Fig. 3.

Average variable errors across subjects for two lighting conditions and two delays, viewed from above (A), from the right side (B), and perpendicular to the plane of movement (C). Ellipsoids represent the tolerance region containing 95% of responses (see Materials and Methods). Dark line segments indicate the direction of the major eigenvector computed for the tolerance ellipsoid. For movements in the dark, a pattern of major eigenvector rotations upward and away from the starting position emerges in the ensemble averages, in comparison to head-centered eigenvector directions seen in the light.