Filling-in of an Afterimage in Depth Planes

Abstract

Van Lier, Vergeer, and Anstis (2009) demonstrated that an outline contour drawn when viewing an afterimage modulated the afterimage percept. When the contours encompassed only part of the region stimulated by an inducer, the afterimage color at that region was strengthened and was seen to spread homogenously within the contour, even including a region that was not exposed to chromatic stimulation. Here, we investigated variations in the relative depth of the contour and the colored inducing stimulus. As in the previous study, the inducing stimulus was an eight-pointed star with alternating red and green tips and a gray center. The contour consisted of one or two wire-frame lines that formed a four-pointed star. In the one-contour case we observed that the Van Lier afterimage easily transfers across depth planes. Variations in the depth of the wire frame contour did not substantively alter the properties of the afterimage. When two contours were presented simultaneously, but in different depths and with different orientations, the perceived afterimage was stronger (and spread more vigorously to the middle) for the contour perceived to be further away, For the near contour, the tips produce a visible afterimage color but this color did not spread into the interior. The findings demonstrate subtle interactions between boundaries and filling-in mechanisms that depend on relative depth.