What determines limb selection for reaching? /
While motor dominance appears to drive limb selection for reaching movements at the midline and ipsilateral (dominant) side, this study examined the possible attentional factor(s) that influence limb choice in contralateral space and, more specifically, which factor(s) from those associated with obj...
| Main Author: | |
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| Format: | Thesis Book |
| Language: | English |
| Published: |
[Place of publication not identified] :
[publisher not identified] ;
2000.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=731990101&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | While motor dominance appears to drive limb selection for reaching movements at the midline and ipsilateral (dominant) side, this study examined the possible attentional factor(s) that influence limb choice in contralateral space and, more specifically, which factor(s) from those associated with object proximity, comfort, and a hemispheric bias for reaching with the hand on the same side as the stimulus. Right- handed university students participated in two experiments. Experiment I was designed to distinguish between object proximity and a hemispheric bias by comparing perceived and actual reaching in two conditions: arms crossed and uncrossed. The question was would subjects program selection based on proximity; thereupon keeping the arms crossed or would they uncross the arms to reach ipsilaterally, lending support for a bias. A second question explored the possibility that perceived and actual responses might differ. Experiment II was to examine the role of comfort in limb selection using two tasks. First, subjects reached for a cube under two conditions: single and multiple-degree-of-freedom (df) movements. If subjects continued to reach ipsilaterally when responses required only 1-df movement, the comfort factor could be eliminated. For the second task, right hand reaches were videotaped and analyzed as a 1- or multiple-df movement. If the location of the transition from a l-df to a multiple-df reach was the same location where subjects switched hands in Task 1, the comfort hypothesis would have more credence. Experiment I results revealed a trend favoring object proximity as the controlling factor in responses to contralateral stimuli. Subjects preferred to keep the arms crossed in order to reach with the hand closest to the stimulus, thus eliminating the bias effect. In Experiment II, comfort was eliminated when subjects continued to prefer tile contaminant hand, even though they were able to reach with the dominant hand at all positions using only a 1-df movement. It appears that the proximity between the hand and the stimulus is the dominant factor driving limb selection in contralateral hemispace. A secondary finding worthy of further investigation revealed a conflict between perceived and actual movement while the arms were crossed. |
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| Item Description: | Vita. "Major Subject: Kinesiology". |
| Physical Description: | x, 127 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 92-101). |