Abstract
The watercolor illusion (WCI) is a color spreading illusion in which an area appears to fill with a pale hue similar to the color of a surrounding inner border. This inner border, or “fringe”, must be surrounded by a contrasting darker border for the illusion to occur. The WCI is a relatively strong cue for figure-ground organization. Rubin’s faces-vase, a reversible figure, can be biased toward faces or vase by including the WCI in that region (Hale, 2019). Other reversible figures have also been tested. Ambiguous figure-ground images consisting of left and right regions can be biased toward figure using the WCI (Hale & McDunn, 2020). In both examples, stimuli consisted of centrally located reversible figures on a dark gray background. All reversible figures fit within a white square divided into regions by a purple line. Orange WCI-inducing fringe was present on one side of the purple border. In all these previous cases, the region containing the WCI was seen as figure more often. The current experiment sought to examine the role of surface luminance on the WCI as a figure cue. Having a luminance difference between the regions should make each region more physically distinct in terms of figure-ground organization. The same ambiguous figures from Hale & McDunn (2020) were used; however now they consisted of a white and light gray region instead of two white regions. Results indicate the effect of the WCI was impacted by this change. When collapsing across white and gray, the WCI appears to have no impact on figure-ground. However, participants reported the gray WCI-containing region as figure more often than the white WCI-containing region. This may be due to an interaction between the WCI-containing region and its contrast with surrounding regions. This is the first study to explore the interaction between these factors.