Answer:all the things that you keep the same in the experiment
Explanation:
I think the answer would be needs. Hope this helps.
<span>It is important to study healthy individuals and individuals who have had injury to the cerebral cortex. You can compare healthy individuals (control group) to the people who have had damage to the brain. Studying people with damage to the brain can help us draw conclusions if there are any negative effects on mood or personality.</span>
