Our lab investigates the nature of linguistic knowledge, how it is acquired and used, and its brain bases. We study spoken language and reading, in English and many other languages, in children and adults, using the methods of modern cognitive neuroscience: behavioral studies, computational models, large scale corpus analyses, and neuroimaging. Here are some of the issues that have our attention.
Language: How did it get that way?
Why do languages exhibit certain properties and not others? Languages exhibit statistical regularities at multiple levels; to what extent do they arise from our capacities to perceive, act, learn, and remember, coupled with the communicative functions of language?
The impact of language production on comprehension
The utterances we produce are the speech that others comprehend. Thus language production, a difficult task involving formulating, planning, and generating utterances, shapes language comprehension. This idea drives MacDonald’s Production, Distribution, Comprehension theory. Ongoing work in our lab is building on this framework to investigate how production and comprehension interact during language learning; language production as the basis for verbal working memory; and relations between language production and motor processes in humans and other species.
Statistical learning in language and reading
Spoken language evolved in the species and reading is a recent invention, yet both involve statistical learning over massive amounts of experiential data–Big Data for humans. Statistical learning can, potentially, explain how children manage to acquire spoken languages under the conditions they do, and how they subsequently learn the orthographic codes for language (in reading). Other species are also statistical learners but they neither speak nor read. What’s different about people?
The importance of language variation
Children’s early language experiences vary a great deal, with strong effects on learning to read. Differences in the quantity and variety of speech to young children have been associated with socioeconomic status (SES), but recent work suggests that this variability occurs across income levels and racial/ethnic groups. We have been examining another area in which language experience varies: differences between home and school dialects that may be an important factor in “achievement gaps” in reading.
Brain bases of reading and dyslexia
Research on the neural circuits that support reading, and neurodevelopmental anomalies that underlie dyslexia is progressing rapidly. Dyslexia is associated with anomalies in white matter tracts linking brain regions involved in language and orthographic processing. The impact is to produce noisier processing within and between regions, which slows learning and generalization. These anomalies are now being traced to susceptibility genes that affect brain development and to neurotransmitters that affect the integrity and reliability of neural processing. This research is converging on the source of the “noisy processing” first explored in the Harm and Seidenberg (1999) model of dyslexia.