In real life, divergence is frequently combined with vertical saccades. The purpose of this study was to examine the initiation of vertical and horizontal saccades, pure or combined with divergence.
We used a gap paradigm to elicit vertical or horizontal saccades (10 degrees), pure or combined with a predictable divergence (10 degrees). Eye movements from 12 subjects were recorded with EyeLink II.
The major results were (i) when combined with divergence, the latency of horizontal saccades increased but not the latency of vertical saccades; (ii) for both vertical and horizontal saccades, a tight correlation between the latency of saccade and divergence was found; (iii) when the divergence was anticipated, the saccade was delayed.
We conclude that the initiation of both components of combined movements is interdependent.