THE EFFECTS OF TWO TYPES OF COORDINATE SYSTEMS ON LOCALIZATION OF PERIPHERAL LIGHT FLASHES

Abstract : Ten groups of subjects localized single flashes, viewing monocularly, and responding with a projection pointer. Flash sources were located within a 64-degree circular field in a blacked out room. One group saw only a fixation point. For another group only a cross was projected. Four groups were shown Cartesian coordinates, and four groups were shown polar coordinates. The density of the coordinate lines for the respective groups was increased by successive rectangular or polar bisection of the coordinate units, beginning with the cross. There were no appreciable differences in localization error between the groups which used one type of co ordinate system and those which used the other. Introduction of the coordinate cross, and the bisection of the cross, led to successively smaller errors in localization, but futher in creases in line density did not. All groups made constant errors of localizing flashes closer to the visual axis than they actually were.