The effect of the shape of the stimulus on spatial summation at the fovea.
D003623:Dark Adaptation; D005403:Fixation, Ocular; D005556:Form Perception; D005584:Fovea Centralis / Q000502:physiology*; D006801:Humans; D008266:Macula Lutea / Q000502:physiology*; D013028:Space Perception