How changing the frequency of visual information influences reaching and grasping performance in young and elderly women.

The purpose of this experiment was to compare and contrast the performance of young and elderly subjects on a reaching and grasping task with varied visual sampling to quantify the differences between the age groups and to determine if both are similarly influenced by limiting vision. Both young and elderly women (mean ages 21 and 70 years respectively) were asked to reach forward 20 cm to a dowel, grasp and transport it to a target located 20 cm further in front of them. While performing this task, subjects were wearing liquid crystal goggles which provided full vision of the target, or were strobed at 5, 6.25, 8.3, 12.5 or 25 Hz with a 25% duty cycle. Three-dimensional kinematic data from the hand, wrist, and dowel, and the forces applied in the horizontal and vertical direction were measured. The movement was subdivided into four phases; approach to the dowel, acquisition of the dowel, transport of the dowel, and release of the dowel. Changing the frequency of visual information did not differentially influence the reaching and grasping performance between the young and elderly subjects, with the exception of increasing the end point absolute constant error for the elderly subjects at the lower frequency conditions. The visual manipulation of providing intermittent vision as opposed to full vision constrained only how subjects released the opposition space. Elderly subjects demonstrated characteristic slowing during the setting up and use of the opposition space. It would appear that this slowing is a strategic adaptation that occurs with aging. In addition, elderly subjects set up the opposition space with a different program to afford a more cautious acquisition of the dowel. (Abstract shortened by UMI.)Dept. of Kinesiology. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1994 .D475. Source: Masters Abstracts International, Volume: 34-02, page: 0672. Adviser: Patricia Weir. Thesis (M.Hk.)--University of Windsor (Canada), 1994