We perceive the world by means of an elaborate set of distinct, modality-specific receptor systems. It is hardly conceivable that losing or lacking a sensory modality would not, in some fashion, alter the capacities of processing, understanding or interacting with the world. Therefore, if lack or loss of a sensory modality leads to a compensatory enhancement of other senses, ultimately resulting in minimal functional loss or even functional gains, these would represent instances of paradoxical functional facilitation. In fact, enhancement of functioning in people with chronic or recent sensory loss has been one of the more widely studied and reliable forms of paradoxical functional facilitation. Individuals with visual loss have been found to show enhanced auditory function, tactile function and even verbal memory performance. Analogously, long-term auditory loss has been associated with enhanced cognitive performance, evident on tactile and visual tasks. Functional brain imaging and transcranial magnetic stimulation studies have pointed to a major reorganization of cerebral function in blind or deaf individuals, and these plastic changes are associated with functional adaptations and gains.
In his novel Blindness, Jose Saramago (1998) uses blindness as a metaphor for both personal misfortune and social catastrophe. A man suddenly loses his vision. Within a few days, people who had contact with him also go blind, and blindness spreads like an epidemic. In the context of practically universal blindness, society breaks down, nothing functions, food and resources become scarce, and lives are threatened. Ultimately, only one character in the novel miraculously avoids blindness.