In psychophysics, it has been found that some types of VPL depend on perceptual constancy that corresponds to stable representation of certain properties of an object despite variable visual input. Such representation is thought to occur in the mid visual stage (Garrigan& Kellman 2008). Although training on a task of discriminating close motion directions or orientations leads to VPL specific to the trained direction (Ball & Sekuler 1987) or orientation (Ahissar & Hochstein 1993), learning by training in discriminating larger direction or orientation differences transfers to untrained directions