When only the right hemisphere is left: studies in language and communication.

An adult of above normal intelligence, BL, underwent left hemispherectomy at age five, and subsequently graduated from college and has been regularly employed. Using standardized neuropsychological instruments, previous extensive testing had revealed optimal performance for a hemispherectomized subject. To probe communicative abilities in greater detail, and to examine current questions about linguistic superiority of the left hemisphere and "crowding" of right hemisphere functions, 12 additional protocols were administered. BL performed at normal or above on nearly all protocols. However, performance on production of phonemically complex words was effortful, and deficits were seen on two tests requiring comprehension of linguistic contrasts in prosody (Linguistic Prosody Test) and syntax (the Active-Passive Test). These findings support previous claims of reduced ability in specific, circumscribed linguistic functions in the left hemispherectomized person, and lead to suggestions for further testing of communicative competence in individuals with a single intact hemisphere.