Are face representations viewpoint dependent? A stereo advantage for generalizing across different views of faces.

Almost all previous studies of face recognition have found that matching the same face depicted from different viewpoints incurs both reaction time and accuracy costs. This has been interpreted as evidence that the underlying neural representations of faces are viewpoint-specific, but such a conclusion depends on the experimental data being an accurate reflection of real-world viewpoint generalisation. An equally plausible explanation for poor viewpoint generalisation in experimental situations is that important information that is normally used to generalize across views in real-world settings is not available in the experiment. Stereoscopic information about the three-dimensional structure of the face is systematically misleading in nearly all previous investigations of face recognition, since a face depicted on a computer monitor contains explicit stereoscopic information that the face is flat. The current experiment demonstrates that viewpoint costs are reduced by depicting the face with stereoscopic three-dimensionality (compared to a synoptically presented face), raising the possibility that the viewpoint costs found in face recognition experiments might be a better reflection of the information that is typically unavailable in the experimental stimuli than of the underlying neural representation of facial identity.