Visual information can be provided to blind users through sensory substitution devices that convert images into sound. Through extensive use to develop expertise, some blind users have reported visual experiences when using such a device. These blind expert users have also reported visual phenomenology to other sounds even when not using the device. The blind users acquired synthetic synaesthesia, with visual experience evoked by sounds only after gaining such expertise. Sensorimotor learning may facilitate and perhaps even be required to develop (...) expertise in the use of multimodal information. Furthermore, other areas where expertise is acquired in dividing attention amongst cross-modal information or integrating such information might also give rise to synthetic synaesthesia. (shrink)

If a man born blind were to gain his sight in later life would he be able to identify the objects he saw around him? Would he recognise a cube and a globe on the basis of his earlier tactile experiences alone? This was William Molyneux's famous question to John Locke and it was much discussed by English and French empiricists in the eighteenth century as part of the controversy over innatism and abstract ideas. Dr Morgan examines the whole history (...) of this debate: Locke's own (negative) answer to the question, the contributions of Berkeley, Condillac, Diderot and Voltaire and the factual accounts of early cataract operations and modern laboratory studies. He shows how this debate is involved in the development and eventual separation of philosophy and experimental psychology after the eighteenth century and considers why the original question is effectively still unanswered. This is one problem-area with its intricate cluster of connected conceptual and technical difficulties which suggests the need for some reunion or at least collaboration between the two subjects. (shrink)

In this paper we wish to bring together two seemingly independent areas of research: synaesthesia and sensory substitution. Synaesthesia refers to a rare condition where a sensory stimulus elicits not only the sensation that stimulus evokes in its own modality, but an additional one; a synaesthete may thus hear the word “Monday”, and, in addition to hearing it, have a concurrent visual experience of a red color. Sensory substitution, in contrast, attempts to substitute a sensory modality that a person has (...) lost by transforming the information it provided so that it can be accessed through another, intact sensory modality. To make visual information accessible to a blind person, for example, data taken by a camera would be transformed into tactile or auditory information. What do synaesthesia and sensory substitution have in common? Research in both of these areas contributes to our understanding both of cross-modal cooperation and of sensory sensations or qualia, asking under what circumstances these can arise in a modality that is not stimulated. Synaesthesia reveals that this “sensory cross-activation” is possible, and sensory substitution research hopes to induce it. In this article, we will review briefly the literature on synaesthesia, and discuss the issue of qualia for this domain of research. We will then address the evidence for synaesthesia and visual qualia in the blind, and the research on sensory substitution, to finally ask whether sensory substitution may induce a ‘synthetic’ form of synaesthesia by taking advantage of the nervous system’s capacity for generating visual images in the absence of retinal input. (shrink)