Extension of a computational model of a class of orientation illusions

Polarity-dependent orientation illusions constitute a class of illusions in which the impression of orientation does not depend only on geometrical relations between its elements, but also on the relations between their luminances. Several examples of such figures are presented in the paper. Todorović (2021a) presented a simple computational model of such phenomena. Simulations of the model indicated that a common feature of the neural basis of these illusions is the presence of certain neural structures called ‘oblique clusters’. A limitation of the model was that it used a restricted set of parameters. In this paper a generalization of the model is introduced involving types of receptive fields, their orientation sensitivity and their size or spatial frequency tuning. The simulations of the new model indicated that oblique clusters were present in the reaction patterns under a much wider set of conditions, though not all. The original hypothesis that oblique clusters constituted the neural foundations of impressions of tilt in this class of illusions was vindicated.