UC San Diego

This dissertation explores the phenomenon of co-sign mouthings in ASL. Mouthings are silent movements of the mouth that are derived from English and accompany manual signs, yet it has not been established how closely mouthings resemble voiced speech. Furthermore, it is unclear how mouthing productions are influenced by interarticulatory coordination between the mouth and hands. These two issues are investigated in a series of three experiments. Chapter 1 lays out the theoretical groundwork of the form and function of oral articulations in sign language as well as reviews previous findings concerning hand-mouth motoric interactions. Chapter 2 investigates the factors that contribute to hand-mouth coordination for mouthed fingerspelled items produced by Deaf participants, using a motion capture recording paradigm (Experiment 1). Results indicate that both spatial and temporal coupling are greater for hand-mouth combinations that are shorter rather than longer and in which the two articulators share the same number of movements. Direction of the articulators' movements, however, did not affect coordination. Moreover, items mismatched in number of movements coordinate by one articulator's single movement lengthening its duration to match the temporal domain of the other articulator's two movements. Chapter 3 extends the previous experiment by investigating the same issues but during the production of mouthed lexical signs, with the inclusion of a hearing non -signer comparison group (Experiment 2). Results suggest that while Deaf participants initiate the movements of the hand and mouth simultaneously, hearing participants begin articulating the manual component before the mouthing. However, Deaf and hearing groups do exhibit similar effects of item length. Chapter 4 again uses motion capture to investigate the motor representation of mouthings as they compare to speech in both Deaf signers and hearing non-signers through a comparison of mouth movement profiles (Experiment 3). Results suggest that Deaf signers use a single shared representation to produce mouth movements for both co-sign mouthings and voiced speech. Chapter 5 considers the findings revealed in the experimental data and offers a general discussion of the major issues that underlie the production, representation, and interarticulatory coordination of mouthings in ASL. Finally, suggestions to extend this work and apply its findings to new domains are offered