The Perception of a Visual Object During Stimulation of the Vestibular System

Abstract

The localisation of a visual object in space is not only determined by the image on the retina but also by extra-retinal factors. Several of these factors concern the interpretation of observed phenomena. However the labyrinth too contributes to the perception of the visual sphere. Examples are given of oculogravic and opto-gyral illusions elicited respectively by stimulation of the otoliths and of the semicircular canals. As contrasted with the general accepted explanation, arguments can be advanced which show that the opto-gyral illusions are independent of nystagmus. According to the author, both kinds of illusions arc considered as a tendency to correlate optical, haptic and vestibular cues as an expression of a cerebral correlative function. In the absence of optical orientational cues containing a factor of experience, which is also the fact with a mere lightpoint in the dark, the vestibular impression will be dominant. Within certain limits the adaptation of the optical impression to the vestibular information is perfect. In stronger stimulation of the vestibular apparatus dissociation appears. Highly non-physiological stimulation gives an complete absence of correlation which results in a disorientation penetrating into the consciousness.