Temporal and spatial aftereffects of a border on an afterimage and a possible laterality difference

Five subjects were asked to report the brightness and duration of afterimages formed in a region where a border had previously been exposed. The temporal and spatial aftereffects of the border on the formation of the afterimage varied with the duration of the border and these aftereffects were within the area predicted by a photochemical bleaching hypothesis. In addition to these major findings, the experiment yielded some surprising secondary observations. For example, increasing the degree of bleaching or light adaptation made the afterimage brighter if it was on the right side but decreased the brightness if on the left. The difference between afterimages on the right and left sides was discussed in terms of spatial effects of borders and laterality differences.