Principles governing the effects of sensory loss on human abilities: An integrative review

Blindness or deafness can significantly influence sensory abilities in intact modalities, affecting communication, orientation and navigation. Explanations for why certain abilities are enhanced and others degraded include: crossmodal cortical reorganization enhances abilities by providing additional neural processing resources; and sensory processing is impaired for tasks where calibration from the normally intact sense is required for good performance. However, these explanations are often specific to tasks or modalities, not accounting for why task-dependent enhancement or degradation are observed. This paper investigates whether sensory systems operate according to a theoretical framework comprising seven general principles (the perceptual restructuring hypothesis) spanning the various modalities. These principles predict whether an ability will be enhanced or degraded following sensory loss. Evidence from a wide range of studies is discussed, to assess the validity of the principles across different combinations of impaired sensory modalities (deafness or blindness) and intact modalities (vision, audition, touch, olfaction). It is concluded that sensory systems do operate broadly according to the principles of the framework, but with some exceptions.