Perception by Sensorimotor Coordination in Sensory Substitution for the Blind

Abstract

A contour based technical aid for the blind is presented. This device is intended to enable the perception of object contours and their spatial relations, improving orientation and mobility for the blind. An optical contour sensor reduces environmental information to direction and position of object contours. These relevant contour informations are transmitted to the blind by the cutaneous system at the lower arm as substitution channel. The blind carries the contour sensor like a torch in his hand. He scans an object or a scene by contour tracking and saccades, depending on the context of actual acquired information and his experience knowledge. Recognition results from coordinating the sensory information and the motor reactions in connection with context. Based on schema theory a model of the perception process is proposed. The model is described by a formal grammar generating a symbolic description of the “world” by composing actual sensory informations with motor reactions, including the context of experience by an associator. This model can be extended to a hierarchical structure of concurrent models. Complex perceptual contents are produced stepwise by the elementary informations and reactions. The model is compaired with experimental data. Finally, schema theoretical implications are discussed from an information theoretical point of view.