APA Dictionary of Psychology

the extent of visual space over which vision is possible with the eyes held in a fixed position. In humans, the outer limit of vision for each eye extends approximately 60° nasally, 90° temporally, 50° superiorly, and 70° inferiorly. The extent varies with age: Very young children and older people have a smaller visual field. Objects nearest to the fixation point are seen with greatest clarity because visual acuity, spatial contrast sensitivity, and color vision are best in the foveal region.