Figure 9.

Relationship between drift velocity and null positions in CD. Blue data points depict horizontal drift velocity. Horizontal drift velocity in CD is minimal at the null position, and increases with distance from the null. There is a reversal in the drift direction as the head orientation shifts from the right of the null to the left. This phenomenon is reflected in the change in the sign of the drift velocity. Red and green data points depict relationships between torsional and vertical drift velocities with horizontal head position. Axes were customized for each patient to most clearly demonstrate the size and direction of drifts.