saccade

thumb|Trace of saccades of the human eye on a face while scanning thumb|200px |Saccades during observation of a picture on a computer screen

In vision science, a saccade ( ; ; ) is a quick, simultaneous movement of both eyes between two or more phases of focal points in the same direction. In contrast, in smooth-pursuit movements, the eyes move smoothly instead of in jumps. Controlled cortically by the frontal eye fields (FEF), or subcortically by the superior colliculus, saccades serve as a mechanism for focal points, rapid eye movement, and the fast phase of optokinetic nystagmus. The word appears to have been coined in the 1880s by the French ophthalmologist Émile Javal, who used a mirror on one side of a page to observe eye movement in silent reading and found that it involves a succession of discontinuous individual movements. These movements quickly scan objects of attention and aid the brain in grasping a scene visually.