Dungeons, gratings, and black rooms: A defense of double-anchoring theory and a reply to Howe et al. (2007)

The double-anchoring theory of lightness (P. Bressan, 2006b) assumes that any given region belongs to a set of frameworks, created by Gestalt grouping principles, and receives a provisional lightness within each of them; the region’s final lightness is a weighted average of all these values. In their critique, P. D. L. Howe, H. Sagreiya, D. L. Curtis, C. Zheng, and M. S. Livingstone (2007) (a) show that the target’s lightness in the dungeon illusion (P. Bressan, 2001) and in White’s effect is not primarily determined by the region with which the target is perceived to group and (b) claim that this is a challenge to the theory. The author argues that Howe et al. misinterpret grouping for lightness by equating it with grouping for object formation and by ignoring that lightness is determined by frameworks’ weights and not by what appears to group with what. The author shows that Howe et al.’s empirical findings, together with those on grating induction and all-black rooms that they cite as problematic, actually corroborate, rather than falsify, the double-anchoring theory.