Scientists have known for centuries that we "speak" with the left hemisphere of the brain. You perform an experiment in which your subject was presented with an apple only to the left visual field. When asked to identify what he saw, the subject denied seeing anything. However, when asked to point to the correct object, he was able to see and identify the apple. Which reason would explain this deficit?
A) The subject has a brain lesion in the frontal lobes.
B) The subject suffered head trauma to the back of his head.
C) The subject has a tumor in the left parietal lobe.
D) The subject had his corpus callosum severed to control epileptic seizures.

Question

Quizplus · Accepted Answer

The fact that the subject can identify and point to the object with their right hand suggests that the visual information from the left visual field is being processed in the right hemisphere of the brain. Since the subject has had their corpus callosum severed, the two hemispheres of their brain cannot communicate with each other. Therefore, the subject is not consciously aware of seeing the apple in their left visual field because that information is only processed in the disconnected left hemisphere, but the information is transmitted to the right hemisphere which can interpret it and allow the subject to identify and point to the correct object.

Scientists Have Known for Centuries That We "Speak" with the Left