White's effect: removing the junctions but preserving the strength of the illusion
Margaret S. Livingstone, Piers D. L. Howe · Journal of Vision · 2010
White's effect (also known as the Munker-White effect) is a lightness illusion in which, contrary to expectations based on simultaneous contrast and Wallach's rule, a gray rectangle predominantly surrounded by white appears lighter than an identical gray rectangle that is mainly surrounded by black. The illusion is often explained in terms of T-junctions that are formed by the three-way intersection of the gray rectangle, a black stripe and a white stripe. In our study we employed a circular variant of White's effect in which all the junctions had been removed. We found that the strength of the illusion was not significantly affected, suggesting that junctions are not an important consideration in all versions of White's effect. We argue that we can explain this new illusion, as well as certain other challenging versions of White's effect, in terms of Gestalt grouping laws and the Anchoring Theory of Lightness Perception (Gilchrist et al., 1999, Psychological Review, 106 795–834).