Control and Functions of Fixational Eye Movements

Abstract

Humans and other species explore a visual scene by making rapid eye movements (saccades) two to three times every second. Although the eyes may appear immobile in the brief intervals between saccades, microscopic (fixational) eye movements are always present, even when an observer is attending to a single point. These movements occur during the very periods in which visual information is acquired and processed, and their functions have long been debated. Recent technical advances in controlling retinal stimulation during normal oculomotor activity have shed new light on the visual contributions of fixational eye movements and the degree to which these movements can be controlled. The emerging body of evidence, reviewed in this article, indicates that fixational eye movements are important components of the strategy by which the visual system processes fine spatial details; they enable both precise positioning of the stimulus on the retina and encoding of spatial information into the joint space–time domain.