The Influence of Practice on Lip/Jaw Kinematics during Dual-Task Performance
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Performing two tasks concurrently is the rule rather than the exception for human activity. Performance of two tasks simultaneously can lead to execution costs or interference, which are also said to minimize with practice. Recent theories debate as to the cause of this interference. One theory hypothesizes that the dual-task performance is limited by the Central Cognitive Bottleneck, which suggests that when a person is responding to the first stimulus they cannot respond to a second stimulus until they have finished the first. The opposing theory, Adaptive Executive Control, hypothesizes that experienced performance uses procedural knowledge in the form on condition-action production rules (i.e. knowing how to) (Schumacher, Seymour, Glass, Fencsik, Lauber, Kieras, & Meyer, 2001). The latter theory states that the two tasks can occur in parallel, whereas the first theory suggests that the two tasks must occur one after the other. The goal of our study is to acquire data, from eight healthy, young English-speaking adults with the intent of testing the two theories within the domain of speech production. Lip/Jaw kinematics will be observed across practice sessions and measured during the two experimental sessions, for both the single and dual-task conditions. Te experiments consist of 5 sessions, session one consist of pure homogenous single-task, sessions two – four consist of both pure homogenous single-tasks and dual tasks (concurrent presentation of both stimuli), and session five consists of dual-task performance only. The independent variables for this study include the tasks, an auditory stimuli paired with a verbal response and a visual stimuli paired with a manual response, and practice. The dependent variables for this study include velocity, displacement, word duration, spatiotemporal index, reaction time, and error rates of responses to compare the influence of practice on both single and dual-tasks. A repeated measures analysis of variance (ANOVA) will be completed, noting the main effects of task and practice.