This research is designed to demonstrate that naive speakers in a natural conversational situation reliably use prosody (loosely, the 'melody in speech') to structure the information they provide to listeners, and that listeners in turn make use of this prosodic structure to facilitate accurate recovery of the speaker's intended meaning. The broad objective of the research is to develop a psycholinguistic model of sentence comprehension in which prosody plays a fundamental role, often determining the syntactic and semantic interpretation assigned to a sentence. Participants in these experiments will play a cooperative board game that elicits semi-spontaneous productions of syntactically ambiguous sentences. The game involves two speakers, each with a game board the other cannot see, who must use to a limited set of scripted sentences to determine and communicate joint moves. Key utterances contain syntactic ambiguities such as the ambiguous prepositional phrase attachment in "Move the square with the triangle," (meaning either 'push the square with the triangle' or 'move the house-shaped piece.') To evaluate the production of prosody, players' speech will be recorded digitally and submitted to phonetic and phonological analysis. To evaluate the use of prosody in comprehension, the timing and fixation locations of players eyemovements will be recorded as they listen to and comprehend the conversation and implement the game moves. The experiments will use head-mounted eye tracking, a relatively new technology recently shown to be sensitive to prosodic and syntactic factors in experiments with isolated spoken sentences that refer to objects in the listeners' visual scene. The apparatus is ideal because it does not restrict movement, does not introduce an additional experimental task, and does not interrupt speaking or listening.
There are two novel aspects to this research. The first is that the game task focuses the participants' attention on the act of communication rather than on the process of reading, and can provide a more accurate picture of the use prosody in natural conversation between naive speakers. Recent work in language production has argued that speakers use prosody to disambiguate syntax only when they are aware of the ambiguity and are given explicit instructions, implying that although listeners can use prosody, they may have few opportunities to do so. However, speakers in these studies read sentences from notecards. Because the pragmatic goals of a reader differ dramatically from those of speakers in typical conversation, such tasks may misrepresent the nature and extent of prosodic disambiguation. The second is that the combination of the game task with head-mounted eyetracking technology will develop a much-needed novel method that will provide a temporally-precise, on-line measure of comprehension that can be used while comprehension is occurring as part of semi-spontaneous spoken discourse. This will allow Speer to investigate the issues concerning the relative influence of prosodic, syntactic, and situationally-determined discourse variables over the time course of sentence comprehension, which form the core of current work in modeling human language processing.
This POWRE grant will allow Speer to purchase a head-mounted system, providing her the opportunity to utilize this new methodology to which she currently has no access, and to conduct exploratory work necessary to begin a new line of inquiry. The availability of such methodology will greatly enhance her ability to provide empirical data relevant to important theoretical questions at the most basic level of her research program and thus will be highly important to the advancement of her career.
