Abstract
Our field model (Gerbino & Fantoni, 2000; Fantoni & Gerbino, 2001) predicts that the interpolated trajectory between two T-junctions is affected by the size of the retinal gap. Kinetic occlusion displays indicate that interpolation is spatially as well as temporally local. When a diamond with partially occluded vertices undergoes a rigid size transformation, interpolated contours appear increasingly flattened as the retinal gap decreases, making the occluded diamond more and more similar to a disk. Observers estimated the perceived roundness of partially occluded diamonds in kinetic patterns proportionally reduced to a fraction (ranging between 95 and 55 %) of their initial size. Four values of support ratio were used (20, 30, 40, 50%). Data indicate that the perceived roundness of the occluded shape increases as a non-linear function of the amount of reduction. The roundness effect is modulated by the support ratio. As the support ratio decreases, the average roundness effects increases and its rate of convergence to the maximum increases. This trend is adequately explained by a wave function (WF) model described by a differential equation including reduction and support ratio as parameters. The flatness of the wave function depends exponentially on the support ratio. The WF model predicts psychophysical data on static and kinetic completion as well as the perception of curvature of totally specified forms, with 100% support ratio. The WF model provides a general solution to the problem of integrating absolute and relative metric information relevant to shape perception.