate and treat language impairments, as well as how to develop more effective pedagogical methods for children who produce non-adult-like syntactic structures. The proposed research provides opportunities to bring together undergraduate and graduate students in medical and cognitive science research, and the outcome of this research will be disseminated to the broader public through community outreach programs and aphasia rehabilitation projects.

This project uses two approaches to investigate whether subject-verb agreement errors are independent of executive (inhibitory) control. The first approach uses a combination of experimental techniques that manipulate inhibitory demand with advanced statistical modeling to test the contribution of different types of inhibitory control to the prevention of attraction errors. Second, the experiments are extended to 6- to 8-year-old children to investigate how the development of executive control abilities aligns with the developmental trajectory of agreement production abilities.