Several dimensions of shape, such as curvature or taper, can be regarded as extending from a singular or zero value (e.g., a straight contour with 0 curvature or parallel contours with a 0 angle of convergence) to an infinity of non-singular values (e.g., curves and non parallel contours). As orientation in depth is varied, a singular value remains singular, and a non-singular value will vary but remains non-singular. Infant and adult human participants viewed pairs of geons where one member had a singular and the other had a non singular value on a given shape dimension, e.g., a cylinder vs. a cone. The participants preferred to look at the nonsingular geons. Such geons also produced greater fMRI activation in shape selective cortex (LOC), as well as greater single unit activity in macaque IT. The preference for non-singular shapes may derive from their elicitation of greater cortical opioid activity (Biederman & Vessel, 2006).