From: The World In Your Head by Steven Lehar

Fig. 8.7 Reification through rotation invariance. (A) With a weak top-down priming of a “+” feature, the reification is indeterminate, as the pattern attempts to reify itself at all orientations simultaneously. (B) With a stronger prime the pattern is reified at some arbitrary orientation, but remains free to spin like a compass needle. (C) A touch on the plate with a finger breaks the symmetry and locks the reified pattern to an orientation that matches the damped input. (D) A noisy pattern is reified and completed at the orientation that best matches the primed pattern. (E) One possible series of three-dimensional standing-wave patterns that extend the representation of the occlusion, coplanarity, and orthogonality fields described in chapter 4 with higher order patterns of symmetry at planar intersections.