The perceived size of targets in the peripheral and central visual fields.

Previously described misperceptions of target size in the peripheral visual field have been conflicting. We found that whether an illuminated peripheral target appears larger or smaller than a foveal target of the same physical size depends upon luminance: in general, dim peripheral targets are underestimated and bright peripheral targets are overestimated in size. We attribute misestimations of peripheral target size primarily to the optical degradation of peripheral retinal images and propose a qualitative model for how image extent may be determined by the visual system.