Abstract
Gestalt psychologists emphasized the importance of figure-ground assignment in the process of perceptual organization. A border separating two regions “belongs” to the region perceived as figure. This region is seen as an occluder covering the ground region. In some configurations, such as Rubin’s (1929) faces-vase, figure-ground assignment is ambiguous and can be reversed. Previous research has demonstrated color spreading illusions can bias figure-ground reversibility in ambiguous stimuli such as the faces-vase (Hale, 2018) and in stimuli with no semantic content (Hale & McDunn, 2019). In the current study, we manipulated relative surface area and luminance to determine if these factors impact figure-ground organization under certain stimulus conditions. Stimuli were centrally located squares on a dark background. Each stimulus consisted of a light gray region and white region separated by one of six wavy contours, resulting in left and right regions. Participants viewed these images on a screen and reported whether the left or right region of each stimulus appeared to be the foreground. The wavy contour was either centrally located, shifted left, or shifted right, resulting in a perceived size change between stimuli (i.e., matched size, larger right, or larger left). Light gray and white alternated between left and right. Trials were presented in a random order in this within-subjects design. All six wavy contours, when centrally located, were statistically reversible implying no figural bias for left versus right. A 2 (Luminance) x 2 (Surface Area) repeated-measures factorial ANOVA found no main effect of luminance and no interaction between luminance and surface area. However, a main effect of surface area was found, suggesting larger regions were biased toward figure and smaller regions biased toward ground. Based on these findings, we plan to re-introduce color spreading illusions to investigate the interaction of these factors on figure-ground organization.