Date of Award
Doctor of Philosophy (PhD)
Three experiments are reported that attempt to further our knowledge of the preparation and production of rapid sequential aiming movements. Specifically, these experiments examined possible reasons why in sequential aiming responses, the second movement segment (MT2) is consistently performed more slowly than first and third movement segments (MT1 and MT3). In the first experiment, participants struck 1, 2, or 3 targets in sequence without the benefit of visual feedback and without time stress to determine if MT2 is slowed due to a visually based on-line trajectory-correction process. The results showed that MT2 was not slower than MT1 under these condition. These findings suggest that either visual feedback or reaction time (RT) signal are partly responsible for slowing MT2 when present. The second experiment was conducted using a different avenue of investigation to address the issue of the use of visual feedback. Participants struck three targets in each of five conditions that differed with respect to the size of the first-target (1.5-10 cm diameter) under simple reaction time (SRT) paradigm. The results revealed that MT2 was not slower than the MT1 under the smallest first-target condition. These findings might suggest that lengthening MT1 allowed participants to correct movement error on-line during that segment. The final experiment investigated the possibility that MT2 is lengthened due to the on-line programming of the remainder of the response. Participants were required to perform three-, four-, five-, and six-segment responses within SRT and self-initiation paradigms. The results showed that under RT stress, MT2 was significantly slower than the other movement segments in all responses. However, in the self-initiation condition, MT2 was not significantly slower than MT1 apart from in the six-segment responses. These results suggest that rapid sequential aiming movements might be controlled by a hierarchically organized program that attempts to produce the response in two phases. The first phase of programming controls the first half of the response while the second half of the response tends to be programmed during the end of the execution of the first half of the response.
Yook, Dongwon, "The Preparation and Production of Rapid Sequential Aiming Movements in Motor Control." (1997). LSU Historical Dissertations and Theses. 6553.