Environmental Engineering Reference
In-Depth Information
representation of the fingertips provided greater luminance contrast. All other conditions
either had a low contrast representation (FV) or no representation at all (VPV, VMO, NV).
Therefore, the quality of the visual representation, specifically the luminance contrast, may
serve as a means to further reduce task demands and uncertainty.
Fig. 6. Effect of visual condition on average peak grasp apertures (error bars show ±SE): A)
Children F
4,44
=3.061,p=0.102 B) Young adults F
4,44
=10.011,p<0.001 C) Middle age adults
F
4,44
=4.144 p=0.022 D) Senior adults F
4,44
=1.207,p= 0.320. For young and middle age adults,
aperture in FVC was significantly smaller than in NV. For children and seniors FVC also
had the smallest mean aperture, although this did not reach significance at the p<0.05 level.
Also of note is that in young adults, FV and VPV also had significantly smaller apertures
than NV. Note the general lack of visual condition effect among seniors. Adapted from
(Grabowski & Mason, 2011).
To summarize, there are a few key findings from these two studies. First, young adults were
quite adept at utilizing limited visual feedback for the control of precision grasp tasks in
virtual environments. In contrast, senior adults could not make use of limited visual
feedback and tended to rely on a feed-forward strategy. While this strategy allowed the
older adults to be successful with the experimental task, it may limit the nature of their
interactions in such environments when tasks become more complex. Children and senior
adults both appeared to make compensatory adjustments in their motor planning for the
demands of the experimental task, however they involved different components of the
movement. Children altered the transport of their hand in space by using lower peak
velocities. Senior adults used a very large grasp configuration to compensate for task
uncertainty. Finally, aperture results indicated that there could potentially be some
enhancement in performance when augmented feedback about the hand (i.e. the crude
finger representation) contrasts at least moderately with the background environment. This
