Eye Movements during Fixation

As you read this, your eyes are rapidly flicking from left to right in small hops, bringing each word sequentially into focus. When you stare at an object, your eyes will similarly dart here and there, resting momentarily at one place on the object, and then moving to another. But these large eye movements, called saccades (see color insert, Figure 25a), turn out to be just a small part of the daily workout your eye muscles are getting. Your eyes never stop moving, even when they are apparently settled, say, on a person's nose or a sailboat bobbing on the horizon. When the eyes fixate on something, as they do for 80% of your waking hours, they still jump and jiggle imperceptibly in ways that ...