AP Psychology Practice Test

What is the result of cutting the connecting fibers in a split-brain patient?

1. Enhancement of sensory functions

2. Isolation of the two brain hemispheres

3. Improvement in hormone production

4. Increased plasticity

The correct answer is: Isolation of the two brain hemispheres

The result of cutting the connecting fibers in a split-brain patient is indeed the isolation of the two brain hemispheres. This surgical procedure, often performed to alleviate severe epilepsy, severing the corpus callosum, which connects the left and right hemispheres of the brain, leads to each hemisphere operating independently. In this state, the two hemispheres cannot communicate as they normally would, resulting in unique behaviors and cognitive functions that can be observed. For instance, if an image is presented to the right visual field, it can be processed by the left hemisphere, allowing the patient to verbalize what they see. However, if the image is presented to the left visual field, it is processed by the right hemisphere, which usually cannot communicate the information verbally to the left hemisphere. This phenomenon highlights the distinct capabilities and limitations of each hemisphere when they are not integrated, illustrating how the brain’s structure directly influences behavior and cognition.