The Neural Control of Visually Guided Eye Movements
D. Temporal Factors in Visually Guided Saccadic Eye Movements
          1. The conditions under which express saccades can and cannot be generated.

In the second experiment the fixation spot and the targets used were always kept at the same location on the monitor. Data were collected with the monitor placed at various eccentricities thereby displacing the orbital position of the eye but leaving the relative position of the targets on the monitor and the vectors generated constant. Figure 38 plots the frequency of express saccades so generated. As eccentricity was increased, the frequency of express saccades declined for saccades to more eccentric positions but increased to less eccentric ones. However, the overall frequency of express saccades remained quite constant. Thus it appears that what is coded for express saccade generation is the saccadic vector, not the position of the targets in space and not the orbital positions of the eye.