title: Positive and negative afterimages from brief target gratings.
abstract: Threshold luminance levels for the production of negative afterimages from brief target gratings were determined as a function of background luminance and grating frequency. The obtained thresholds were extremely low--typically below the values that would maintain constant space-average luminance between target and background. The implications of these results for other studies that may have inadvertently produced negative afterimages with their stimulus conditions were noted. As a demonstration, visual persistence estimates from these gratings were determined under conditions that carefully excluded negative afterimages, and clear differences from previously published work were obtained.
mesh_terms: D000360:Afterimage / Q000502:physiology*; D005556:Form Perception / Q000502:physiology*; D006801:Humans; D008027:Light; D010364:Pattern Recognition, Visual / Q000502:physiology*; D012684:Sensory Thresholds / Q000502:physiology; D013997:Time Factors