In split-brain syndrome, a patient may fail to name an object seen in the left hand but can perform a matching task with the right hand. This phenomenon is best described as?

• A. Hemispheric disconnection
• B. Aprosody
• C. Split-brain syndrome
• D. Anterior cerebral artery syndrome

Answer: (C)

The key idea is interhemispheric disconnection. When the corpus callosum is severed, the two hemispheres can’t share information, so each side of the brain operates more or less independently. Language is typically localized to the left hemisphere, which handles naming, while the right hemisphere handles many nonverbal and spatial tasks. If an object is processed by the right hemisphere (for example, seen or felt on the left side), it can be recognized but not verbally labeled because that recognition can’t cross to the left-hemisphere language centers. Yet the right hemisphere can still guide nonverbal actions, such as a matching task, even though it cannot transfer the verbal label to the left hemisphere. This dissociation—unable to name something perceived by the right hemisphere but able to perform a nonverbal task with the opposite hand—is the classic pattern of split-brain syndrome, caused by hemispheric disconnection.