The Neural Control of Visually Guided Eye Movements
D. Temporal Factors in Visually Guided Saccadic Eye Movements

4. Inferences

The inferences drawn from the work described are the following:

• The bimodal distribution of saccadic latencies obtained to visual targets is a product of strict laboratory conditions. Extensive training is required for their production.

• Disengaging fixation, which is an active process, is essential for express saccade generation.

• What is learned for express saccade generation is the saccadic vector, not the position of the targets in space and not the orbital position of the eye.

• The short-duration fixations that occur under natural viewing and correspond to the latencies with which express saccades are produced do occur but may not involve the same neural systems that are utilized for the generation of express saccades in the laboratory.

• The express saccade phenomenon does not reflect on systems that have evolved to enable organisms to respond quickly and expetitiously to selective stimuli appearing suddenly in the visual scene.

• Pre-cuing is effective in increasing express saccade generation when single targets are used but not when several targets appear at the same time. The latter may be due to the fact that the multiple target condition involves decisions about where not to look.