The neural basis for shape preferences

Several dimensions of shape, such as curvature or taper, can be regarded as extending from a singular (S) or 0 value (e.g., a straight contour with 0 curvature or parallel contours with a 0 angle of convergence) to an infinity of non-singular (NS) values (e.g., curves and non-parallel contours). As orientation in depth is varied, an S value remains S, and a NS value will vary but will remain NS. Infant and adult human participants viewed pairs of geons where one member had an S and the other had a NS value on a given shape dimension, e.g., a cylinder vs. a cone. Both adults and infants looked first, and adults looked longer at the NS geons. The NS geons also produced greater fMRI activation in shape selective cortex (LOC), a result consistent with the greater single unit activity in macaque IT produced by those geons (Kayaert et al., 2005). That NS stimuli elicit higher neural activity and attract eye movements may account for search asymmetries in that these stimuli pop out from their S distractors but not the reverse. A positive association between greater activation in higher-level areas of the ventral pathway and visual preference has been demonstrated previously for real world scenes (Yue, Vessel, & Biederman, 2007) and may reflect the workings of a motivational system that leads humans to seek novel but richly interpretable information.