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.

b. Are express saccades produced right off in the exprimental situation described or does it take training for them to emerge?

Figure 31 shows the distribution of saccadic latencies to a target that appears at position 225/5 with the fixation spot at 0/0 after limited exposure to this arrangement and after the monkey has made many thousands of saccades to this target. Few express saccades are made initially as shown in the upper panel; after extensive traning, as shown in the lower panel, numerous express saccades are made. Thus the generation of express saccades appears to require extensive training.