Fig. 4.

Hypothetical relation between distinctiveness and symmetry perception. Part summation causes symmetric objects to become more distinctive in the underlying neural representation (a) compared with asymmetric objects. If this property drives symmetry perception, symmetry judgments should be determined at least in part by a decision boundary that separates symmetric and asymmetric objects on the basis of their distinctiveness. If distinctiveness is the underlying quantity driving symmetry detection, then objects close to the decision boundary should be the hardest to judge during symmetry detection (b), whereas objects far away from the boundary should be easy. Specifically, this hypothesis predicts that symmetry detection time should decrease as symmetric objects become more distinct but should increase as asymmetric objects become more distinct. Note that this is qualitatively different from the pattern expected from salience: Salient objects would produce faster responses for both symmetric and asymmetric objects.