Multiple mechanisms of illusory contour perception.

A variety of mechanisms have been proposed to explain illusory contour formation. However, since prior studies have focused on a single mechanism, there is no clear consensus regarding contour formation mechanisms. Here we developed a novel vivid dynamic display we call the chomping pacman that allows measurement of minute differences in contour clarity. This illusion is shown to be more vivid than traditional static displays. Using the method of adjustment, we are able to identify three mechanisms of contour formation: extrapolation, interpolation, and figural. We posit that these three mechanisms combine to form the general illusory contour percept in traditional static Kanizsa displays and likely contribute to real-world contour perception.