The vocabulary of shape: principal shapes for probing perception and neural response.

Humans perceive shape rapidly and effortlessly but have great difficulties describing what they perceive. This suggests that the representation of shape in the brain is abstract and very unlike that used in conscious thought. Here we explore the proposal that this representation is matched to the statistical properties of objects in the environment. From an ensemble of several hundred laser-scanned three-dimensional (3D) human heads we extract the principal components which provide a compact basis for head shape. We show that, with good accuracy, a given head can be represented by linear combinations of a few dozen primary shapes just as colours can be synthesized by combining the three principal colours. We suggest new perceptual adaptation experiments for testing the brain's shape representation system. The principal head shapes can also be used to probe response properties of 'face-cells' in the inferior temporal cortex.

[1]  M. Webster,et al.  The influence of contrast adaptation on color appearance , 1994, Vision Research.

[2]  D. Marr.  A theory for cerebral neocortex , 1970, Proceedings of the Royal Society of London. Series B. Biological Sciences.

[3]  J. Atick,et al.  Temporal decorrelation: a theory of lagged and nonlagged responses in the lateral geniculate nucleus , 1995 .

[4]  J. Atick,et al.  STATISTICS OF NATURAL TIME-VARYING IMAGES , 1995 .

[5]  Joseph J. Atick,et al.  Towards a Theory of Early Visual Processing , 1990, Neural Computation.

[6]  C. Gross,et al.  Representation of visual stimuli in inferior temporal cortex. , 1992, Philosophical transactions of the Royal Society of London. Series B, Biological sciences.

[7]  Terrence J. Sejnowski,et al.  Network model of shape-from-shading: neural function arises from both receptive and projective fields , 1988, Nature.

[8]  E T Rolls,et al.  Neurophysiological mechanisms underlying face processing within and beyond the temporal cortical visual areas. , 1992, Philosophical transactions of the Royal Society of London. Series B, Biological sciences.

[9]  Joseph J. Atick,et al.  What Does the Retina Know about Natural Scenes? , 1992, Neural Computation.

[10]  J AtickJoseph,et al.  Statistical approach to shape from shading , 1996 .

[11]  Berthold K. P. Horn,et al.  Shape from shading , 1989 .

[12]  J. Atick,et al.  Statistical Approach to Shape from Shading : Reconstruction of 3 D Face Surfaces from Single 2 D , 1997 .

[13]  William Bialek,et al.  Statistics of Natural Images: Scaling in the Woods , 1993, NIPS.

[14]  R. Desimone.  Face-Selective Cells in the Temporal Cortex of Monkeys , 1991, Journal of Cognitive Neuroscience.

[15]  L Sirovich,et al.  Low-dimensional procedure for the characterization of human faces. , 1987, Journal of the Optical Society of America. A, Optics and image science.