Abigail Way¹ (), Ethan Thomas¹, Emma Sutcliffe¹, Timothy Vickery¹; ¹University of Delaware

“Object-based warping” occurs when two reference dots placed within an object are perceived as further apart than equally spaced dots placed on a ground region. Are these distortions due to misperceptions of the locations of the individual dots within the object, or is the illusion due to a misperception of their relative spacing alone? We previously found that expansion effects occur for figure regions compared with ground regions in classic figure-ground frame stimuli with alternating regions, where each region appears as figure or ground due to cues like convexity (Vickery, Sweetman, & Peterson, VSS 2025). Such stimuli offer novel potential to test whether position distortions occur, since all dots appear within the same rectangular frame. In one in-person (N=25) and one preregistered online experiment (N=68), participants viewed visual displays that were divided into alternating black and white regions, with convex or concave curves flanking each region and thus inducing alternating figure/ground percepts. To assess spacing, two reference dots were placed on either figure or ground, and two movable dots were placed in the opposite type of region. To assess position, one reference dot was placed on a figure or a ground region, with one movable dot on the opposite. Subjects matched spacing or position. Replicating earlier results, spacing judgments were larger when reference dots were on figure vs. ground (p < .001). Notably, position was also distorted when the reference dot was placed on a figure vs. ground (p < .001). Congruent with the spacing effects, figure dots were reported as nearer the outside boundary than ground dots. Additionally, spatial and position distortions were correlated (online study: r = .26, p < .05). These findings suggest that distortions in perceived spatial relationships due to figure assignment can at least partially be attributed to misperception of each dot’s position.