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During a unimanual grip selection task in which people pick up a lightweight dowel and place one end against targets at variable heights, the choice of hand grip (overhand vs. underhand) typically depends on the perception of how comfortable the arm will be at the end of the movement: an end-state comfort effect. The two experiments reported here extend this work to bimanual tasks. In each experiment, 26 right-handed participants used their left and right hands to simultaneously pick up two wooden dowels and place either the right or left end against a series of 14 targets ranging from 14 to 210 cm above the floor. These tasks were performed in systematic ascending and descending orders in Experiment 1 and in random order in Expiment 2. Results were generally consistent with predictions of end-state comfort in that, for the extreme highest and lowest targets, participants tended to select opposite grips with each hand. Taken together, our findings are consistent with the concept of constraint hierarchies within a posture-based motion-planning model. 相似文献
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The influence of a baseball glove on the positioning and grasping components of one-hand catching was studied under both vision impaired and unimpaired conditions. Skilled softball and baseball players (N = 20) caught tennis balls barehand and softballs with a fielder's glove. In half of the trials, a screen positioned alongside the subject's head blocked vision of the catching hand. All trials were videotaped and errors were categorized by type (position or grasp). Results indicated that with the glove performance was essentially perfect, regardless of the screen condition. Barehand grasping performance, however, was affected by the subject's inability to see his hand to a much greater extent than barehand positioning. We argue that the baseball glove functions to reduce both the positioning accuracy requirements and the grasp timing requirements in simple catching. Peripheral vision of the limb, however, is necessary for controlling the barehand grasp phase. 相似文献
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Fischman Gustavo 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1998,44(2-3):191-213
In the past two decades Latin American governments have carried out dramatic social and economic transformations. The application of different programs of structural adjustment and decentralization has promoted deep changes, not only in the economic and social arenas, but also within the educational systems. The dominant tendency is to look for all the answers to educational problems in the realm of the "free market". However, contrary to what this situation may suggest, practitioners of "popular education" in the region have not lost all their vitality. This paper explores the challenges and possibilities of popular education by examining the educational field after the application of structural adjustment programs, presenting a critique of Gramsci's model of the organic intellectual as understood by many within popular education, and offering the specific example of a popular education workshop in Argentina. 相似文献
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Adalbjornsson CF Fischman MG Rudisill ME 《Research quarterly for exercise and sport》2008,79(1):36-41
The end-state comfort effect has been observed in recent studies of grip selection in adults. The present study investigated whether young children also exhibit sensitivity to end-state comfort. The task was to pick up an overturned cup from a table, turn the cup right side up, and pour water into it. Two age groups (N = 20 per group) were studied: preschool children (2-3 years old), and kindergarten students (5-6 years old). Each child performed three videotaped trials of the task. Only 11 of the 40 children exhibited the end-state comfort effect, and there were no differences between age groups. Results revealed the emergence of five different performance patterns, none of which were consistent with sensitivity to end-state comfort. The findings have implications for the advance planning of manual control in young children. 相似文献