Abstract:
The present investigation examined the shape and variation of movement patterns associated with specific stress contexts. Movements of the lower lip were recorded using the Optotrak, a noninvasive system in which light emitting diodes are attached to the moving structure. Eight adult subjects produced versions of the utterance ``Buy Bobby a puppy'' that varied in stress. Initally, this utterance was produced with normal stress patterns. Then, a scenario was presented that elicited a contrastive stressed form (e.g., to stress ``Bobby,'' the subject responded to the utterances ``Don't buy Kathy a puppy. Buy Bobby a puppy.''). A standard technique in the analysis of kinematic data is to measure absolute values of peak velocity, displacement, and duration. Analyses revealed that, as expected, increased duration and amplitude occurred in stressed contexts. A second set of analysis procedures involved the evaluation of underlying movement patterns through time and amplitude normalization (i.e., collapsing absolute differences in duration and amplitude). Pattern recognition techniques were then applied, revealing that underlying patterning differed as a function of contrastive stress. [Work supported by NIDCD.]