Cognitive Science; Psychology and Biology of Language
My research includes both empirical studies of linguistic behavior and theoretical analyses of the nature of language and its relation to mind and brain.
On the empirical side, I study specific modules of grammar from a variety of disciplines, much as biologists direct focus on a few "model organisms." Currently, our group is studying inflectional morphology: the ability to derive walked from walk or mice from mouse.
We are aiming for a unified theory and an extensive database of how the system works computationally, how it is learned, how it varies across languages, how it is used in language production and comprehension, and how it is represented in the brain.
In our human information processing laboratory, we conduct reaction-time and rating studies of how people produce and perceive inflected forms. We also borrow from, and contribute to, generative linguistic theory, examining interactions between syntax, morphology, and the lexicon in English and other languages.
We study people with neurological and genetic language and memory disorders (aphasia, Alzheimers, specific language impairment), gathering evidence on how the different cognitive and linguistic modules underlying morphology might dissociate. We study the development of inflection in childrens language, both by analyzing computer-based transcripts of spontaneous speech and by conducting experiments in child-care centers; these studies document childrens memorization and rule-deployment abilities and how they change over time.
On the theoretical side, I have used linguistic and psycholinguistic data to develop a comprehensive model of the acquisition of grammar and lexicon, and to analyze issues such as the role of symbolic and connectionist computational architectures in language, the evolution of human language, and the nature of conceptual categories.
Cognitive Processes: Perception, Comprehension, and Memory
The overall goal of the research program is to understand the very rapid processes involved in perceiving, comprehending, and remembering meaningful material such as words, sentences, or pictures. In contemporary theories of human information processing, such material passes through several stages of analysis as it is perceived and understood, and it is these stages and their interactions that we investigate.
Contrary to earlier assumptions, we have shown that a sentence can be understood and remembered when presented as rapidly as 12 words per second (using RSVP, rapid serial visual presentation). In contrast, a sequence of unrelated words (even if no longer than 4 or 5 words) is much more difficult to process: Although each word is apparently identified, immediate memory is grossly impaired. Just what are the processes that so rapidly convert a sentence (but not a string of words) into a stable representation?
Our work also encompasses more general questions about perception, memory, and language processing. Perceptual studies examine such theoretically significant phenomena as the mistaken perception of nonwords as words, repetition blindness (a new phenomenon discovered in my laboratory), the attentional blink in visual search, and the influence of prior and immediately following sentence context on the selective perception of words. Theoretical issues concerning short-term memory that we have addressed recently include the conceptual basis of "verbatim" recall and the representation of sentence syntax in such recall. Each of these studies contributes to the overall aim of understanding the stages of information processing that lead from a stimulus such as a word or sentence to a conceptual interpretation on and to a fleeting or stable memory.