How do observers recognize objects despite dramatic image variations that arise from changes in illumination?
Some evidence suggests that changes in illumi-nation direction influence object recognition (Kersten et al., ARVO 1995). We examine whether illumination dependency extends to face recognition. A corollary issue is whether cast shadows improve performance by providing information about light source direction, or hinder performance by introducing spurious edges that must be discounted prior to recognition. Methods The 3-D geometry and color texture maps of 80 human faces were digitized using a 3-D laser scanner (CyberwareTM). Each face was rendered with the light source located in the upper right or upper left quadrant in front of the face, and with cast shadows present or absent. On each trial, 2 faces were presented sequentially, each followed by a mask (a random array of face features). The two faces were illuminated from either the same or different directions. Observers judged whether the two faces were the same or different individuals. Half of the observers viewed faces with cast
