Any asymmetry in the function of the nervous system, particularly a functional specialization between left and right cerebral hemispheres of the brain in vertebrates (see cerebrum). Such asymmetries occur in a wide range of animals, from invertebrates to humans. For example, studies in humans have shown that language ability resides in the left cerebral hemisphere in around 90% of individuals, while visuospatial processing (e.g. recognition of faces, patterns, and spatial relations) resides more often in the right hemisphere. However, variations in this are common; for example, around a quarter of left-handed people have right-hemisphere language areas, and in some individuals language functions are divided between the hemispheres.