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N Schepens

Publications and source records attributed to N Schepens.

3 recordsLinked to original sources

Learning an imposed timing in a sequential arm movement.

The possibility of learning an imposed timing in a sequential arm movement was investigated as such observations could have important implications for learning in sport. The experimental task was performed by 26 women and 19 men on a vertical digitizer and required a movement made of four segments, different in both length and direction. To impose a timing very different from a spontaneous one, the spontaneous temporal organization on this task had first to be characterized. Then, during the learning, visual and auditory information about the imposed timing was given to subjects on each trial. Analysis showed that subjects accurately learned the imposed timing; moreover, the learning was a discontinuous process. Finally, it was obvious that the learned timing could be transferred to a reversed spatial pattern.

Adult↗

Children's and adults' learning of a visuomanual coordination: role of ongoing visual feedback and of spatial errors as a function of age.

The role of ongoing visual feedback and of spatial errors in learning a target-aimed task was investigated in 6-, 8-, and 11-yr.-old children, and young adults. In each of the four age groups, 16 subjects were randomly assigned to one of three conditions of learning (either with or without vision of the limb or with vision of final spatial error). All the subjects were tested without vision of the limb before and after the learning session. Before learning, directional bias was larger for 8-yr.-old children and target undershooting was greater for adults. After learning with vision of final spatial error, amplitude and direction improved for all age groups. Nevertheless, directional accuracy during the learning session increased more slowly for children than for adults. After learning with vision of the limb, direction improved for 6- and 8-yr.-old children only, demonstrating a specific role of ongoing visual feedback during learning at these ages. Further, an analysis of movement paths suggests a poorer capability for integrating proprioception by children than by adults.

Adult↗

Children's development of reaching: temporal and spatial aspects of aimed whole-arm movements.

Age-related changes in movement time and spatial distribution of pointing errors were investigated using a whole-arm target-aimed task. 60 children (6 to 11 yr.) and 10 young adults were required to reach towards targets located on a vertical screen in four conditions: target lit for 4 sec. in light (1), in darkness (2), target lit for 200 msec. in light (3), in darkness (4). Accuracy was perfect in Conditions 1 and 2, with a significant increase of MT in Condition 2 between the ages 7 and 10. Accuracy decreased slightly in Condition 3 and strongly in Condition 4, despite a similar shortening of MT. In Condition 4 the subjects undershot the target position: horizontally from age 8 and vertically in all age groups, with an increase of vertical bias by girls at age 9. These results suggest age-related changes in computation of arm movement towards the target.

Adult↗