Properties of Familiar Face Representations: Only Contrast Positive Faces Contain All Information Necessary for Efficient Recognition

It is difficult to recognize the identity of a face presented in negative contrast. This difficulty, however, is substantially reduced when only the eye region is contrast positive in an otherwise negative face image, and recognition of these so-called contrast chimeras approaches performance with full positive faces. This apparently similar accuracy has led researchers to suggest that familiar face representations are built around the eye region. The present study used the N250r, an event-related brain potential correlate of repetition priming, to examine whether chimera recognition is similarly efficient as positive face recognition. In a series of 3 experiments, we found a clear N250r for positive but reduced or even absent repetition effects for negative and chimera faces. This finding held true independent of whether the same basic pictures of familiar faces were used as prime and target stimuli (Experiment 1) or not (Experiments 2 and 3). Similar results were also obtained independent of whether positive, negative or chimera primes preceded full positive targets (Experiments 1 and 2) or targets in the same respective contrast format (Experiment 3). These results indicate that only positive faces contain all information necessary for optimal face recognition and that even though contrast chimeras are recognized highly accurately, the underlying processes work less efficiently as compared with normal face recognition. We conclude that familiar face representations are not built around the eyes but comprise detailed information from other regions of the face.