Abstract
A striking phenomenon in face perception is the configural effect in which a difference in a single part appears more distinct in the context of a face than it does by itself (Tanaka & Farah, 1992, Fig. 1). Because the face context is identical it would be expected to increase search complexity, rendering recognition/discrimination morenot lessdifficult. Remarkably, there has never been a biologically plausible explanation of this fundamental signature of face recognition. We show that the configural effect can be simply derived from a model composed of overlapping receptive fields (rfs) characteristic of early cortical simple-cell tuning but also present, possibly without the linking of spatial frequency (SF) to rf size, in face-selective areas. Because of the overlap in rfs, the difference in a single part (between target and foil) is not only represented in the rfs centered on it, but also propagated to larger rfs centered on distant parts of the face. Similarity values computed from the model between pairs of faces and pairs of face parts closely matched the recognition accuracy of human observers who had learned a set of faces composed of composite parts and were tested on wholes (Which is Larry?) and parts (Which is Larrys nose?). That it is the larger rfs rather than low SFs that account for the configural effect was documented in an experiment in which the stimuli were high vs. low passed (Fig. 2). The configural effect was found to be largely insensitive to SF. The retention of a configural (rather than a part) representation may be unique to the representation of faces and explains why distinguishing similar faces (unlike distinguishing objects of equivalent physical similarity) is ineffable (because we do not have cognitive access to the rf activation values) and so adversely affected by inversion and contrast reversal.
Meeting abstract presented at VSS 2014