ABSTRACT
This chapter discusses perceptual and spatial disorders, in relation to the selective impairment of specific aspects of perceptual and spatial systems. It also discusses syndromes, within which perceptual and spatial disorders are cardinal features. Perceptual and spatial disorders in children have been much less extensively investigated than language disorders. Standard clinical taxonomies such as Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) do not recognise perceptual or spatial disorders as self-contained and specific impairments in the way that language disorders are identified, as are reading, writing, arithmetical, and motor disorders. The possible restrictions in the degree of spatial skill which follow congenital blindness therefore either relate to the sustained absence of visual information or the severe reduction of visual input during a critical period. Transient ictal blindness refers to the loss of visual sensation, with sudden onset, associated with an epileptic fit. In visual hallucinations, there is subjective awareness of a stimulus that is not present.
