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.

g. Are express saccades generated when the pursuit and vergence systems are co-engaged?

In everyday life the saccadic, vergence, and pursuit systems act in concert. To determine whether express saccades can be generated under such conditions, in one set of experiments the targets, ap.pearing singly, were set into motion when they appeared and in another set of experiments they appeared at various depths relative to the animal. The results shown in Figure 36 establish the fact that express saccades continue to be generated when the pursuit and vergence systems are engaged.