Grating summation in fovea and periphery.
D005403:Fixation, Ocular; D005584:Fovea Centralis / Q000502:physiology; D006801:Humans; D008297:Male; D008959:Models, Neurological; D012160:Retina / Q000502:physiology*; D013028:Space Perception / Q000502:physiology*; D014792:Visual Acuity; D014794:Visual Fields