Separate influences of orientation and lighting in the inverted-face effect.

Studies of the inverted-face effect typically use photos as stimuli. Inverting photos not only misorients the face but also reverses important shading and shadow cues. We decoupled the influence of spatial orientation and the direction of lighting in three experiments and found that the relation between these factors varied with the task given to observers. When the task required identification of faces (Experiments 1 and 3), the factors were additive, consistent with a strategy of mental rotation of the face prior to an interpretation of the shading cues. When faces were assigned to coarse categories (Experiments 2 and 3), these factors interacted, consistent with a more piecemeal approach to face processing. We propose that the identification of a specific individual depends on configurational information, which is preserved if the image of an inverted face is mentally rotated before the identification process is begun.