Doctoral Dissertation Research: Temporal and Spatial Properties of Speech at the Intersection of Production and Perception

New York University, New York NY

Investigators

Abstract

This project will address fundamental questions about the nature of the link between producing and perceiving speech. Existing experimental evidence points to the automatic and involuntary activation of the speech production system during speech perception. One goal of this project is to investigate what properties of speech are important in the perception-production link, a question that has not been systematically addressed. Speech production involves spatial properties, which speech articulators make what constrictions where in the vocal tract, and temporal properties, how those constrictions are arranged relative to one another in time. A series of cue-distractor experiments will be conducted to elucidate the conditions under which perception-production interactions occur in speech. Such interactions will be detected by measuring participants' reaction times to syllables produced (the cue) while another syllable is being perceived (the distractor). Subjects' reaction times will be compared in cases where the cue and distractor share spatial properties (for example, "pa" and "ba", which both involve a closing of the upper and lower lips) or temporal properties (for example, "ba" and "da", which both involve similar timing between the oral closure and vowel voicing). By analyzing the reaction times in such tasks, we will know if and how the involuntary activation resulting from the perceived distractor combines with the intended response to the visual cue. A second goal of the project is to develop a formal computational model of the perception-production link to account for and unify existing and new evidence for this link. Action and perception are known to be closely linked in behavior. This study investigates a specific instance of the link between action and perception in speech, thereby sharpening our understanding of the mechanisms underlying human communication. The project will provide an explicit computational model of the link between speech perception and production in specific experimental paradigms involving reaction time data. Such a model has not been developed despite many years of work on the topic of production-perception links. This model will be of value to the field because it will help to refine further predictions, and thus to design new experiments for sharpening our understanding of perceptuo-motor interactions in speech. A better understanding of the relation between perception and production may shed light on the ways in which disorders of one domain may be related to the disorders of the other. For example, individuals with non-fluent aphasia have difficulty with speech production but generally not with speech perception, and they have been shown to improve on certain production tasks through multi-sensory speech perception training. This research therefore has potential long-term benefits for revealing clinically relevant insights into the mechanisms of new treatment approaches. In addition, the methods used to collect and analyze response time data along with the computational modeling component in this project will add new important components in an existing training framework introducing undergraduates to integrative methods in theoretical and experimental linguistics.