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Abstract:
Purpose: The aim of this study was to produce facial caricatures of 3D laser scans of human heads, using algorithms that exaggerate the distinctive information in faces. These algorithms operate by comparing a face's "feature" dimensions to those of an average face, and by exaggerating the feature dimensions that are unusual for the face. When applied to the 2D configural features in faces (e.g., distance between eyes, nose length, etc.), this algorithm produces more distinctive versions of the faces. Methods: We applied this algorithm to 60 pointwise-corresponded 3D heads and found, to our surprise, that the most salient effect of the algorithm was to increase the apparent age of the face. Empirically, 10 human observers estimated the ages of the veridical faces, two levels of caricature, and one level of anti-caricature, and we measured the error of these estimates. Results: We found a highly reliable effect of caricature level on age estimate error, with errors ordered from youngest to oldest for all 10 observers as follows: anti-caricatures, veridicals, level one, and level two caricatures. Face age in this last case was overestimated by an average of 20 years. Discussion: Exaggerating the distinctive 3D information in a face increased the apparent age of the face, both at a local level by exaggerating small facial creases into wrinkles, and at a more global level via changes that made the underlying structure of the skull more evident.
