A “saccade” is a rapid movement of the eyeball between two fixed focal points. During this brief moment, the brain hides this blurry motion from our perception. Once a saccade motion has begun, the destination cannot change, meaning that if the target of focus disappears the viewer won’t know until the saccade completes. If the field of vision is changing too quickly, the saccades may never be able to arrive at and focus on a target, instead, the objects in view are only perceived through peripheral vision.