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Face Perception

Work in colloboration with Alice O´Toole.


Three-dimensional Caricatures : An algorithm for aging faces?
We applied a standard facial caricaturing algorithm to a three-dimensional representation of human heads. This algorithm sometimes produced heads that appeared ``caricatured''. More commonly, however, exaggerating the distinctive three-dimensional information in a face seemed to produce an increase in 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 seemed to make the underlying structure of the skull more evident. Concomitantly, de-emphasis of the distinctive three-dimensional information in a face made it appear relatively younger than the veridical and caricatured faces. More formally, face age judgements made by human observers were ordered according to the level of caricature, with anti-caricatures judged younger than veridical faces, and veridical faces judged younger than caricatured faces. We discuss these results in terms of the importance of the nature of the features made more distinct by a caricaturing algorithm and the nature of human representation(s) of faces.

Original Laser Scan 27 yr old male

Charicatures - increased distance from mean

Three-dimensional caricatures of human heads: Distinctiveness and the perception of facial age.

A.J. O'Toole, T. Vetter, H. Volz and E.M. Salter, Perception, 26 (1997) 719-732.

    The sex of a face is perhaps its most salient feature.
The average head plus versus minus the first eigenvector for the head surface data is shown. The analysis was performed on 65 female and 65 male heads. Individual face projections onto this eigenvector were highly correlated to the gender of the face.

A principal components analysis (PCA) was applied separately to the three-dimensional structure and texture data from laser-scanned human heads. Individual components from both analyses captured information related to the sex of the face. Notably, single projection coefficients characterized complex structural differences between three-dimensional male and female heads and between male and female texture maps. In a series of simulations, we compared the quality of the information available in the head versus texture data for predicting in the sex of the face. The results indicated that the three-dimensional structural data supported more accurate sex classification than the texture data, across a range of PCA-compressed (dimensionality-reduced) representations of the heads. This kind of dual face representation can give insight into the nature of the information available to humans for categorizing and remembering faces.

Sex classification is better with three-dimensional head structure than with texture.
A.J. O'Toole, T. Vetter, N.F. Toje and H.H. Bülthoff, H. H. Perception, 26:75-84.