Is human object recognition better described by geon structural descriptions or by multiple views? Comment on Biederman and Gerhardstein (1993).

Is human object recognition viewpoint dependent or viewpoint invariant under "everyday" conditions? I. Biederman and P.C. Gerhardstein (1993) argued that viewpoint-invariant mechanisms are used almost exclusively. However, our analysis indicates that (a) their conditions for immediate viewpoint invariance lack the generality to characterize a wide range of recognition phenomena, (b) the extensive body of viewpoint-dependent results cannot be dismissed as processing "by-products" or "experimental artifacts," and (c) geon structural descriptions cannot coherently account for category recognition, the domain they are intended to explain. The weight of current evidence supports an exemplar-based multiple-views mechanism as an important component of both exemplar-specific and categorical recognition.