Abstract
Gelb, (1929) and Land & McCann, (1971) observed that a spot-in-a-void (SIV), a single illuminated surface in a dark room, will appear white or luminous regardless of its luminance level. These researchers and others have reported that a (SIV) perceptually darkens when a second brighter surface is placed spatially adjacent to it. The darkening can best be explained by a process of spatial anchoring. Spatial anchoring (Gilchrist et al, 1999) considers a range of physical luminances as a floating range that is anchored to a perceptual lightness scale based on the rule that the surface with the highest luminance in a spatial framework is perceived as white and other luminances are scaled accordingly. The current investigators have found that a SIV is not always perceived as white, and is influenced by not-retinal temporal relationships. For example if a bright SIV is presented to observers for 10 sec and then within a 32 sec ISI a dim SIV is presented, the dim SIV appears middle gray. This can best be understood in terms the concept of temporal anchoring, or anchoring over time. The importance of articulation in a spatial scene has been clearly demonstrated by others. Current results showing that; 1) a spatially articulated area darkens a subsequent SIV to a greater degree than a non-spatially articulated SIV; 2) an articulated temporal framework (increasing the number of SIVs over time) also has a greater darkening on a subsequent SIV, and; 3) temporal anchoring abides by the same rules as spatial anchoring will be presented.