Onset times of visually guided saccades have a bimodal distribution. The faster type of saccades are termed `express saccades'. Ablation of the SC but not of the FEF makes express saccades disappear.⇒
The timing of correct pro-saccades has a bi-modal distribution. One class of pro-saccades happens very fast (express saccades), the others take a little longer.
Express saccades are thought of as reflex behavior. The reflex behind them is referred to as the 'visual grasp reflex'.
They are believed to be the result of a direct translation of a visual stimulus into a motor command.⇒