Sensory substitution: from sensations to phenomenology.

Sensory substitution refers to the use of one sensory modality (e.g., hearing) to supply environmental information normally gathered by another sense (e.g., vision) while still preserving some of the key functions of the original sense. For example, the use of auditory signals might give information about visual scenes. The development of sensory substitution devices has profoundly changed the classical definition of sensory modalities and contributed to the emergence of a new form of perception. In the last decade, our knowledge about cognitive and brain mechanisms involved in sensory substitution has grown considerably bringing new insights into human perception, neural plasticity. The phenomenological experience of perceiving via a sensory substitution device can now be discussed at the light of the current scientific knowledge. Thanks to technological advances and scientific achievements, sensory substitution has become a real alternative for restoring some functions of a defective sensory organ (e.g., sight in case of blindness or hearing in the case of deafness). This paper addresses some of the major questions raised by sensory substitution, including discussions regarding the nature of perception arising from the use of such devices, demonstrates how the study of sensory substitution enhances our understanding of human perception and brain plasticity and provides an short overview of rehabilitation potentialities.