Levels of Processing in Matching Photos of Unfamiliar Faces

The ability to indicate whether two face-images belong to the same person or to two different identities is a crucial skill in many practical settings such as: passport control, surveillance, and eye-witnessing. However, despite extensive research, the mechanisms that govern face-matching are still not understood. This is partly due to limitations of the original face-matching paradigm. The present study develops a modified face-matching task that overcome these constraints. The paradigm is modeled after the classic same-different paradigm, and as such affords a tighter experimental control and a more rigorous theoretical resolution of the face-matching process: (a) the task is speeded, (b) a physical condition is added where two identical face-images are presented side-by-side, and (c) the level to which participants draw their attention (physical, nominal) is manipulated across blocks. The results with upright faces (Experiment 1) support a hierarchical model of processing, according to which featural, physical and nominal levels are processed in a serial self-terminating fashion. The results with inverted faces (Experiment 2) are less supportive of such a mechanism. Implications for central debates in the face-recognition field such as image-variability, face-space, and inversion are discussed.