Angular Disinhibition Effect in a Modified Poggendorff Illusion

Visual illusion can be strengthened or weakened with the addition of extra visual elements. For example, in Poggendorff illusion, with an additional bar added, the illusory skew in the perceived angle can be enlarged or reduced. In this paper, we show that a nontrivial interaction between lateral inhibitory processes in the early visual system (i.e., disinhibition) can explain such enhancement or degradation of the illusory percept. The computational model we derived successfully predicted the perceived angle in a modified Poggendorff illusion task with an extra thick bar. The concept of disinhibition employed in the model is general enough that we expect it can be further extended to account for other classes of geometric illusions.