[Stimulus size and visual illusion of extent]

In psychophysical experiments, the dependence of magnitude of the illusion of extent on the length of the referential part of a modified Brentano figure with different size of the imaginary wings was studied. The experimental data obtained were interpreted in terms of a model based on the concept ofcentroid biases of excitatory patterns, evoked by stimulus terminators. A good resemblance between the expetimental and computational data confirms the modeling assumption on increase of the area of perceptual influence in dependence on the eccentricity in the visual field. The estimated model parameters support a suggestion that distortions of perceived position of the centers-of-masses of stimulus terminators may be considered as one of the main reasons of the illusion of extent. The model parameters also have showed favor to a possible link of the phenomenon of the illusion investigated with perception of three-dimensional coordinates of visual objects.