DODGE, who was the first systematically to study and classify the various types of eye movements, attached the name "saccadic movement" to the rapid changes in position of the eyeball which are typically found between fixational pauses during reading. He also observed that the movements constituting the fast phase of opticokinetic and vestibular nystagmus have similar characteristics. Most experimenters have found that all voluntary movements executed in the absence of a moving visual stimulus are saccadic, and even "pursuit" movement patterns, in response to moving visual stimuli, can be demonstrated to contain saccadic components. This widespread occurrence of saccadic movements in the normal human and the fact that they can be observed in very young infants and in lower species with good ocular motility suggest that they constitute a basic response pattern in the oculomotor system.
The mechanism by which the changes in eye position characteristic of saccadic movements are