ABSTRACT
This chapter explores the importance of visual experience for cognitive processes, with particular focus on their perception of the environment and subsequently how blind individuals “see” the world in the context of research in psychology and neuroscience. The current state of the art will examine a number of crucial areas of research, including: evidence for compensatory plasticity, whereby the remaining senses develop supranormally to overcome the missing sense; the extent to which there is evidence for the general-loss hypothesis that missing one sense has detrimental effects on the other senses; the impact of lower-level perceptual changes arising from sensory loss on higher-level cognitive processing; and the role of critical or sensitive periods in brain development and the age of onset for sensory impairment. These areas of research are then applied to our understanding of the structure and function of the brain, with accumulating evidence for the metamodal hypothesis that the brain is organised by task or computation, and not by the primary senses, and that this occurs on the basis of existing multisensory networks throughout the brain. This research has implications for long-standing philosophical questions about the nature of perception and for developing assistive technology for the visually impaired, such as sensory substitution devices.
