The proposed program of research aims to investigate spoken language processing in both normal and disordered populations, focusing on the process of lexicalization (word retrieval). Specific topics include identifying the stages, their time course, and the units entailed during spoken language production, to better understand the mechanisms through which language is transformed into speech. This research will be conducted using cross-modal picture-word interference, an online method that uses reaction time methodology to obtain information about these processes. Participants name pictures while auditory stimuli are presented at varying intervals relative to the presentation of the pictures. By manipulating types of auditory stimuli and time of presentation, inferences can be made about the time course and processing mechanisms operating within the stages of spoken language production while they are unfolding in real time. Of particular interest are the stages from phonological encoding to motor programming, as the source of breakdown in several communication disorders, including stuttering, aphasia, apraxia of speech, and developmental phonologic impairments, has been associated with these stages. Due to the fleeting nature of these processing stages, research into the time course and processing mechanisms operating within and between these stages requires online methodology. Therefore, the program of study being proposed specifically aims to develop and apply online methods to examine these difficult-to-measure processes both among typical adults and individuals with the aforementioned communication disorders.
