The Rich Afterimage Illusions under Head-Image Tilting and the Internal Visual Space Model. A New Theoretical Comprehending

Some features of the illusions arising from the movement of the observer’s eyes and/or head under the background of the positive afterimage of the entire visual scene (rich afterimage-rAI) when the head and/or afterimage are tilted are described.

Under these conditions, there are the violations of the visual direction constancy and stability of not only the visual field but also near extrapersonal space. This happens also under the constant position of the eyes in orbits when changing of the fixation point by the head movements. The illusion of violation of the visual vertical on the background of an inclined rAI is also described. It turns out that the synthesis of the field of rAI does not depend on the state of eye vergence in a wide range.

The features of the so-called “residual illusion” are described in detail. In this phase all phenomena that have arisen against the background of rAI persist for tens of seconds in total darkness after the rAI is completely attenuated. This also applies to distorted perception of the visual vertical.

Based on the analysis of the rAI illusions and peculiar properties of the rich afterimage itself, it is proposed to consider the hypothesis, suggesting the complete nonparticipation of the efferent oculomotor subsystem signals in the mechanisms of the visual field constancy and the gaze direction constancy. The hypothesis suggests that the structurally rich visual scene allows the visual system to form a stable visual field and to calculate the observer’s gaze direction only based on the signals within the visual flow. The hypothesis allows to coherently interpret the main phenomena have been observed in the experiments. And the observation of an oblique 3-D rAI when the head is tilted to the shoulder clearly indicates that not the images on the retinas, but the internal visual space (IVS) model is the object of vision.