A saccade is a short, rapid type of eye movement. 1000 degrees per second is the largest velocity saccades can reach. This type of movement happens when a person or animal switches a gaze between several objects rapidly. Due to the speed of a saccade, an observer of such eye movements may not be able to perceive the subtle "jumping" movement of a saccade.
This type of movement has been studied in humans. However, this movement is present in other animals. Examples are vertebrates without a fovea, insects, and even some birds.
Interestingly, saccadic eye movements are affected by changes in dopamine and emotion. An article from the National Institutes of Health called "Subtle Saccades," featuring researchers Okihide Hikosaka and Simon Hong, states the following:
"'Our animal subjects move their eyes slower when they are disappointed,
as opposed to the energized, ballistic movements they make when they are
motivated,' Hong says. 'We found that the emotional circuit interacts
with the motor circuit to make it move faster or slower.'"
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