Chapter 2. Prehension

180 THE PHASES OF PREHENSION
h
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v)
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v
700 -
600 -
4001
140r
0
50 100
Normalized time (%)
Figure 5.25 Kinematic profiles when grasping with pad
opposition using normal vision (NV) or with vision restricted to
the peripheral regions of the retina (PV) using specially designed
contact lenses. In all cases, maximum aperture is greater when
using peripheral vision than with normal vision. With peripheral
vision, the arm had stopped moving forward as subjects enclosed
the dowel and subjects adopted a tactile control strategy for
completing the grasp, compared to normal vision. (from Sivak,
1989; reprinted by permission from Sivak & MacKenzie, 1992).