Final answer:
The split-brain patient would use their left hand to indicate seeing a mouse because the right hemisphere, which processes the left visual field, controls the left hand. This demonstrates the lateralization of brain functions.
Step-by-step explanation:
The split-brain patient scenario is: B. left hand indicates she saw a mouse. This is because in split-brain patients, the visual information from the left visual field is processed by the right hemisphere, which controls the left hand.
In split-brain patients, the corpus callosum, which connects the two cerebral hemispheres, is severed. As a result, the transfer of information between the hemispheres is disrupted. Visual information received in the left visual field is sent to the right hemisphere of the brain. Similarly, visual stimuli from the right visual field go to the left hemisphere. Because the left hemisphere typically houses the language and speech centers, a split-brain patient can verbally report what is seen in the right visual field. However, they cannot verbally report what is seen in the left visual field since this information is processed in the right hemisphere, which generally lacks the language centers.
In the scenario presented, a split-brain patient would not be able to verbally identify the cat seen in the left visual field. Nonetheless, they can respond non-verbally using their left hand—controlled by the right hemisphere—to indicate recognition of the mouse.